# Imperial vs Metric



## billw (19 Aug 2020)

It's dawned on me that some tools I have are metric and some imperial. Now I don't particularly see an issue with it, given that the conversions by 16ths are a maximum of less than 0.5mm out either way and the average is about 0.25mm

Given the only time that these seemingly come into play for accuracy purposes is for chisels and some specialist planes because their blades are imperial, does it actually matter that much or do most people pick one or the other for their tools and stick to it?


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## MikeG. (19 Aug 2020)

It makes no difference. Everything I do is designed in metric measurements, but most of my tools were manufactured when the inch ruled the world.


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## marcros (19 Aug 2020)

I have a bit of a mix too. the only issue that I would warn against is a plan in metric and measuring equipment in imperial. That is asking for issues.


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## Nigel Burden (19 Aug 2020)

I use imperial for most length measurements, but sometimes metric might be easier. Imperial is easier to divide up though. For lighter weights I tend to use metric, but I usually weigh in stones.
So, being of an age where we were taught imperial, I use that more than metric.

Nigel.


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## AES (19 Aug 2020)

Much the same here - mix of both Metric & Imperial tools. The only thing I would say is that on a per-project basis decide which system you'll use and stick to it "religiously". For me that decision is usually based on which system is used on whatever plans/drawings I'm working from.

And I'm not being at all "sniffy", but in most woodwork (all?), and especially for the sort of "woodwork" I do (!!!), any differences that arise from converting Imp to Met and vice-versa are well within the normal allowable tolerances anyway (That's SOMETIMES a different story if we're talking metal working, but for me anyway, most of what I do relies on "fits and feel" anyway, so once we've got to the rough dimension, the actual measurement number is largely irrelevant).


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## MikeG. (19 Aug 2020)

Nigel Burden said:


> ........ Imperial is easier to divide up though.........



Really?

I have a bannister 4'-10 3/8" long and want to space the 12 ballusters out equally. What's my spacing?

Whilst you're doing that, I'll divide 1483 by 13 and then go and make us both a cup of tea. You might be done by the time I'm back.


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## MikeK (19 Aug 2020)

MikeG. said:


> Really?
> 
> I have a bannister 4'-10 3/8" long and want to space the 12 ballusters out equally. What's my spacing?
> 
> Whilst you're doing that, I'll divide 1483 by 13 and then go and make us both a cup of tea. You might be done by the time I'm back.



That's easy, the spacing would be 4 51/104" on center. Now where did I put that tape measure? 

I've been using metric for over 25 years for the ease of calculations and because all of the material and tools readily available to me are metric.

Update: I remembered last night that all of my chisels and plane irons are imperial.


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## Phil Pascoe (19 Aug 2020)

I have no idea what sizes my chisels are - I just use the one that's the right size for what I'm doing.


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## Rorschach (19 Aug 2020)

I have old imperial tools and newer metric tools. I work in both depending on the job. Rough work for breaking down materials I use imperial, bigger units make it easier to mark and divide. Precision work and smaller work is done in metric. Lathe is imperial so I added a DRO to make my life easier.

At the end of the day, use what works for you, as long as it fits it doesn't matter how you measure it.


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## Nigel Burden (19 Aug 2020)

MikeG. said:


> Really?
> 
> I have a bannister 4'-10 3/8" long and want to space the 12 ballusters out equally. What's my spacing?
> 
> Whilst you're doing that, I'll divide 1483 by 13 and then go and make us both a cup of tea. You might be done by the time I'm back.



Ok, I capitulate. 

114.0/1 = somewhere around 5 33/64" or thereabouts.

Now, where's my cup of tea?

Nigel.


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## AndyT (19 Aug 2020)

Well this is all refreshingly pragmatic.

I also understand and use both systems. I learned both at school but lean towards inches for most woodworking, mostly because my tools and old books are in inches. 

Having a mixture is useful for near-miss sizes, such as the choice between a 12mm or a half inch hole, for a tight or loose fit.


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## Distinterior (19 Aug 2020)

MikeK said:


> That's easy, the spacing would be 4 51/104" on center.....



.....I dont even know what those numbers you have written are supposed to signify...?

I was taught to work in both Imperial & Metric scales but I certainly find Metric easier, especially when getting down to really small sizes....What is 51/104ths anyway...?.....Is that a knats bits less than 1/2" on a humid day..?


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## MikeG. (19 Aug 2020)

A couple of weeks ago I watched the guys building Acorn to Arabella dividing up lengths along each frame to get their planking widths individually at each station. They are American, so it was in Imperial. They first converted measurements in inches and eighths to metric inches (ie 10ths), then did the maths, then converted back to 8ths. It took three of them forever. All the comments on Youtube were along the lines of "do it in metric" and "how did you guys ever get to the moon?"


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## MikeG. (19 Aug 2020)

Distinterior said:


> .....I dont even know what those numbers you have written are supposed to signify...?........



Humour. Or irony.


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## MikeG. (19 Aug 2020)

Nigel Burden said:


> .......Now, where's my cup of tea?.........



Over there, on the worktop. Next to the kettle.


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## MusicMan (19 Aug 2020)

I was brought up in Imperial then early metric (cgs) for scientific subjects. I began to use metic exclusively for design when I began as a research student almost 60 years ago and think exclusively in metric (apart from miles). Most of my tools are metric, even the old lathes, miller and bandsaw, since I bought German Boley, Swedish Arboga and Swiss Inca. Only the Wadkin saw is Imperial. Easily overcome for a saw, and anyway I measure using a steel rule to the blade rather than the built-in Imperial rule for width of cut. Considered changing that to metric too, but didn't like to change an original part. A set of Imperial spanners live by that saw and everywhere else is metric. Oh I suppose the old chisels aren't, but I rarely use those where the width is critical (the mortiser is metric). I detest anything other than whole numbers of inches or feet in metric!


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## Distinterior (19 Aug 2020)

MikeG. said:


> Humour. Or irony.



A bit of both Mike..


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## Distinterior (19 Aug 2020)

MikeG. said:


> A couple of weeks ago I watched the guys building Acorn to Arabella dividing up lengths along each frame to get their planking widths individually at each station. They are American, so it was in Imperial. They first converted measurements in inches and eighths to metric inches (ie 10ths), then did the maths, then converted back to 8ths. It took three of them forever. All the comments on Youtube were along the lines of "do it in metric" and "how did you guys ever get to the moon?"



I think I remember something similar being said on the "Tally Ho" project....perhaps that's where you saw it Mike?


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## Just4Fun (19 Aug 2020)

AES said:


> And I'm not being at all "sniffy", but in most woodwork (all?), and especially for the sort of "woodwork" I do (!!!), any differences that arise from converting Imp to Met and vice-versa are well within the normal allowable tolerances anyway (That's SOMETIMES a different story if we're talking metal working ...


A friend designed a car that he eventually put into production as a kit car. When he built the prototype he marked out all the metal for the chassis and was puzzled by an error of about 1mm when he compared the total length of material he had marked out compared to the total required by his design. He spent 3 days tracking down the probem before he would cut a single piece. It turned out to be the cumulative effect of numerous imperial to metric conversions.


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## MikeG. (19 Aug 2020)

Distinterior said:


> I think I remember something similar being said on the "Tally Ho" project....perhaps that's where you saw it Mike?




No, it was definitely A2A. Here, at 23 minutes onwards.


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## Distinterior (19 Aug 2020)

Coincidence then, as Leo from the Tally Ho project was also working out the size of his planking on the last episode I watched.


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## MikeG. (19 Aug 2020)

Yeah, but he knows what he is doing!


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## sunnybob (19 Aug 2020)

60 years using imperial, 12 years using metric because I'm in a metric country. I never use my imperial tape measure now. its easier to use metric. PROVIDED you use ONLY metric.
But I'm still 6 ft 2


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## MikeG. (19 Aug 2020)

It niggles me that metric-only tape measures are the ones you have to go searching for, and that metric/ imperial tapes are everywhere.


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## Daniel2 (19 Aug 2020)

MikeG. said:


> It niggles me that metric-only tape measures are the ones you have to go searching for, and that metric/ imperial tapes are everywhere.



It's the other way around here 
It's only pipe fittings that retain imperial measurement, I believe.


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## Distinterior (19 Aug 2020)

sunnybob said:


> 60 years using imperial, 12 years using metric because I'm in a metric country. I never use my imperial tape measure now. its easier to use metric. PROVIDED you use ONLY metric.
> But I'm still 6 ft 2



.....Surely, you mean 1880mm Bob...?


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## AJB Temple (19 Aug 2020)

Well, woodworkers are a funny lot. I have seem metric users recommend 6 by 2 or 8 by 2 timbers. I have bought 3 metre sawn boards of maple sold as 8 inches wide. I am quite happy with either - it's just mathematics.


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## MikeG. (19 Aug 2020)

AJB Temple said:


> ....... I have seem metric users recommend 6 by 2 or 8 by 2 timbers....



I do that. I'm bi-lingual.


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## Droogs (19 Aug 2020)

MikeG. said:


> Really?
> 
> I have a bannister 4'-10 3/8" long and want to space the 12 ballusters out equally. What's my spacing?
> 
> Whilst you're doing that, I'll divide 1483 by 13 and then go and make us both a cup of tea. You might be done by the time I'm back.




Is that to the centre of each newal post or to the edge Mike, makes a difference


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## Stanleymonkey (19 Aug 2020)

I use metric for most things. Sometimes marking out spacings for some nails or screws is easier because it's a 40 inch length and four inch spacing just leaps out at you and is a no brainer.

The only thing I struggle with here is screws. I got used to the gauges and incremental sizes. 1 inch not long enough? Reach for the one and a quarter. The new metric versions seem to be rounded up/down a bit and confuse me!


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## t8hants (19 Aug 2020)

MikeG. said:


> It niggles me that metric-only tape measures are the ones you have to go searching for, and that metric/ imperial tapes are everywhere.


The metric/imperial tape was invented so you can have the best of both worlds 17" 11mm for example or 5m 9 and half inches.


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## Doug71 (19 Aug 2020)

I swap and change between the two all the time, depends what I am doing. 

As Stanley monkey says screw sizes are a bit of a pain these days, I did prefer it when they were just imperial.


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## MikeG. (19 Aug 2020)

t8hants said:


> The metric/imperial tape was invented so you can have the best of both worlds 17" 11mm for example or 5m 9 and half inches.



 I'm bi-lingual, but even I don't do that.

They don't suit me. I work in mm, and if want to measure and mark from that side of a mixed tape from a set end I have to mark on the wrong side of the tape and transfer the marking out to the other side with a square. I've been working with mixed tapes for 30 or 40 years, and only use one side of them, which is ridiculous. The all-metric tapes I buy suit me far better......which is why I made the point I made. Also, why the hell does a 25 year old, say, want inches on his tape measure?


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## pcb1962 (19 Aug 2020)

Stanleymonkey said:


> The only thing I struggle with here is screws. I got used to the gauges and incremental sizes. 1 inch not long enough? Reach for the one and a quarter. The new metric versions seem to be rounded up/down a bit and confuse me!


This is me. I'm as metric as they come, if you ask me what I weigh it's 107kg, and if you ask me how tall I am it's 1.87 metres. I have metric only tape measures, but when I need a woodscrew it's inch, inch and a quarter, inch and a half, I just cannot see woodscrews in metric. Oddly, if it's a 10mm bolt I have absolutely no problem with it being 10x40 or 10x50, it's just woodscrews.


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## Trevanion (19 Aug 2020)

I'm quite often given measurements for joinery with both systems, quite often on the same piece! Imperial heights and metric widths and vice versa...

Despite being a metric baby I've got a pretty decent understanding of imperial and I really enjoy messing with the other lads sometimes when asked for a measurement to cut at, "Oh, cut it at 10' 2" and 5/16ths" and then followed by a completely blank look and "Err..."


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## MikeG. (19 Aug 2020)

pcb1962 said:


> ....... if you ask me what I weigh it's 107kg, and if you ask me how tall I am it's 1.87 metres.......



 Time to a couple of fasting days a week..


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## large red (19 Aug 2020)

I'm bi lingual school and college all metric but when I started on site all of the carpenters and other trades were Imperial. I did ask them politely t change for me, the forum rules wont allow me to type their replays.
Honestly who would choose Imperial?
Am I correct that in America they use American Standard not imperial??


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## Trevanion (19 Aug 2020)

large red said:


> Am I correct that in America they use American Standard not imperial??



Yes, but the only difference between the two is volume measurements, an imperial gallon is bigger than an american one.


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## Cheshirechappie (19 Aug 2020)

Anybody still use cubits or ells?

(And how many of you Metric enthusiasts go to the pub for a 600ml or two?)


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## Stanleymonkey (19 Aug 2020)

pcb1962 said:


> This is me. I'm as metric as they come, if you ask me what I weigh it's 107kg, and if you ask me how tall I am it's 1.87 metres. I have metric only tape measures, but when I need a woodscrew it's inch, inch and a quarter, inch and a half, I just cannot see woodscrews in metric. Oddly, if it's a 10mm bolt I have absolutely no problem with it being 10x40 or 10x50, it's just woodscrews.



I'd forgotten about bolts - I'm absolutely fine with metric bolts as well.

If you're anything like me - oh dear!!!


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## Phil Pascoe (19 Aug 2020)

Trevanion said:


> Yes, but the only difference between the two is volume measurements, an imperial gallon is bigger than an american one.


Apparently because of evaporation in the casks when they were measured after the transatlantic crossing.


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## Phil Pascoe (19 Aug 2020)

I found an excercise book from about 1964 when I was ten - the sums were in pounds, shillings, pence and farthings (although they went out in 1960), liquid in gills, pints, quarts and gallons, volume in gallons, pecks and bushels and distance in miles, furlongs, chains, rods, yards, feet and inches. No room for decimal point error. I remember being sent to buy potatoes in gallons.


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## TheTiddles (19 Aug 2020)

There is no human alive that ever used “imperial”, the inch has been defined by being a fraction of a metre since the reign of Victoria. So this inch thingy is just like putting a different badge on a car, it doesn’t make it different, but you do it if you like

Aidan


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## Trevanion (19 Aug 2020)

TheTiddles said:


> There is no human alive that ever used “imperial”, the inch has been defined by being a fraction of a metre since the reign of Victoria. So this inch thingy is just like putting a different badge on a car, it doesn’t make it different, but you do it if you like



An inch is still an inch, right?


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## Phil Pascoe (19 Aug 2020)

After 1066, 1 inch was equal to 3 barleycorns, which continued to be its legal definition for several centuries ...

So a millimetre happens to be 0.03937007874 of an inch rather than an inch happening to be 25.4 mm.


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## Cheshirechappie (19 Aug 2020)

TheTiddles said:


> There is no human alive that ever used “imperial”, the inch has been defined by being a fraction of a metre since the reign of Victoria. So this inch thingy is just like putting a different badge on a car, it doesn’t make it different, but you do it if you like
> 
> Aidan


Ah - well - not strictly true, old chap. The inch was defined as being 25.4mm in 1930, not in Victoria's time. Also, the inch goes back way longer than millimetres, first appearing in an English document in the 7th century. It was derived from the Roman 1/12th of a foot, and in the 11th century was defined as the width of three barleycorns (that's 'cos they didn't have a vernier calliper in them days, so had to use something a bit handier as a standard).

Edit to add - Ha! You beat me to it, Phil!

More here - Inch - Wikipedia


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## TheTiddles (19 Aug 2020)

1893 in the USA, and a measurement that’s not repeatable is not a measurement is it, hence the romans were not using inches, they just had a different unit called the same name. 

Wikipedia is also incorrect on some of that page too, the UK was using metric extensively since the early 1800’s

Aidan


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## TheUnicorn (19 Aug 2020)

metric just seems a lot more logical, especially for fine measurements, fractions of inches just get confusing, and confusion leads to error. I do hate it when large measurements are given in mm, like 2400mm boards, not using metres here is a complete nonsense


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## billw (19 Aug 2020)

More annoyingly I’ve just noticed my hammer is imperial, having an 8oz head, but all my panel pins are in mm so now I need a new hammer. Or some older nails.


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## Trainee neophyte (19 Aug 2020)

I live in metric country, so I'm metric. However, Greeks do plumbing in inches, and a one inch pipe is 32mm diameter; half inch is 16mm . I haven't quite worked out why, but I'm working on it. I also know what an inch looks like, (second crease on my thumb), cubits are useful, but I pace in metres, not yards. Ask me how tall I am, and it's 6'3", but I weigh 95kg. Ask me what 6 inches looks like, and I can tell you, but 15cm? Not sure...It's all a bit of a mess


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## TheTiddles (19 Aug 2020)

TheUnicorn said:


> metric just seems a lot more logical, especially for fine measurements, fractions of inches just get confusing, and confusion leads to error. I do hate it when large measurements are given in mm, like 2400mm boards, not using metres here is a complete nonsense



you could use metres, but it would be a 2.400m sheet, so the same number of characters

Aidan


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## Phil Pascoe (19 Aug 2020)

TheTiddles said:


> ... the UK was using metric extensively since the early 1800’s
> Aidan



Extensively? Not in my part of the UK 160 years after that. I didn't come across a single thing in metric until the mid '60s, and that was at school because they were obliged to teach it.
Metres are fine. Millimetres are fine. Centimetres are the work of the devil, invented to confuse us.


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## marcros (19 Aug 2020)

Trainee neophyte said:


> I live in metric country, so I'm metric. However, Greeks do plumbing in inches, and a one inch pipe is 32mm diameter; half inch is 16mm . I haven't quite worked out why, but I'm working on it. I also know what an inch looks like, (second crease on my thumb), cubits are useful, but I pace in metres, not yards. Ask me how tall I am, and it's 6'3", but I weigh 95kg. Ask me what 6 inches looks like, and I can tell you, but 15cm? Not sure...It's all a bit of a mess



inch and half inch internal bore I would expect.

I had only ever known metric until I started working, but now working for an American engineering company I have a familiarity with inches I dont regularly work with measurements. 

Up to a couple of feet I can work in either but I dislike fractional inches. I can picture things in feet up to about 10ft then I struggle. 

From watching YouTube, I can relate better to metal machining where they are working in thou rather than fractions of a mm. 

I have typed this message in 15 pt font, based on 72nds of an inch. imperial is more commonplace than I realised!


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## Phil Pascoe (19 Aug 2020)

TheTiddles said:


> you could use metres, but it would be a 2.400m sheet, so the same number of characters
> 
> Aidan


Either. So long as some clown doesn't decree it's 240cm.


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## TheTiddles (19 Aug 2020)

Phil Pascoe said:


> Extensively? Not in my part of the UK 160 years after that. I didn't come across a single thing in metric until the mid '60s, and that was at school because they were obliged to teach it.
> Metres are fine. Millimetres are fine. Centimetres are the work of the devil, invented to confuse us.


I think you’ve missed the point.
By the 1960’s inches by definition were a number of millimetres. So you were using millimetres, you always have been, you’ve never used anything else, just a conversion of them because, well, because. Before that inches were a fraction of a yard, which was defined as... a fraction of a metre and before that... then inches were a thing, but that was before the 1890’s. Hence no living person has ever used the inch as a measurement standard.

Cm are not SI so I’m with you there. I used to regularly work in inches and metric, usually with amusement as there were still engineers who struggled despite them being the same.

aidan


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## Phil Pascoe (19 Aug 2020)

About 25 years ago I went into the kitchen at work one day at about 10am. Yea!! He's here! What's up? I asked. This was long before the common use of computers (in that sort of environment, at least). How many fluid ounces are there in a litre? 35, I said ( I was a cellarman - I knew all sorts of conversions). Brilliant, we knew you'd be the only person here who knew. They'd seen a recipe in fluid ounces and had no idea what a fluid ounce was.


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## Phil Pascoe (19 Aug 2020)

TheTiddles said:


> I think you’ve missed the point.
> By the 1960’s inches by definition were a number of millimetres. So you were using millimetres, you always have been,
> aidan


And here, millimetres were in common usage a division of an inch. So it's all rather academic. We've all been using barleycorns, ells and fathoms - we just didn't know it.


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## MusicMan (19 Aug 2020)

Just4Fun said:


> A friend designed a car that he eventually put into production as a kit car. When he built the prototype he marked out all the metal for the chassis and was puzzled by an error of about 1mm when he compared the total length of material he had marked out compared to the total required by his design. He spent 3 days tracking down the probem before he would cut a single piece. It turned out to be the cumulative effect of numerous imperial to metric conversions.



Well it should not have been, The inch is defined as 25.4 mm exactly. There is no conversion error. It could of course have been rounding sums at the wrong point.


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## Phil Pascoe (19 Aug 2020)

A late friend, a pharmacist, pointed out that imperial measuremnts served a purpose - there were no decimal point errors in prescribed drug measurements so many fewer accidental overdoses.


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## marcros (19 Aug 2020)

Phil Pascoe said:


> A late friend, a pharmacist, pointed out that imperial measuremnts served a purpose - there were no decimal point errors in prescribed drug measurements so a many fewer accidental overdoses.



I overheard somebody distributing an ounce from their car window when I walked the dog the other night, so this is still commonplace in Leeds!


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## t8hants (19 Aug 2020)

People who insist on measuring in centipedes, should be shot under rule .303". The Imperial system was the finest, most noble and natural system known to man and used until the craven foreigners forced us to change, by the greatest people in the history of the know universe.


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## MusicMan (19 Aug 2020)

Phil Pascoe said:


> A late friend, a pharmacist, pointed out that imperial measuremnts served a purpose - there were no decimal point errors in prescribed drug measurements so a many fewer accidental overdoses.


That seems a good point, but I take loads of meds and the doses are all in integral numbers of milligrams. I don't think I've ever seen a fractional med dose.

My late dad was a pharmacist and I still have his scales. 

Wiki: "The *apothecaries' system*, or *apothecaries' weights and measures*, is a historical system of mass and volume units that were used by physicians and apothecaries for medical recipes and also sometimes by scientists.[1][2][3] The English version of the system is closely related to the English troy system of weights, the pound and grain being exactly the same in both.[4] It divides a pound into 12 ounces, an ounce into 8 drachms, and a drachm into 3 scruples or 60 grains."

Which makes it simple. Written in pig Latin by doctors.


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## MikeG. (20 Aug 2020)

t8hants said:


> People who insist on measuring in centipedes, should be shot under rule .303"........



Harsh, but fair. Millimetres, of course, is what we should all be using.


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## Cheshirechappie (20 Aug 2020)

TheTiddles said:


> 1893 in the USA, and a measurement that’s not repeatable is not a measurement is it, hence the romans were not using inches, they just had a different unit called the same name.
> 
> Wikipedia is also incorrect on some of that page too, the UK was using metric extensively since the early 1800’s
> 
> Aidan


Well, I'd take issue with "extensively" - somebody might have used them for something, but the 19th century was built (literally) in inches, feet, yards, chains, furlongs and miles. It still was far into the 20th century - the plant I worked on as a young engineer had bits dating back to the 1940s, '50s and '60s, the drawings for which were in feet and inches. The seafarers had their own nautical miles, knots and what-have-you. As for "not repeatable", it was repeatable enough for the Romans to build quite a lot of stuff, some of which lasted quite well, so it worked alright for them!


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## Cheshirechappie (20 Aug 2020)

billw said:


> More annoyingly I’ve just noticed my hammer is imperial, having an 8oz head, but all my panel pins are in mm so now I need a new hammer. Or some older nails.


Wait 'till you have to cross-cut a piece of 50 x 25 mm softwood with a 12tpi saw!


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## Yojevol (20 Aug 2020)

I started off in the aircraft industry in the late 60s. I worked on British, American and French designs but I can only remember working in inches. But they were decmalised inches. The commonest sub-unit was the thou', easily measured on our trusty micrometers. Even the Americans used them so I can't understand why all the woody fraternity still use fractions. How on earth do you measure down to a 64th? They only exist on rulers. 
Brian


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## MikeG. (20 Aug 2020)

Yojevol said:


> ........ I can't understand why all the woody fraternity still use fractions....



They don't.


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## billw (20 Aug 2020)

The concept of a decimalised inch just confuses me even more.


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## Dr Al (20 Aug 2020)

MikeG. said:


> A couple of weeks ago I watched the guys building Acorn to Arabella dividing up lengths along each frame to get their planking widths individually at each station. They are American, so it was in Imperial. They first converted measurements in inches and eighths to metric inches (ie 10ths), then did the maths, then converted back to 8ths. It took three of them forever. All the comments on Youtube were along the lines of "do it in metric" and "how did you guys ever get to the moon?"



The answer to that last question is "mostly in metric". All of the guidance systems on the Apollo missions operated in metric units. There was a final conversion stage that put everything into american units for display on the console as it was felt the astronauts would have a more intuitive feel for those units.

I work almost entirely in metric. I've had issues in the past doing stuff based on american engineering drawings where units switch (seemingly) randomly between decimal inches and fractions of an inch and you have to interpret a hole size of 0.109" as meaning you need to get your 7/64" drill bit out. Urgh. I understand the need to go to decimal inches (if the part size isn't a multiple of 1/64"), but switching back and forth just increases the chance of a mistake being made.

I've gradually replaced all my inch/mm mixed tools with metric only so I can use either side of the scale without being forced to switch unit systems.

Of course, being an electronics engineer and having experienced the problem a lot, I reserve the deepest, dankest and most unpleasant place in hell for those who refer to a thousandth of an inch as a "mil".


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## NickM (20 Aug 2020)

MikeG. said:


> No, it was definitely A2A. Here, at 23 minutes onwards.



Mike, you're a very bad man. I had a look at this last night and now I'm completely addicted...


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## Phil Pascoe (20 Aug 2020)

Yes, 32nds and 64ths (for carpentry, certainly) are not really usable. I suspect a better way of using those measurements is/was as my old workmate used to say - cut that 2' 4" full, or 2'4" scant.


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## Phil Pascoe (20 Aug 2020)

Dr Al said:


> ... I reserve the deepest, dankest and most unpleasant place in hell for those who refer to a thousandth of an inch as a "mil".



They can share it with people who use centimetres.


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## MikeG. (20 Aug 2020)

NickM said:


> Mike, you're a very bad man. I had a look at this last night and now I'm completely addicted...



Sorry.


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## Jonzjob (20 Aug 2020)

I remember a mate of mine going into a wood yard and wanting some 10' pine planks. He was told they only sold the wood in metric. When he asked how much it was he was told 10d/foot! That's 10 proper pennies a foot to you youngsters 

When I moved over to France in 2004 it was illegal to buy a lb of potatoes,or anything, and market stall owners were getting fined for doing so. When we did our shopping in France we could go to the market and buy 'une livre' (a pound) of anything we wanted quite legally.

I use both and when measuring anything I tend to look at the measure. If it's awkward in proper measures then I use the metric system. I used to have loads of fun in my local wood yard in Carcassonne telling the guy what I wanted in feet and inches and then showing him my measure. The only purely metric tape I have was given to me one day when I was at the checkout at the Obi Brico, DIY shed on what I found to be Granddad's Day and all of us old pippers were given one. Nice surprise, but no inches 

As far as I'm concerned a metre is only a yard with 10% inflation init  It's also the light wave length of crypton-86 in a vacuum so I'll bet Superman don't like it  Oh yes, last year it was found that it was not an accurate measurement and changed, so if you were using it before then it was not correct. For instance, if you were using it to navigate to the moon you could be several feet out! Don't even think about Mars

Edit : - I forgot to mention that I'm building a 4m scale model gull wing glider at the moment and part of it is skinned with 1/64" birch ply.


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## MikeG. (20 Aug 2020)

TheTiddles said:


> ......By the 1960’s inches by definition were a number of millimetres. So you were using millimetres, you always have been, you’ve never used anything else, just a conversion of them because, well, because. Before that inches were a fraction of a yard, which was defined as... a fraction of a metre and before that... then inches were a thing, but that was before the 1890’s. Hence no living person has ever used the inch as a measurement standard......



As I understand it, the link between a yard and a metre was only defined in 1959. If that is so then you are overstating things somewhat.


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## Dr Al (20 Aug 2020)

MikeG. said:


> As I understand it, the link between a yard and a metre was only defined in 1959. If that is so then you are overstating things somewhat.



It was formally defined in America in 1959 (and in the UK in 1964), but it was used as a standard throughout industry from the early 1930s:



> In 1930, the British Standards Institution adopted an inch of exactly 25.4 mm. The American Standards Association followed suit in 1933. By 1935, industry in 16 countries had adopted the "industrial inch" as it came to be known,[30][31] effectively endorsing Johannson's pragmatic choice of conversion ratio.[27]
> 
> In 1946, the Commonwealth Science Congress recommended a yard of exactly 0.9144 metres for adoption throughout the British Commonwealth. This was adopted by Canada in 1951;[32][33] the United States on 1 July 1959;[34][35][36] Australia in 1961,[37] effective 1 January 1964;[38] and the United Kingdom in 1963,[39] effective on 1 January 1964.[40] The new standards gave an inch of exactly 25.4 mm, 1.7 millionths of an inch longer than the old imperial inch and 2 millionths of an inch shorter than the old US inch.[41][42]


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## Dr Al (20 Aug 2020)

Jonzjob said:


> As far as I'm concerned a metre is only a yard with 10% inflation init  It's also the light wave length of crypton-86 in a vacuum so I'll bet Superman don't like it  Oh yes, last year it was found that it was not an accurate measurement and changed, so if you were using it before then it was not correct. For instance, if you were using it to navigate to the moon you could be several feet out! Don't even think about Mars



"Last year" when it was changed was 1983, so you're about 36 years out there. Also (and I know I'm rising to something that was probably said in jest), the definition was changed to be more consistent over time, not to actually change the distance (and as the inch is defined in terms of the metre, the inch changed at the same time).

It wouldn't affect navigation to the moon or Mars as if the same definition is used for the measurements of where you want to go and where you have been, the actual precise length of that definition doesn't matter (as long as everyone uses the same one, which is where the consistent standard is important).

It's obvious it doesn't affect travel to the moon as it was successfully done in 1969, using metres for the calculations in the guidance computers.


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## large red (20 Aug 2020)

Not been a site carpenter for over 20 years so this may not still be the case but one thing that used to drive me crazy was the fact that ply was only available in imperial 8x4 sheets, therefore if we were building a flat roof we would set out the joists to suit. Plasterboard is metric 1200x2400 so the joists set out for ply are the wrong centres, you either had to add blocking or cut every sheet


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## TheTiddles (20 Aug 2020)

MikeG. said:


> As I understand it, the link between a yard and a metre was only defined in 1959. If that is so then you are overstating things somewhat.



The imperial yard was found to be skrinking around 1895 the standard metre wasn’t, so they started using that instead around 1898 to define what a yard was. So really, unless you know someone who is a few years older than 120...

the fun thing about facts is you can’t overstate them, understate them or anything else, they just are

Aidan


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## Astrobits (20 Aug 2020)

In 1999 NASA lost it's Mars Climate Orbiter because of a mix up in imperial and SI units between NASA and the contractors, Lockheed. Hey-Ho, only 125 million dollars cost!








Mars Climate Orbiter - Wikipedia







en.wikipedia.org




Stick to one system.
Nigel


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## Trainee neophyte (20 Aug 2020)

From Wikipedia, so it must be true:


> The metre is defined as the length of the path travelled by light in a vacuum in 1/299 792 458 of a second. The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's circumference is approximately 40000 km. In 1799, the metre was redefined in terms of a prototype metre bar (the actual bar used was changed in 1889). In 1960, the metre was redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86. The current definition was adopted in 1983 and slightly updated in 2019.



And then I got lost reading about yards...much more fun. I'm supposed to be cutting up bits of wood, but there is always tomorrow.


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## Yojevol (20 Aug 2020)

And what about model railway scales? they're all mm/ft eg:-

Z Gauge. 1.5mm to 1ft, 1:200
N Gauge. 2mm to 1ft, 1:148
TT Gauge. 3mm to 1ft, 1:101.6
HO Gauge. 3.5mm to 1ft, 1:87
00 Gauge. 4mm to 1ft, 1:76
O Gauge. 7mm to 1ft, 1:48
How on earth did that come about?
Brian


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## Droogs (20 Aug 2020)

Astrobits said:


> In 1999 NASA lost it's Mars Climate Orbiter because of a mix up in imperial and SI units between NASA and the contractors, Lockheed. Hey-Ho, only 125 million dollars cost!
> 
> 
> 
> ...


SWMBO has a cousin who works at NASA chemical physicist - proper rocket scientist. She worked on that one lol


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## Dr Al (20 Aug 2020)

Trainee neophyte said:


> From Wikipedia, so it must be true:
> 
> And then I got lost reading about yards...much more fun. I'm supposed to be cutting up bits of wood, but there is always tomorrow.


The 2019 definition didn't really change anything:



> The new definition of the metre is effectively the same as the previous one, the only difference being that the additional rigour in the definition of the second propagated to the metre.
> 
> *Previous definition:* The metre is the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second.
> *2019 definition:* The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299792458 when expressed in the unit m⋅s−1, where the second is defined in terms of the caesium frequency Δ_ν_Cs.


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## Just4Fun (20 Aug 2020)

Yojevol said:


> And what about model railway scales? they're all mm/ft


So what is the weirdest units anyone has worked with?
In my first job they were "going metric" and I had to convert a load of stuff from "gallons per cwt" to "000s litres per tonne". This was called the yield factor and concerned how much cheese was produced from quantities of milk. Yes, in my first job I was a human spreadsheet!


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## Droogs (20 Aug 2020)

@Just4Fun not a cheesemaker then just a clippy prototype 


Just4fun's new avatar


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## MikeG. (20 Aug 2020)

Blessed are the cheesemakers........


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## beech1948 (20 Aug 2020)

Similar to Musicman I was brought up in an Imperial only world. Imperial is better than metric for training ones brain to rapidly calculate the various Imperial measurements. BUT as the world has progressed I have had to force myself to convert to metric and over 15yrs in the 70s/80s I have replaced my machinery with metric equivalents where necessary.

I now run a metric only shop. I even refuse to think in terms of sheets of 8X4 ft but rather of 2400x1200 and try to buy hardwoods in metric only sizes. Oddly there are a few timber yards who have yet to fully convert.

Having done this I now rigidly use metric measurements on all timber. Sold my Imperial only tools.


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## Droogs (20 Aug 2020)

@beech1948, does that include chisels. I would have thought tat a 1/4" chisel would work as well in 18mm wood for a mortise


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## MikeK (20 Aug 2020)

beech1948 said:


> I even refuse to think in terms of sheets of 8X4 ft but rather of 2400x1200 and try to buy hardwoods in metric only sizes.



Full sheets of plywood and MDF here are 2500x1250. Larger sheets are available, but that is the largest I can fit in the bed of my truck. Not including construction timber, hardwood is priced by the cubic meter. Last month, I bought a kiln dried slab of beech (3400x270x52mm or 0.048 cubic meters) at €1,190 per cubic meter.


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## Phil Pascoe (20 Aug 2020)

MikeG. said:


> Blessed are the cheesemakers........


especially the ones at Cheeses of Nazareth?


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## MikeG. (20 Aug 2020)

MikeK said:


> ........ hardwood is priced by the cubic meter.....



It is here, too, although the customer might not see it like that.


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## Racers (20 Aug 2020)

Phil Pascoe said:


> Extensively? Not in my part of the UK 160 years after that. I didn't come across a single thing in metric until the mid '60s, and that was at school because they were obliged to teach it.
> Metres are fine. Millimetres are fine. Centimetres are the work of the devil, invented to confuse us.


Centimeters are used by infants who would be confused by big numbers, most of us grow out of that stage. So if you use centimeters you are still an infant. 

Pete


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## powertools (20 Aug 2020)

For reasons I won't try to explain I work in both.
If anybody else does the same I can highly recommend Advent steel rules, it was another forum member who put me on to them, 1 face is inches only flip it over and the other face is metric only and as a bonus the Veritas ruler stop fits perfectly.
As an aside for thoes of you who work metric only the Advent Visa Versa tape measure is in my opinion the best you can get.


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## lurker (20 Aug 2020)

Ok, so I know exactly how long a mm or inch is and how to convert between them.
So tell me, exactly how long is a gnats?


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## TFrench (20 Aug 2020)

Daughter of a friend was being taught about centimetres at school, put her hand up and said "my dad's an engineer, he says centimetres aren't a real measurement"

I work in a hodgepodge of everything, despite being a metric child. I've only worked with old gits who don't talk metric, or get confused if you do. At work, pretty much everything comes in 1m lengths, but I generally cut it imperial because it only needs to be within 1/4" - its easier to understand in a deafening environment as well when you're calling measurements out to your mate. If it needs to be precise I work in mm, unfortunately the lathe and milling machine are imperial. DRO is definitely on the list for the lathe!


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## MusicMan (21 Aug 2020)

Just4Fun said:


> So what is the weirdest units anyone has worked with?



When I was a research student, we naturally shot the breeze in tea breaks. One friend was an Indian, working on a PhD in electron microscopy, measuring things in Angstroms (that's a tenth of a nanometre in new money) all day. Someone asked him "Das, how deep is the Ganges in your home town?". Without the slightest pause he replied "Oh not very deep, about two elephants".

Pretty practical unit really.


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## Chisteve (21 Aug 2020)

I worked with structural steelwork for 40 odd years and always used millimetres strange the majority of beam/channel section sizes are converted from inches so as example you end up with a 152 x 89 UB or 305 x 165 UB 46 beam and 229 x 76 PFC etc All weighs were in kg/tonnes 

As others have said never used centimetres but do understand 

Im 6 foot 11 and a half and I buy a 4 x 2 timber by the way


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## MikeG. (21 Aug 2020)

Everyone knows this is all just flim-flam. There are only four units of measurement that count: a gnat's nadger, a tennis court, Wales, and a double decker bus.


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## MikeG. (21 Aug 2020)

Chisteve said:


> .........Im 6 foot 11 and a half.......



You missed your calling in life. You'd have made an absolute fortune as a plasterer.


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## Racers (21 Aug 2020)

MikeG. said:


> Everyone knows this is all just flim-flam. There are only four units of measurement that count: a gnat's nadger, a tennis court, Wales, and a double decker bus.


What about an Olympic sized swimming pool and a double decker bus they are favourites of every news channel. 

Pete


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## billw (21 Aug 2020)

Racers said:


> What about an Olympic sized swimming pool and a double decker bus they are favourites of every news channel.
> 
> Pete



Indeed the total amount of gold in the world is often quoted in Olympic swimming pools, because that makes total sense.


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## Dr Al (21 Aug 2020)

billw said:


> Indeed the total amount of gold in the world is often quoted in Olympic swimming pools, because that makes total sense.


Don't you enjoy swimming in molten gold then?


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## Trevanion (21 Aug 2020)

Just4Fun said:


> So what is the weirdest units anyone has worked with?



Hands.

“It’s about two and a half hands”

_“What do you mean it’s two and a half hands!?”_

“I forgot my tape measure, it’s two and a half hands”


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## Phil Pascoe (21 Aug 2020)

Small horse!


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## Just4Fun (21 Aug 2020)

MusicMan said:


> "Oh not very deep, about two elephants".
> 
> Pretty practical unit really.


Certainly interesting but only practical if your animal-training skills are rather better than mine. You could only check the measurement if you could persuade elephants to perform underwater acrobatics. Now that is something I would pay to see

Oddly enough I saw a sculpture yesterday called "animal acrobats" (or that is what it is called if you trust my rather dubious translation from Finnish). It had a giraffe standing on a horse (I think) that was in turn standing on an elephant. Mixing units like that would be worse than mixing imperial and metric. BTW I didn't notice if it was an Indian or African elephant - what inaccuracies would that introduce? This measurement system could lead to more madness than cm.


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## Just4Fun (21 Aug 2020)

Trevanion said:


> Hands.


Something I have never understood: what is the difference between a hand and a span? Is a hand the width of the hand so the fingers are irrelevant?


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## billw (21 Aug 2020)

Just4Fun said:


> Something I have never understood: what is the difference between a hand and a span? Is a hand the width of the hand so the fingers are irrelevant?



Hand - thumb pressed against hand
Span - thumb outstretched


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## TheTiddles (21 Aug 2020)

A hand is 4”, I don’t know when that was decided, but it is therefore also... metric


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## Lazurus (21 Aug 2020)

*Beard-second (distance)*
A unit inspired by the light-year, but for extremely short distances. A beard-second is defined as the length an average physicist’s beard grows in a second (about 5 nanometers).

*Moot (distance)*
One smoot is defined to be equal to five feet and seven inches (1.70 m), the height of Oliver R. Smoot. He was an MIT student whose fraternity pledge in 1958 was to be used to measure the length of the Harvard Bridge. The bridge’s length was measured to be 364.4 smoots plus or minus one ear.
Perhaps it was fate that Oliver Smoot later became Chairman of the American National Standards Institute (ANSI) and President of the International Organization for Standardization (ISO).

*Megalithic yard (distance)*
After analyzing survey data from over 250 stone circles in England and Scotland, Scottish professor of engineering Alexander Thom came to the conclusion that there must have been a common unit of measure which he called a megalithic yard (which was the equivalent of 0.9074 yards, or 0.8297 meters).

*Bloit (distance)*
In the Zork games, the Great Underground Empire had its own measuring system. The most common unit was the bloit, defined as the distance the king’s favorite pet could run in one hour. The length varied greatly, but one account puts the bloit as the equivalent of approximately 2/3 of a mile.

*Pyramid inch (distance)*
Claimed by pyramidologists to have been used in ancient times, a Pyramid inch was one twenty-fifth of a “sacred cubit”, 1.00106 British inches, or 2.5426924 centimeters.


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## AESamuel (22 Aug 2020)

I design in both metric and imperial (even on the same project) because I find they are useful for different things. My tools are all a mixture, and if I am making a joint where I need a specific metric or imperial size, I just pick whichever one fits with the tool I have.


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## Trevanion (23 Aug 2020)

Something occurred to me today I hadn't really thought of and I thought of this thread.

I *always* think in imperial when dealing with the widths and thicknesses (Metric lengths funnily enough) of rough sawn material and leave using metric sizes until it's finish planed to size.

When it's rough sawn I will say it's a 10" x 2" board, because it's roughly that size give or take and 8th

When it's planed I will say it's a 250mm x 50mm board, because it's exactly that size.


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## t8hants (25 Aug 2020)

Sticking with only one system is so inhibiting and restrictive. Its like learning another language, once you have even a smattering your life experience is enhanced, your brain is more flexible in its processes. The problem with the adoption of the metric system in the UK was it was accompanied by a lot of political 'thou shall and shall nots', and 'das ist verboten', imposed by politicians, but insisted upon by civil servants who wanted standardisation in areas the usually had no experience in. The most sensible thing to have done was to teach the basics of both systems and allow each of the industries to sort out amongst themselves what system they wanted to adopt.


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## MikeG. (25 Aug 2020)

t8hants said:


> Sticking with only one system is so inhibiting and restrictive. Its like learning another language, once you have even a smattering your life experience is enhanced, your brain is more flexible in its processes. The problem with the adoption of the metric system in the UK was it was accompanied by a lot of political 'thou shall and shall nots', and 'das ist verboten', imposed by politicians, but insisted upon by civil servants who wanted standardisation in areas the usually had no experience in. The most sensible thing to have done was to teach the basics of both systems and allow each of the industries to sort out amongst themselves what system they wanted to adopt.



So some people would use metric, and some imperial. Some standards would be written in metric, and some in imperial. Some laws would be metric, some imperial. That's a recipe for chaos. Sheer chaos. There is nothing "restrictive or inhibiting" about using metric. Just accept that imperial has gone and move on.


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## Phil Pascoe (25 Aug 2020)

Surely the most sensible thing to have done would have been to have changed currency and all forms of measurement to metric at the same time? It worked for other Countries. Chaos, but chaos once only.


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## pcb1962 (25 Aug 2020)

t8hants said:


> The most sensible thing to have done was to teach the basics of both systems and allow each of the industries to sort out amongst themselves what system they wanted to adopt.


That would have been an utterly stupid idea.


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## Duncan A (25 Aug 2020)

beech1948 said:


> I now run a metric only shop. I even refuse to think in terms of sheets of 8X4 ft but rather of 2400x1200 and try to buy hardwoods in metric only sizes. Oddly there are a few timber yards who have yet to fully convert.


Yebbut standard ply sheets are 1220 x 2440mm. Unless the timber yard is fiddling you!
Duncan


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## Lonsdale73 (25 Aug 2020)

MikeG. said:


> "how did you guys ever get to the moon?"



German - and therefore probably metric - resources


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## Phil Pascoe (25 Aug 2020)

Everyone's probably seen it before, but it's interesting.



> _The US standard railroad gauge (distance between the rails) is 4 feet, 8.5 inches. That's an exceedingly odd number. Why was that gauge used? Because that's the way they built them in England, and English expatriates built the US railroads._





> _Why did the English build them like that? Because the first rail lines were built by the same people who built the pre-railroad tramways, and that's the gauge they used._





> _Why did 'they' use that gauge then? Because the people who built the tramways used the same jigs and tools that they used for building wagons, which used that wheel spacing._





> _Why did the wagons have that particular odd wheel spacing? Well, if they tried to use any other spacing, the wagon wheels would break on some of the old, long distance roads in England, because that's the spacing of the wheel ruts._





> _So who built those old rutted roads? Imperial Rome built the first long distance roads in Europe (and England) for their legions. The roads have been used ever since._





> _And the ruts in the roads? Roman war chariots formed the initial ruts, which everyone else had to match for fear of destroying their wagon wheels. Since the chariots were made for Imperial Rome, they were all alike in the matter of wheel spacing. Therefore the United States standard railroad gauge of 4 feet, 8.5 inches is derived from the original specifications for an Imperial Roman war chariot. Bureaucracies live forever!_



_So the next time you are handed a Specification/Procedure/Process and wonder 'What horse's ass came up with it?' you may be exactly right. Imperial Roman army chariots were made just wide enough to accommodate the rear ends of two war horses (Two horses' asses). 

(I read a version linking it to the width of Nasa's tractors.)_


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## Just4Fun (25 Aug 2020)

Phil Pascoe said:


> Everyone's probably seen it before, but it's interesting.


Not entirely accurate though. Yes, today the USA uses standard gauge railways but originally a lot of their rail system used a 5 ft gauge. They converted about 11 000 miles of track to 4 ft 9 in gauge in 36 hours when they changed to a "standard" gauge.

I only know that because, by chance, I watched a youtube video about it yesterday. Why I watched it is anyone's guess - I have no interest in the subject.


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## billw (25 Aug 2020)

I noticed that Homebase sell boards in 2440x1220 and 1220x607. Where the hell does 607 come from?! Two feet is roughly 610, so that explains the other two numbers, but 607? WHY?!


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## pcb1962 (25 Aug 2020)

billw said:


> I noticed that Homebase sell boards in 2440x1220 and 1220x607. Where the hell does 607 come from?! Two feet is roughly 610, so that explains the other two numbers, but 607? WHY?!


The kerf of that blade that cuts it from the full sheet


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## britinfrance (26 Aug 2020)

I don't understand why there has been a big fuss over the metric system. (Officially the UK has been metric since 1965.) For me, the solution is simple - use metric rules and forget imperial and all the conversion formulae It's exposing you to making mistakes and cock-ups.. The result of using metric rules ignored thinking in imperial, II found that my accuracy improved and the finished result was good. (working to the mm instead of messing with fractions in the imperial system reduces measurement errors.)


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## Cooper (18 Oct 2020)

In 1965, when I was in technical school, we switched to metric, this made science tricky going from BTUs to Watts etc, just before GCEs. But in design and making the switchover was much easier. In 1975 I re-trained as a D&T teacher and in my first lesson observation the teacher in charge asked the 12 year olds to cut inch squares of cloth, to her embarrassment one of the children asked what an inch was. Throughout my career there was a lot of resistance to metric from colleagues who didn't teach maths, science or D&T. Before I retired I was working with disabled children. One day, making xylophones, the classroom support staff found, on the Internet, an American design with the proportions for the notes. They were thrilled as they were in inches, which they said they liked. That was until they had to help the children work out which was bigger 7/16 or 7/32 and they hadn't a clue. I think that summed up one of the reasons why we have such trouble (in this country), we like to live in an imaginary past when everything was easier and better and resist sensible change.


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## clogs (18 Oct 2020)

I use either but was raised with Imperial.....
for a laugh...read on....
I was in big DIY store near Bordox,FR....and was using my Stanley fat boy tape......like u do....
went thru the check out no probs but security pulled me over......a low educated giant of a chap.....
straight off he accused me of stealing it.....now everything getting loud and pushy....with plenty of spectators....
so no problem I asked if he would call the manager over.....
another dumpling in a fancy suit arrives.....
I explained the problem politely and got the usual French shoulder shrug......
When I opened the tape for them to see it was Imperial/metric, these are not available in France.....
So I gave em both barrels......made my day......hahaha.....


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## Peri (18 Oct 2020)

I use imperial for woodwork and metric for metalwork 

I watched a great youtube video that explained that during the Apollo Space Program all the American computers were programmed in metric, but to give the astronauts something they could easily visualize all results were converted back to imperial ! There's a couple of great examples of official NASA documentation that says things like
"The cross-bar is 4.82 metres long, and has 15 3/8's inch holes spaced 32mm between centres" haha


EDIT


Edit2


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## johnnyb (18 Oct 2020)

when making things that were made in imperial its actually dead easy to use imperial. its a dead duck to neglect a thousand years of size specific tools and things. ie window rebates are 1/2 inch. doors are 2ft 6in. the rails and stiles panels are batten, deal and plank etc etc. wardrobes are 2ft deep
but metric is Good for measuring but I design in imperial!


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## johnnyb (18 Oct 2020)

heres why things are made to set(imperial )sizes


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## Ollie78 (18 Oct 2020)

For me Imperial just makes it harder. I always work in mm.
I think it is whatever you were educated with. I would love to be good with imperial, Americans are very fast with fractions as it becomes natural.
My dad was trained as a toolmaker pre metric and his brain works in "thou". 
Of course these are both modern measurements on the grand scheme of things. The Japanese used to use a system where there is no measuring as such just proportions derived from the longest part. With designing things the eye is usually right and tuned in to the golden ratio naturally. That is why all the modern housing developments look strange they are designed to a building regs book and ignore the basic principles of good architecture.
Ollie


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## DBT85 (18 Oct 2020)

I grew up with metric in school and imperial at home so while I'm happy with either, I don't faff around with things when they get to 5 5/16s and all that rubbish. I'll say something is 6ft tall or I need a 2 inch board for example, but if it needs to be actually accurate I'll default to mm. My usual tape measure doesn't even have imperial on it.

But we live in a country where we buy petrol by the litre but talk consumption by the gallon on cars that are made entirely of metric parts on roads marked only in miles where imperial hasn't been taught much in schools for the better part of 40 years.


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## clogs (19 Oct 2020)

and we wont talk about mains wiring colours, either 240 or 440volt....


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## Andy Kev. (19 Oct 2020)

If you've only known metric, I can understand why you might find imperial a bit difficult. IMO there are two aspects to it:

a. Getting a feel for what is e.g. 1", 6" and a foot etc. Then there's the matter of a feel for the commonest fractions: 1/8", 1/4", 3/8", 1/2", and 3/4". That really involves little more than using them. A great help in this would be to buy a two foot, four fold ruler.

b. The maths, at least in so far as it is needed by woodworkers, is actually very easy indeed e.g. half of 3/4 is 3/8 and half of that is 3/16 and so on.
2 x 3/4 is 1 1/2 and so on.

I reckon that if you work in imperial for two projects, you will crack it.

Then there are the things where it doesn't matter in the least bit whether you choose metric or imperial. For instance, yesterday I needed the depth of a groove which I'd cut to the point where it "looked right". I didn't actually need the numbers associated with the depth but rather the actual depth. The nearest thing to hand was a metric combination square, so I measured the depth with it and then transferred that to a wheel gauge without looking at the numbers.

Secondly, if you e.g. want to divide a piece of wood into e.g. 7 equal parts, don't bother with measuring and faffing about with calculations (either metric or imperial). Just use a pair of dividers. No Maths, no headache, job done in seconds.

The big advantage of metric is that it really facilitates complex calculations. You wouldn't want to be without it if you were a physicist or an engineer but how often do you need to do complex calculations in woodwork? The first big advantage of imperial is that it tends to get you thinking in halves, quarters etc. and that is something which is very intuitive and natural and it is there that metric fails badly.

The real trick is IMO to avoid numbers except where you must have them. For instance, I started a project recently where the length was decided by me holding out my arms and saying to myself "about that long" as the top had to fit into a space. "About that long" turned out to be about 37 1/4". I decided that the legs needed to be about an 1/8 of the total length in from the ends. Cue the dividers.

Finally, the really big advantage of imperial is the absolute mass of old tools which are available. And of course there's the matter of N American tools still being in inches. I can imagine somebody ending up with imperial chisels but metric drilling bits. Only rarely do you have to have both e.g. I've got two sets of Allen keys.


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## Cabinetman (19 Oct 2020)

Well thanks Andy Kev, I know how to divide up easily by laying a ruler across at an angle but never used dividers for the same thing and can’t quite picture it, would you care to enlighten me/us please? Ian


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## gridsquat (19 Oct 2020)

This device can be used to divide up equidistant things, but various laws dictate that if you took the trouble to build an up-to-8 steps version your next project would need 9.

I too am old enough to have learnt both units. I can visualise imperial better but I tend to work in whichever side of the tape measure gave me a nice number, if the thing is clearly 12 inches long then I'm not going to call it 304.8mm.


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## DBT85 (19 Oct 2020)

On the subject of using tape measures, despite me now having a metric only tape that is marked both sides on both faces I STILL read numbers upside down because that's how I've done it for years on tapes with both metric and imperial.


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## Cabinetman (19 Oct 2020)

Thanks Gridsquat, yeah I’ve got it now.
Yes I’m the same as you I use whatever is nearest nice round number, but once past the outside dimensions of something I just do everything by proportions, golden square and transferring from one bit to another. Ian


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## Andy Kev. (19 Oct 2020)

Cabinetman said:


> Well thanks Andy Kev, I know how to divide up easily by laying a ruler across at an angle but never used dividers for the same thing and can’t quite picture it, would you care to enlighten me/us please? Ian


Take a piece of wood or a line or anything which represents a straight length. Say you want to divide it into five equal lengths. You guestimate what looks like a fifth of the length and open up the dividers by that amount. You then "step" the points along the line. If you've fallen short, you open up the dividers by a guessed fifth of the amount of the shortfall and close by a guessed fifth in the event of an overshoot. Repeat the foregoing. Once you've made a couple of adjustments, you are usually bang on. Then you can press the points in a bit to mark the wood.

If you're going to have to repeat the division on pieces of the same size, just set the dividers to one side and you'll be ready to do it instantly. The beauty of this technique is that other than deciding by how many times you want to divide the line, you never have to work with numbers.


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## Sheffield Tony (19 Oct 2020)

I use both. If you are making a door, it really is (e.g) 32"x78"x1 3/4. You can use cumbersome metric equivalents if you like, but why ?

And as AndyT said some pages back, it is handy to have some drills in metric and imperial sizes so surely one will give a good fit. Now my auger bit collection has several of the popular sizes, 3/4 and 1/2 - this is useful because I know the shiny plated 1/2" bit is a scant 1/2, the old gedge pattern is a slightly generous 1/2, and that Irwin one is almost a millimetre over.

But if you think that's fun, try working in electronics. Lay out a PCB - half of the components are legacy decimal inch sizes - once 0.1" grid would suit anything. Now newer packages are metric. Some are metric but with decimal inch pin pitches. The CAD package of course supports either a metric or imperial snap grid, and you are forever switching to suit the devices on that bit of board. But better remember which units each feature was drawn in, or get ugly not quite aligned tracks when you edit one while set to metric grid that was drawn with an imperial one. And you think woodwork is hard !


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## Linwoodjoinery (19 Oct 2020)

I work in both. My favourite measurements are still. Good 1/16th or a bare 1/16th!


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## Jelly (19 Oct 2020)

MikeG. said:


> Also, why the hell does a 25 year old, say, want inches on his tape measure?



Despite being born well into the metric era I will often think in imperial to size something up when sketching a rough design: i.e. "_that hand rail should be about 3' 9" from the floor" _but will convert to metric and round non-critical dimensions to the nearest convenient standard size when I actually do the detailed design drawings and prior to working out any fine details.

Pretty much every British young person I meet is similarly at least somewhat conversant in feet and inches, and generally has a natural feel for sizing up human sized objects in imperial dimensions (and mostly sizing up human like weights in stones too).

Add to that, the timber industry also still works in (mostly) standardised metricated versions* of older inch measurements, thus for estimating purposes using feet and inches (which being smaller more imprecise numbers make for easier arithmetic mental maths) are still handy.


* *i.e. W*_hen you ask for a "6 foot length of 2×4" you get "1.8m or 2m length of sawn ex 50×100" and if you ask for "12 feet of 1½×2½ planed and eased", you get "a 3.8m length of 38×68 CLS"... (Of course you have to be wary that Planed and Eased to CLS is sold on dimension, whilst PSE is sold as the "sawn ex" size, so will be 4-6mm under the dimension given, and "sawn ex" is sold with a fairly loose ± tolerance of a few mm either way._


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## cookiemonster (19 Oct 2020)

Just4Fun said:


> So what is the weirdest units anyone has worked with?
> In my first job they were "going metric" and I had to convert a load of stuff from "gallons per cwt" to "000s litres per tonne". This was called the yield factor and concerned how much cheese was produced from quantities of milk. Yes, in my first job I was a human spreadsheet!



For me it has to be Indian lakhs and crores. Try as I did, when in India it still took me ages to work out quantities when those two were in play. 

Also the Swedish mile. But at roughly 10 kilometres that is easier to get your head round.


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## Cabinetman (19 Oct 2020)

So a Swedish mile is two leagues then, don’t get me started on rods and chains.


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## Jelly (19 Oct 2020)

cookiemonster said:


> For me it has to be Indian lakhs and crores. Try as I did, when in India it still took me ages to work out quantities when those two were in play.


10⁵ and 10⁷ respectively right?

I can see that being screwy when western systems effectively indoctrinate us to use steps of 10³.


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## cookiemonster (19 Oct 2020)

Jelly said:


> 10⁵ and 10⁷ respectively right?
> 
> I can see that being screwy when western systems effectively indoctrinate us to use steps of 10³.



It's ok with simple numbers like 1 crore or 2 lakh, or whatever. But when numbers get big and mixed up (or looks mixed up to me), e.g. 1,000 lakh, my head can't cope.


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## Mark Karacsonyi (20 Oct 2020)

frank horton said:


> I use either but was raised with Imperial.....
> for a laugh...read on....
> I was in big DIY store near Bordox,FR....and was using my Stanley fat boy tape......like u do....
> went thru the check out no probs but security pulled me over......a low educated giant of a chap.....
> ...



Had the same here in Budapest, in quite a few stores. On another note, I was helping fit a built in wardrobe in July. All the measurements were off by approx 6mm, the client was not too impressed. After a while we did a measurement comparison. The contractors cheap crappy tape was well off.

He then had the nerve to tell the client, the issues were due to me using a metric/English tape measure. The client didn’t go for it. I picked up the rest of the work.


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## wcndave (20 Oct 2020)

The thing that's nice about Imperial for me, which is a point I see very few, if anyone, pick up on, has nothing to do with the scale whatsoever, but the fact that the divisions are done in fractions. Yes, 12" is nice, can be divided by 2/3/4/6 and 10cm by only 2/5 (to leave whole numbers). But what's really nice is that 1" is divided into fractions, meaning both multiplying, adding, subtracting, and particularly dividing is very easy. So I have 3/4" wood, I want to drill a hole 1/3 the width at the middle, just get a 1/4 drill bit and measure 3/8 from edge.

In metric, I have a 20mm board, have to get a 6.6666mm drill bit. (boards are often 19mm, which is even harder, however as that's a throwback to metric, it's not fair to include it here)

If we had rulers/tools that did fractions, so we had 1/2cm, 1/4cm, 1/8 cm, we could have the exact same convenience of the imperial system.
Of course 1cm is a bit small as the starting point, probably want to start at about.... 2.54cm?

Anyway, my point was that fractions are very very useful, and metric system tends not to use them, and imperial does, hence imperial can feel better/more intuitive.


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## Rich C (20 Oct 2020)

If you had a 21 or 18 mm board though it would be easy in metric. 21mm is a pretty common size for planed timber. You can always find a number that is easy or awkward in either system if you pick it to be such.


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## TheTiddles (20 Oct 2020)

wcndave said:


> The thing that's nice about Imperial for me, which is a point I see very few, if anyone, pick up on, has nothing to do with the scale whatsoever, but the fact that the divisions are done in fractions. Yes, 12" is nice, can be divided by 2/3/4/6 and 10cm by only 2/5 (to leave whole numbers). But what's really nice is that 1" is divided into fractions, meaning both multiplying, adding, subtracting, and particularly dividing is very easy. So I have 3/4" wood, I want to drill a hole 1/3 the width at the middle, just get a 1/4 drill bit and measure 3/8 from edge.
> 
> In metric, I have a 20mm board, have to get a 6.6666mm drill bit. (boards are often 19mm, which is even harder, however as that's a throwback to metric, it's not fair to include it here)
> 
> ...


If only the electronic calculator existed, or a slide rule, or a lookup table, or proportional dividers... in fact if only mental arithmetic existed then the “it’s easy to calculate” response could finally be relegated to history


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## Phil Pascoe (20 Oct 2020)

"It's easy to calculate" often means it's easy to visualise as well.


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## Droogs (20 Oct 2020)

What's mental arithmetic?


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## AES (20 Oct 2020)

Droogs said:


> What's mental arithmetic?



It's where you use your "memory only" to multiply 10 x 10 and come up with the answer 99!


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## Peri (21 Oct 2020)

wcndave said:


> ......... is very easy. So I have 3/4" wood, I want to drill a hole 1/3 the width at the middle, just get a 1/4 drill bit and measure 3/8 from edge.



That's confused me so much I'm not even sure if you're joking or not. 


Really reminded me of that famous Terry Pratchett footnote:

_Two farthings = One Ha'penny. 
Two ha'pennies = One Penny. 
Three pennies = A Thrupenny Bit. 
Two Thrupences = A Sixpence. 
Two Sixpences = One Shilling, or Bob. 
Two Bob = A Florin. 
One Florin and one Sixpence = Half a Crown. 
Four Half Crowns = Ten Bob Note. 
Two Ten Bob Notes = One Pound (or 240 pennies). 
One Pound and One Shilling = One Guinea.

The British resisted decimalized currency for a long time because they thought it was far too complicated."_


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## Dr Al (21 Oct 2020)

wcndave said:


> So I have 3/4" wood, I want to drill a hole 1/3 the width at the middle, just get a 1/4 drill bit and measure 3/8 from edge.



I think I can count on the fingers of one elbow the number of times I've needed to drill a hole of a size that's a proportion of the width of a board. Hole sizes in most of my projects are dictated by what's going into the hole, not how big the board with the hole is. You can always come up with examples that are supposedly easier in one system or another, but there's a reason most of the engineering and scientific world has switched to metric.


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## Phil Pascoe (21 Oct 2020)

I work quite happily in metric, my problem is I can't estimate or visualise in it. I have no idea whether a 90kg 1.85mtr man is heavy or light, short or fairly tall, how far away 15K is, whether 17c is warm or cold, what 300ml of liquid looks like, etc.


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## Brandon Bespoke (21 Oct 2020)

As a company we put everything in Metric but have recently thought we should put Imperial measures on the labels too as, like you say, many people have trouble visualising the amount even if they tend to work in metric.

Brandon Bespoke Oils & Waxes
Tel: (+44) 0125622 0471
Email: [email protected]


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## Rich C (21 Oct 2020)

Dr Al said:


> I think I can count on the fingers of one elbow the number of times I've needed to drill a hole of a size that's a proportion of the width of a board. Hole sizes in most of my projects are dictated by what's going into the hole, not how big the board with the hole is. You can always come up with examples that are supposedly easier in one system or another, but there's a reason most of the engineering and scientific world has switched to metric.


Agreed, also if you want to put a hole in the middle of a board you don't need to measure at all, just set a marking gauge or similar so it reaches the same spot from both sides, easy middle.


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## Andy Kev. (21 Oct 2020)

Phil Pascoe said:


> I work quite happily in metric, my problem is I can't estimate or visualise in it. I have no idea whether a 90kg 1.85mtr man is heavy or light, short or fairly tall, how far away 15K is, whether 17c is warm or cold, what 300ml or liquid looks like, etc.


I'm a 1.83m, 95 kg bloke if thats any help.


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## wcndave (21 Oct 2020)

Peri said:


> That's confused me so much I'm not even sure if you're joking or not.
> 
> Really reminded me of that famous Terry Pratchett footnote:
> 
> _The British resisted decimalized currency for a long time because they thought it was far too complicated."_



I too enjoyed that footnote each time I read whichever discworld book it was.
I was not joking though. 
what is 1/3 of 3/4? 1/4?
what is half of 3/4? 3/8.

Again, the other responses show that the point was missed, and in my opinion, it's a big reason imperial _feels _easy for woodworking.
It uses fractions.

I am all for mental arithmetic, working without measuring etc. However, if you have a pizza and 4 people, you cut across and then across again.
If there's 6, you cut across, then each half into 3. if 8 people.... etc.... 

Where I think it's actually slower with adding, and I've seen some youtubers adding various measurements, thicknesses, then leaving a 1/64 gap here, and 1/16 there, and end up with 29" 17/64 or something.... 

However, often fractions are incredibly quick and easy to use, and they seem to disappear in metric woodworking (and many other disciplines using metric).
You could/can have fractions in metric, they're just not used, so my point was not about imp vs metric per se (of course metric is the standard and makes more sense), but that we lost some of the working with fractions, for some reason...


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## Phil Pascoe (21 Oct 2020)

Andy Kev. said:


> I'm a 1.83m, 95 kg bloke if thats any help.


No.


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## Peri (21 Oct 2020)

It's definitely a mindset. I work with engineering lecturers - some of whom are younger than me - who take the mick out of me because I cant switch from metric to thou's haha


Edit:
We have a variation of the following conversation every year with new students

Student - "I don't do imperial - it's old fashioned and no one uses it"
Lecturer -
How tall are you - they normally answer in feet.
How much do you weigh - majority still answer in stone.
When you go to the pub, what do you order?
What's the miles per gallon on your car?
What's your cars 0-60?

etc etc


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## Droogs (21 Oct 2020)

Andy Kev. said:


> I'm a 1.83m, 95 kg bloke if thats any help.


So a garden fork rather than a rake 


I say this as a 185cm 112kg guy thanks to lots and lots of steriods over the last few months. normally I am 105kg and have been since i was around 17. 6' and 15 1/2 stone 34/36 waist but not now  starvation this winter is warranted me thinks


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## Andy Kev. (21 Oct 2020)

That's about right.

FWIW, I'm with Phil on this: I'm about 1/4" under six foot and probably around 14 Stone (haven't weighed myself for a couple of years).

Even though I'm happy with metric when e.g. reading a book about astronomy (I decided a while ago that it was time to learn something about the universe), I'd still want to know how tall a little green man was in imperial even if I have to convert flubsogs to inches first. And I just give up when I see something in a plan being designated as 770 mm. It's useful to know that a foot is about 30 cm but I reckon that on the whole the woodworker is served better by imperial than metric.


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## Sheffield Tony (21 Oct 2020)

wcndave said:


> Again, the other responses show that the point was missed, and in my opinion, it's a big reason imperial _feels _easy for woodworking.
> It uses fractions.
> 
> I am all for mental arithmetic, working without measuring etc. However, if you have a pizza and 4 people, you cut across and then across again.
> If there's 6, you cut across, then each half into 3. if 8 people.... etc....



And if there are 5, or 7 people ?

I think the point has been made that fractions are convenient if you pick convenient numbers. So 1/3 of 3/4 is easy. 1/3 of 1/2" is also easy, but wait, I don't have 1/6" graduations on my tape. There might just be 1/12" graduations on my rule somewhere, or what ? !/3 of 12mm is easy, and 1/3 of 12.7 is easy - 4.2 (to close woodworking tolerances !) 

This is why I'd argue for using whatever units make sense for the job in hand. Why make a 812.8mm wide door if you can make a 32" one ? Why worry whether it is a metric or imperial drill bit that makes a snug fit for the tenon I turned on a chair part ?


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## Andy Kev. (21 Oct 2020)

Sheffield Tony said:


> And if there are 5, or 7 people ?


That's where dividers come in, although in the case of a Pizza, you'd have to do the old 2 x Pi x R first.

Come to think of it, there's a challenge for a resourceful type: a pair of dividers designed for working out where to make the cuts in Pizzas.

It's beyond me but I bet some geometry wizard could do it.


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## AES (21 Oct 2020)

Sorry, a pizza is NOT a pie, so I don't see where Pi comes into it at all!

(Hat, coat, creeps unnoticed out the door).


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## Andy Kev. (21 Oct 2020)

If I remember aright, no less an authority than the late Dean Martin would beg to differ with you. Did he not sing about the moon being in the sky being "Like a great pizza pie"?

And he was Italian!


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## AES (21 Oct 2020)

Andy Kev. said:


> If I remember aright, no less an authority than the late Dean Martin would beg to differ with you. Did he not sing about the moon being in the sky being "Like a great pizza pie"?
> 
> And he was Italian!



I think it was indeed Dean Martin, but that was not maths, it was purely "poetic licence" (and there was me hoping to creep away unnoticed).


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## Trainee neophyte (21 Oct 2020)

Twelve is a very handy number. Did you know you can count to twelve on one hand by using your thumb to point at the joints of each finger. 3 joints per finger, times four fingers. You can use the other hand to count the number of twelves, and hey presto you can count to 144 without taking your shoes off. I do wonder if this is why twelve was used as much as it was by ancient types - clocks for example, as well as feet and inches.


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## Sgian Dubh (21 Oct 2020)

Trainee neophyte said:


> Twelve is a very handy number. Did you know you can count to twelve on one hand by using your thumb to point at the joints of each finger.


Well, I can on my left hand, but not using my right because the end of two fingers are missing. I guess that makes my left hand useful for old pre-decimal units, and my right hand decimal. I prefer counting using the joints on my right hand, which I suppose means I prefer the decimal or metric system. I've never seen a need to try and use the knuckle count on one hand to convert to the units available on the other hand. Slainte.


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## ArferMo (21 Oct 2020)

I use metric, and haven't looked back since buying a measure with millimetres on the top edge, the bottom edge and the obverse. 19/32nds, et al, now does my head in!

I knew a guy, years ago, who was the secreatry for the UK Douzenal Society. He was a mathematician and produced a magazine for members on the benefits of counting in base 12. The idea has its merits, especially with packing, but the first rule of inovation is "don't upset an established apple cart".


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## TheTiddles (21 Oct 2020)

wcndave said:


> I too enjoyed that footnote each time I read whichever discworld book it was.
> I was not joking though.
> what is 1/3 of 3/4? 1/4?
> what is half of 3/4? 3/8.
> ...



The point is repeatedly missed it seems, what’s half of a metre... it’s 1/2 metre, you can still use fractions in metric, what on earth makes you think that your analogy of the pizza is helpful when you want to divide by 5, or 7? You can also use decimals in imperial, people have been doing that for a couple of centuries. Though as I’ve already pointed out, unless you’re at least 122 years old, your beloved imperial lengths have always been fractions of a metre, so thanks for all using metric your entire lives, we knew you’d get there eventually.

It seems the real question is “what units of a metre do you like using?”, to which anyone with even the most rudimentary of educations would say “any you want, they’re all the same”

Aidan


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## Trainee neophyte (21 Oct 2020)

Sgian Dubh said:


> Well, I can on my left hand, but not using my right because the end of two fingers are missing. I guess that makes my left hand useful for old pre-decimal units, and my right hand decimal. I prefer counting using the joints on my right hand, which I suppose means I prefer the decimal or metric system. I've never seen a need to try and use the knuckle count on one hand to convert to the units available on the other hand. Slainte.


Not everyone has digital digits. It's the sign of a true woodworker.


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## Nigel Burden (21 Oct 2020)

Andy Kev. said:


> I'm a 1.83m, 95 kg bloke if thats any help.



No.

Nigel.


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## DBT85 (21 Oct 2020)

Phil Pascoe said:


> whether 17c is warm or cold


The others I can kind of get, but hasn't the weather been reported in England in C for like 30 years?


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## Nigel Burden (21 Oct 2020)

I'm ok with temperature in C or F, but for most other things I use imperial, except for lighter weights, when I use grams.

Nigel.


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## Sheffield Tony (21 Oct 2020)

Trainee neophyte said:


> Not everyone has digital digits. It's the sign of a true woodworker.


No - they all have digital digits. Just some have decimated them.


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## Phil Pascoe (21 Oct 2020)

DBT85 said:


> The others I can kind of get, but hasn't the weather been reported in England in C for like 30 years?


Yes .............. but I still have to translate it.


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## Dr Al (22 Oct 2020)

Nigel Burden said:


> I'm ok with temperature in C or F, but for most other things I use imperial, except for lighter weights, when I use grams.
> 
> Nigel.



I *can *use inches, pounds and suchlike (although I choose not to in almost all cases), but when someone quotes a temperature in Fahrenheit to me, they might as well be speaking Mandarin for all the sense it makes to me. Similarly the Imperial or American units for thickness of sheet metal or box section thickness. For me it will always be easier to see box section quoted as (e.g.) 25 × 25 × 2 mm (meaning 25 mm square with a 2 mm wall thickness) than 1" × 1" × 14 swg. My calipers don't have an SWG mode...


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## Phil Russell (22 Oct 2020)

I am really enjoying this ... I was raised on imperial but quickly picked metric up at school etc. At work (think agriculture) it was all metric apart for one elderly gentleman who worked in imperial/old English for all measures then back converted when it came to write reports. I still tend to use imperial at home but can happily switch to metric.
But I am surprised no one has mentioned the epitomy of measuring systems, the 'tad'. Quite often when doing some outdoor work where absolute precision is not needed I will use the 'tad' system and its younger brother the 'bit'. So a piece of wood just over 2 ft long could become 24 inches and a bit, or, if a bit longer, 24 and a tad.
Its a lovely world.
Cheers, Phil


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## Lockyear2810 (22 Oct 2020)

The crazy one for me is car tyres. 
Throughout Europe they are still measured using millimetres for the width and inches for the diameter. 
Example. 235/50/18 
So everyone who uses both..... You’re not alone.


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## Phil Pascoe (22 Oct 2020)

Speaking of tads ...


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## Cabinetman (22 Oct 2020)

I got a metal metre rule from wicks a few years ago and on one side it had metric at the top and imperial at the bottom and if you turned it over it was reversed, it was really handy for somebody like me that uses both and which ever is nearest is handy. No they stopped making it. Doh!
Temperature wise I use centigrade for low temperatures as in, its -5 outside and when it’s warm it’s 84 Fahrenheit.


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## Peri (22 Oct 2020)

Cabinetman said:


> I got a metal metre rule from wicks a few years ago ........................



It's only very recently that I saw a carpenters roll up rule that only had metric on it - it surprised me so much I actually made a point of mentioning it to a colleague


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## Cabinetman (22 Oct 2020)

And in America, it’s very easy to buy a roll up rule with only Imperial on it.


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## Felix (22 Oct 2020)

Peri said:


> That's confused me so much I'm not even sure if you're joking or not.
> 
> 
> Really reminded me of that famous Terry Pratchett footnote:
> ...


Then of course you have:

Lady Godiva £5
Cock and hen £10
A score £20
Bag of sand/large £1000


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## Felix (22 Oct 2020)

I think having the ability to work in both is useful particularly if you repair old furniture. 

Also, I think the imperial measuring system is more accurate if a bit more confusing. If you take an inch it's quite easy to measure to the 32nd, but try measuring to the 1/2 mm - that is if you don't go cross-eyed trying to read the scale


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## Peri (22 Oct 2020)

Don't forget ponies and a monkey


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## rogersnowden (22 Oct 2020)

60 minutes in the hour, 60 seconds in the minute! Based on the Babylonian number system which used 60 as its base. Divisible by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30.

Remember tons, cwt, stones, pounds, ounces (and troy ounces and avoirdupois, whatever they were)?

Rods poles perches acres furlongs chains?


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## Sheffield Tony (22 Oct 2020)

bowmaster said:


> I think having the ability to work in both is useful particularly if you repair old furniture.
> 
> Also, I think the imperial measuring system is more accurate if a bit more confusing. If you take an inch it's quite easy to measure to the 32nd, but try measuring to the 1/2 mm - that is if you don't go cross-eyed trying to read the scale



Actually there is one good argument for imperial here. If you have the sort of rule that has some areas in 1/16s, some in 1/20s, some in 1/12s etc, the chances are anything you want to measure will be close enough to an integer number of one or the other of them, but the scales are not so fine you can't read/count them. I can't really read 0.5mm graduations without glasses and good lighting. And as for the rule I have with 1/100" graduations - who can use that confidently ?


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## Arutha (22 Oct 2020)

I heard somewhere about a danish carpenter who gave a gift to an american carpenter. He gave him a rule with danish inches. I remember that it took a while for the american to realize why he got his measurements wrong. The danish inch is 26.15 mm.

Something like this:




__





Folding Rule 82







www.hultafors.com


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## Droogs (22 Oct 2020)

It is interesting that the original numeral system used by human beings (as far as we know) was the Summerian system on which the Babylonians based all their mathematics on and that is base 60. The main reason that is postulated for this is that it allows astronomical observations (based on the Great Year - one complete revolution of our galaxy about it's axis) to be more exact and is the basis of nearly all measuring systems that have ever been used. The exception being Decimal.


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## Yojevol (22 Oct 2020)

Droogs said:


> It is interesting that the original numeral system used by human beings (as far as we know) was the Summerian system on which the Babylonians based all their mathematics on and that is base 60. The main reason that is postulated for this is that it allows astronomical observations (based on the Great Year - one complete revolution of our galaxy about it's axis) to be more exact and is the basis of nearly all measuring systems that have ever been used. The exception being Decimal.


It's a pity that the Man Up There, ie, the Director of Evolution, didn't foresee all the arithmetic we would be getting up to. If He had He would have given us 2 X 6 digits.


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## Droogs (22 Oct 2020)

hey they are all better than binary lol


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## Sheffield Tony (22 Oct 2020)

I'm a computer systems engineer. So I can can count to 1023 on my fingers. What's not to like about binary ?


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## Felix (22 Oct 2020)

Sheffield Tony said:


> I'm a computer systems engineer. So I can can count to 1023 on my fingers. What's not to like about binary ?


It could be 1024 - just depends whether you are using the natural or integer numbering schemes - which you haven't declared (Ex sysadmin) - still running linux <lol>


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## pcb1962 (22 Oct 2020)

Here's a great example of the lunacy of imperial (at 3 minutes in case YouTube doesn't take you straight there)
The guy is a master craftsman, but why on earth would anyone do a calculation like this, instead of
3096 / 16 = 193.5
3667 / 15 = 244.5


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## Felix (22 Oct 2020)

This is interesting in the context of imperial and metric:

It was posted by Peri in the General Chat (Off-Topic) forum

The book is copyright free and you can download it from:

www.filefactory.com/file/4ff2amdb1f5y/n/J._P._Law_-_The_Beginners_Guide_to_Fitting_1935.pdf

If you will examine a rule you will see that it is easy to
measure inches and fractions, such as l ½ in., 2 1\- in., or 3 in.
Sometimes, however, it is necessary to measure in decimal
dimensions, auch as 1.620 in. This generally throws a beginner
into confusion which a little more knowledge will dispel.
Since rule measurement can only be approximate, we use
the nearest dimensions on the rule to the size we require.
One point six twenty (1.620) = one inch, six-tenths of an
inch, and two hundredths of an inch.
Now 2/100 = 1/50 and as 1/50 divisions are marked on
the rule, we may measure as in Fig. 11.
Similarly, it should be remembered that one-twentieth of
an inc.h = .050 in., or fifty thousandths of an inch. Thus,
if a measurement of 4.350 in. is required, this also may be
directly measured.
The decimal equivalent of fractional sizes 1/64 in., 1/32 in.,
3/64 in., up to 1 in. should be memorised by the student. A
mastery of these conversions will well repay the little trouble
required.


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## Andy Kev. (23 Oct 2020)

Droogs said:


> It is interesting that the original numeral system used by human beings (as far as we know) was the Summerian system on which the Babylonians based all their mathematics on and that is base 60. The main reason that is postulated for this is that it allows astronomical observations (based on the Great Year - one complete revolution of our galaxy about it's axis) to be more exact and is the basis of nearly all measuring systems that have ever been used. The exception being Decimal.


I've been desperately trying to resist this but I just can't.

You do realise that you're implying that the Babylonians had not only a grasp of the existence of the Milky Way but also the fact that it rotates about its centre and that that idea is bread and butter to the people who are convinced that such knowledge shows that we were (possibly still are) visited by aliens?

It's enough to make you set up your workbench in a crop circle.

Anyway, I'm not sure that I'd want to have intergalactic contact with somebody who doesn't get inches.


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## Droogs (23 Oct 2020)

@Andy Kev. 
I am totally agnostic with regard to whether there are human or non human beings that reside on some other ball of dirt whizzing about the multiverse and if they have been here or not. I see no definitive proof either way, so I do not know.

Having had a total obsession about the Sumerians (since I played the "Royal game of Ur" and Indianna Jones as a child), Akkadians and the growth of civilizations in the fertile crescent to the point that my entire secondary school subject choices were focused on being able to get to UofC and their archeology program (I just missed out on a scholarship) and unfortunately my parents could not afford to pay, so I ended up taking the shilling instead. I also had a childhood in which biblical history was rammed into my head. This only increased my desire to learn about the ancient world. I soon managed to divest myself of the superstitions but never the interest in the cradle of civilization or ti's developement.

There are a growing number of respected and acknowledged experts in various fields of academic study who are not interested in little green men at all but are postulating that in certain areas previous societies had a level of knowledge about Astronomy and Mathematics at least on a par ours as of the 1800s. Maths doesn't lie and when you look at the numbers surrounding many of the ancient worlds relics they show an amazing level of sophistication in those areas. 

It is unfortunate that so many people do not believe that *we *human beings are capable of such thinking so long ago. More and more evidence is being found and explained from further in our past thatn ever before thanks to technology and our own growing knowledge, that shows the possibility that our ancestors weren't the troglodites they are portrayed to be. Known *recorded *history is only 6k to 8k years old and yet we have physical evidence of astronomically based super structures all around the world that are provably older than those records. 

The people of the world in those ancient times did not think the world was a pizza on the back of a big turtle, they were perfectly aware it is a globe and of its position in the solar system and they dynamics of it's relation with the other "heavenly" bodies. 
Man in his current physical state of being has had the same brain structure and reasoning pattern for over 200 000 years by the latest level of our knowledge. Do you seriously think that they were all running around with an IQ at the level of a moron no there will have been some pretty smart cookies around who would have worked things out. We know that civilization tends to grow around coastal regions We are becoming more aware that over the last 12 - 15K years we have lost a coastline equal to China in size due to global events. We *know *that sea levels rose over 400 feet in a geologically minute time period of a couple of centuries around 12k years ago for definite fact, they are just arguing over the cause. That surely must have have a major devastating impact on our ability to pass on our sum total of human ken to the next generations and sunk proof of our passing below a level we could easily reach until today.

Nothing to do with aliens or crop circles or any other such bovine poo. Just the acknowledgement that our predeccessors were probably a hell of a lot smarter than we in our arrogance give them credit for.


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## Phil Pascoe (23 Oct 2020)

Droogs said:


> The people of the world in those ancient times did not think the world was a pizza on the back of a big turtle, they were perfectly aware it is a globe and of its position in the solar system and they dynamics of it's relation with the other "heavenly" bodies.



I seem to remember someone in more recent history getting himself in the doggie doodah for suggestion the earth orbited the sun.


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## bjm (23 Oct 2020)

Phil Pascoe said:


> I seem to remember someone in more recent history getting himself in the doggie doodah for suggestion the earth orbited the sun.


I seem to recall the late Stephen J Gould covered this in one of his many essays - I no longer have his books - and I'm pretty sure it was only in the west that the earth-centric view held because of religious dogma? Same for the flat earth theory which, I seem to recall, only originated around the 17th century?? Any SJG readers out there?


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## Droogs (23 Oct 2020)

While at the same time all of Asia Minor and the Far East knew of and taught the solar system was helio-centric and that the Earth was a globe. Infact the shape of the Earth was never an issue as even the "church" accepted that.

We Europeans are rather arrogant, in that, because we had the Renaissance and then leap frogged the knowledge level of other civilizations 300 years ago the masses here think everyone else was rather thick and backward.


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## Andy Kev. (23 Oct 2020)

Droogs said:


> @Andy Kev.
> I am totally agnostic with regard to whether there are human or non human beings that reside on some other ball of dirt whizzing about the multiverse and if they have been here or not. I see no definitive proof either way, so I do not know.
> 
> Having had a total obsession about the Sumerians (since I played the "Royal game of Ur" and Indianna Jones as a child), Akkadians and the growth of civilizations in the fertile crescent to the point that my entire secondary school subject choices were focused on being able to get to UofC and their archeology program (I just missed out on a scholarship) and unfortunately my parents could not afford to pay, so I ended up taking the shilling instead. I also had a childhood in which biblical history was rammed into my head. This only increased my desire to learn about the ancient world. I soon managed to divest myself of the superstitions but never the interest in the cradle of civilization or ti's developement.
> ...


I was only being lighthearted ... honest!

Actually, I'd heard about the sea level rise thing and about sunken cities off the coast of India which would, of course, have once been coastal cities.

I don't have any difficulty in accepting that ancient civilisations could have been hot on the astronomical front. Theoretically if you can accept that 1 +1 = 2, you should by dint of much effort and loads of genius be able to work your way up to E = m x c squared (can't work out how to write formulas on this forum), simply because maths seems to be so chillingly absolute and of course pure maths is independent of physical observations and only dependant on a writing implement and something to write on.

The problem is, as you point out, of our time. The gap in _our_ knowledge about ancient times has the alien theorists rushing in to fill the gaps. Their reasoning seems to be along the lines of, "I can't imagine them being that advanced, so they must have had alien help". A falser case of logic you couldn't imagine. The only thing that I know of that even remotely works in the favour of these people is an African tribe which allegedly has knowledge of a star that you can't see with the naked eyed.

FWIW I'm convinced that there are many inhabited planets out there and statistically it is highly likely that at least one of them works in inches and plays rugby.


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## Droogs (23 Oct 2020)

let's hope so


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## Andy Kev. (23 Oct 2020)

Droogs said:


> let's hope so


Are you sure you hope so?

Can you imagine the 6 Nations plus 1 planet tournament when it turns out that all the Blxxrgaglians are at least 7' 3" and weigh 22 stone?


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## Droogs (23 Oct 2020)

that only gives them a 6" height advantage my lot has them beat everywhere else


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## Andy Kev. (23 Oct 2020)




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## Felix (23 Oct 2020)

Andy Kev. said:


> Anyway, I'm not sure that I'd want to have intergalactic contact with somebody who doesn't get inches.


But they might come in handy if you've got a big lump of timber to move around the workshop.....


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## raffo (25 Oct 2020)

The Mayas and their predecessors invented a mathematical system in base 20. They also invented the concept of zero and developed a pretty sophisticated mathematical system. They also had a pretty advanced astronomical knowledge. On top of that they also developed a writing system. Unfortunately, religious zeal compelled the Spaniard priests to burn every Mayan written document they got their hands on.

In Peru, the Nasca civilization left very large symbols and geometrical figures in the desert. The archaeologists studying them claim they represent constellations or some astronomical representation. Unfortunately, the inhabitants of that part of South America didn't develop a writing system and their knowledge has been lost.

Regarding the Babylonians, isn't it amazing that we're still using a system developed to track time that is probably 4 or 5 thousand years old.

Another thing to wonder, just about 100 years ago the common consensus was that our Milky Way was the all there was, that was the universe. The discovery of galaxies and the size of the universe is amazing if one thinks about. I even remember mentions of the "Andromeda nebula" in the 70s, old names are hard to change.


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## Andy Kev. (25 Oct 2020)

If you look at any of the pictures of spiral galaxies, like the Andromeda, just hanging there in space and if you even try to envisage the sizes involved, it is quite mind boggling.

And they measure them in light years which is cheerfully non-metric.


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## Felix (25 Oct 2020)

Andy Kev. said:


> If you look at any of the pictures of spiral galaxies, like the Andromeda, just hanging there in space and if you even try to envisage the sizes involved, it is quite mind boggling.
> 
> And they measure them in light years which is cheerfully non-metric.


Isn't the speed of light something like 3 x 10**8 metres per second multiply that by 3.157 x 10**7 (number of seconds in a year) the answer to which looks like a metric number <lol>


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## Andy Kev. (26 Oct 2020)

bowmaster said:


> Isn't the speed of light something like 3 x 10**8 metres per second multiply that by 3.157 x 10**7 (number of seconds in a year) the answer to which looks like a metric number <lol>


Ah but … the speed of light is an absolute, a bit like a piece of wood: the units in which you choose to measure it- let us compromise on a piece of wood flying through the workshop at less than the speed of light due to frustration at mangling some dovetails - are entirely arbitrary i.e. anything but absolute.

Gotcha! ( er … I think.)

Come to think of it, the number of seconds in a year isn't very metric either.


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## Dr Al (26 Oct 2020)

Andy Kev. said:


> Ah but … the speed of light is an absolute, a bit like a piece of wood: the units in which you choose to measure it- let us compromise on a piece of wood flying through the workshop at less than the speed of light due to frustration at mangling some dovetails - are entirely arbitrary i.e. anything but absolute.
> 
> Gotcha! ( er … I think.)
> 
> Come to think of it, the number of seconds in a year isn't very metric either.



The second is metric† though. The number of metres in the length of my workshop isn't what I think you're calling "very metric", but the metre is.

† In the sense that it's one of the SI units


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## Andy Kev. (26 Oct 2020)

Dr Al said:


> The second is metric† though. The number of metres in the length of my workshop isn't what I think you're calling "very metric", but the metre is.
> 
> † In the sense that it's one of the SI units


I'm glad you got that little footnote in. It's a get out clause worthy of a politician! And I do admire the sheer audacity of it.

The following is to be taken with caution as it is a long time since I did any physics at school: units of time are anything but metric as their start point is the number of days which the earth takes to go around the sun (365 and a bit). That is very unmetrically divided into 12 months, each with differing numbers of days. However, a day is always 24 hrs (although doesn't it change every few thousand years due to speeding up or slowing down of the earth's rotation?) and then we chop that down to the second in the fashion with which we are all familiar.

Thereafter the scientists _treat _the second metrically , milli-, micro, nano- etc etc. for the simple reason that doing their sums would lead to a lot of headaches if they didn't.

The metre itself is by definition metric. It is also by definition arbitrary. Didn't they kick it off by saying, "Right we've got this bar of platinum in a shed in Paris and we're saying that it is a metre long i.e. it's the reference standard for the metre". There is of course nothing intrinsically significant to that length of bar, hence its arbitrariness. And if I remember rightly, no matter how much you try to control the temperature at which it is stored, it is likely to expand or contract by a micromilliwobble every now and then. Didn't they then adopt a different definition based on a true absolute constant, probably measured according to something or other in a vacuum?

Imperial is also of course arbitrary: "How long's the King's foot?" "Er … that long." "Right, as of now, that's a foot."

The beauty of imperial is that it then uses divisions and multiples of feet in _human_ terms e.g. a furlong is a furrow long (if memory serves that's the length of a ploughed furrow and it comes in at 220 yards). What this adds up to is that imperial has a very pleasant, villagey feel about it whereas metric is perfect for the cold, unimaginable distances of the cosmos and the equally unimaginable tiny spaces within atoms. It's sort of the difference between enjoying a pint while watching a cricket match on the green versus downing a mineral water while discussing this year's accounts.

Mine's a Guinness.


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## J-G (26 Oct 2020)

Andy Kev. said:


> Didn't they kick it off by saying, "Right we've got this bar of platinum in a shed in Paris and we're saying that it is a metre long i.e. it's the reference standard for the metre".


NO.

Quite the opposite. The original definition of a Metre was 1 10millionth of the distance from the Equator to the North Pole along a Great Circle. The conversion to a Platinum Rod came later simply for the convenience. It is now defined in terms of the speed of light which is an absolute constant not subject to variation due to temperature or anything else.

You also have the definition of Time the wrong way round. The SECOND is the basic SI unit of time which is now defined in terms of the frequency of vibration of a Caesium-133 atom.


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## Dr Al (26 Oct 2020)

Andy Kev. said:


> ...
> 
> units of time are anything but metric as their start point is the number of days which the earth takes to go around the sun (365 and a bit). That is very unmetrically divided into 12 months, each with differing numbers of days.
> 
> ...



You seem to be picking on one part of the meaning of the word "metrically" - the use of "metric prefixes" like nano. You can use metric prefixes with any system (look at the thou for an example - effectively one milli-inch). That is only one part of the metric system; another very important one being the concept of Coherence, which to my understanding basically means that you _very rarely _need arbitrary constants when performing calculations. For example, a watt is *one* joule per second whereas a horsepower is *550* foot-pounds per second.

The second as a unit is metric in the sense that it is a fundamental part of the metric system of units known as SI and is coherent with the other metric units. It is now defined in terms of things that don't change anywhere in the universe, as are all elements of the metric system (and other elements like the inch that are defined in terms of the metric system).

All units are arbitrary in that you have to pick a number to start with. The fact that the metre was initially picked as a (not very accurately measured) part of the earth's circumference, the second was picked as part of a day and the foot was picked as the length of someone's foot is irrelevant. The derived units are arguably more important as things like the watt are simple whereas things like horsepower need conversion factors.

Imperial units might well be better for measuring furrows but for most things that any of us are going to use in a workshop, there's no fundamental difference in what the two systems are capable of. The inch and the millimetre are based on the same standard (the metre) after all. Whether you prefer working to millimetres or 1/32", or prefer microns or ten-thousandths of an inch is arguably personal preference, although having multiple systems of units in the world (and even just in this country) makes things more difficult for everyone.

The metric system is objectively better for scientific use and having two systems undoubtedly increases confusion, as does the imperial system's habit of switching between fractions and decimals arbitrarily - I've seen mechanical drawings with instructions like 'drill with a #6 drill, then bore to 0.240", then ream 1/4" '. I for one would much rather see 'drill with a 5.2 mm drill bit, then bore to 5.8 mm, then ream 6 mm". Similar comments can be made about material thicknesses in AWG or SWG. I would be much more in favour of inches if they were used consistently.

One thing I will say in favour of imperial stuff is that quite a few of the imperial conventional sizes (with lots of exceptions of course) are slightly bigger than the metric equivalents. That means if I buy a bit of 1" stock and stick it in the lathe, I can turn it down to 25 mm and guarantee concentricity with diameters. If I'd bought 25 mm stock, that wouldn't be possible!

I also think there's a special place in hell reserved for people who quote temperatures only in Fahrenheit...



Andy Kev. said:


> Mine's a Guinness.



I'll have 50 ml of Springbank.


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## Droogs (26 Oct 2020)

Your all wrong. You are confusing and conflating Decimal and Duodecimal numbering systems. 1m is metric no matter what number base is used to name or compare it. I think the problem first occured during the 70's for most brits as both metrification and decimalisation were happening at the same time

@J-G I think you will find that constant is relative, especially once over the event horizon of a black hole


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## AES (26 Oct 2020)

Erm ................. what about the nautical mile and the (attached) knot - nautical miles/hour - then?

Mind you, I'm just a simpleton, so the idea of a horse raising a pound of something over a foot seems nice and simple to me - but no idea if the original horse was "calibrated" or not (or even if he was measured before or after the poor creature had just had his oats + a sugar lump)! 

But as said, I'm just a simpleton, so you can keep all your beery and watery stuff thanks - mine's just a goodly-size (Imperial or Metric, I don't care) of Malbec.


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## AJB Temple (26 Oct 2020)

Please can someone now tell me something useful to put my mind at rest. I would like to get my head around what was there before the (assumed) Big Bang. Also how can I imagine infinitesimal space? I feel this is sucking me in.


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## Andy Kev. (26 Oct 2020)

You learn something every day.

@ J-G I'd not heard the equator to N Pole thing before and that is of course also necessarily arbitrary. Agreed about basing the metre on the absolute constant of the speed of light (in a vacuum?) but am I not right in thinking that it still does no more than precisely define in absolute terms the the length of the arbitrary metre. We could just as easily determine the foot in terms of the speed of light but it would be no less arbitrary. I'm not suggesting that arbitrary is in any way inferior but the more I think about it, the more arbitrary units of measurement seem to be unless the unit of measurement is itself an absolute e.g. the mass of a proton.

@Dr Al I agree with all of that. I do however, have the impression that metric is presented as being somehow superior. It can't be of Course, as we agree that all units of measurement are arbitrary. What it undoubtedly is, is mathematically more convenient, especially for physicists, engineers etc. The woodworker has a choice of which system he finds to be more convenient. I tend to prefer imperial for woodwork because it seems natural to consider halves, quarters, eighths of units (in this case the inch) for practical purposes. Obviously other people prefer metric. I was brought up with both systems and have come to prefer imperial for the real world and metric for when e.g. I'm trying to understand astronomy or nuclear physics. 

Isn't the real problem time? (Genuine question.) We're not quite sure what it is and it is - almost incredibly - relative due to the famous speeding up/slowing down aspects of it for high speed space travellers.

@Droogs I refuse to offer an opinion on black holes until I've heard Paul Sellers on the topic. Also Einstein was not known for his mortices and tenons which does of course cause the thinking man to raise an eyebrow.


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## Cheshirechappie (26 Oct 2020)

Hmm.

Seems that metric is 'scientific', and imperial is 'human'.

It's a bit easier doing engineering calculations in metric units (speaking from long and sometimes bitter experience), so they have their place. But so do imperial units, including time. When the day can be divided as so many fractions of the time between one sunrise and the next, it's easier to get a handle on than multiples of the numbers of oscillations of a certain atom in a vaccuum, and distances being measured in the length of your foot, or multiples or divisions thereof, is likewise more readily comprehendable than the fractions of the distance between the Earth's pole and it's equator.

Thus, they both have their place. Personally, if I'm ever again called upon to undertake the calculations necessary to prove that a chemical plant piping system will survive an earthquake of a given magnitude, I'd prefer to do said calcs in metric and base 10. But I'd still prefer to work wood in feet, inches and tads, and finish the day somewhere around sunset, perhaps with with a contemplative pint.


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## Andy Kev. (26 Oct 2020)

AJB Temple said:


> Please can someone now tell me something useful to put my mind at rest. I would like to get my head around what was there before the (assumed) Big Bang. Also how can I imagine infinitesimal space? I feel this is sucking me in.


Try this:






An Introduction to Galaxies and Cosmology: Amazon.co.uk: Jones, Mark H., Lambourne, Robert J. A., Serjeant, Stephen: 9781107492615: Books


Buy An Introduction to Galaxies and Cosmology 2nd Revised ed. by Jones, Mark H., Lambourne, Robert J. A., Serjeant, Stephen (ISBN: 9781107492615) from Amazon's Book Store. Everyday low prices and free delivery on eligible orders.



www.amazon.co.uk





Cracking book although the equations should perhaps have a parental advice warning.

The problem is that before the big bang it would appear that all time and space was in the same dot, then time began. But there must have been something outside the dot … another dot i.e. another universe? This is what keeps clever people awake at night.


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## Phil Pascoe (26 Oct 2020)

AES said:


> But as said, I'm just a simpleton, so you can keep all your beery and watery stuff thanks - mine's just a goodly-size (Imperial or Metric, I don't care) of Malbec.


Another bit of weirdness when we went metric - why wasn't a bottle of spirits left at 75cl - very nearly the same as it measured before, 26 fl.oz? It's an unnecessary problem if you're a licensed trade buyer as you have to work out the prices per cc of both bottles and litres (or 1 1/2ltrs). So much simpler if you could look and think instantly ah, the bottle's ten quid, the litre's £12.50 so it's cheaper, or the litre's £13.75 so it's more expensive.


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## TheTiddles (26 Oct 2020)

Andy Kev. said:


> The beauty of imperial is that it then uses divisions and multiples of feet in _human_ terms e.g. a furlong is a furrow long (if memory serves that's the length of a ploughed furrow and it comes in at 220 yards). What this adds up to is that imperial has a very pleasant, villagey feel about it whereas metric is perfect for the cold, unimaginable distances of the cosmos and the equally unimaginable tiny spaces within atoms. It's sort of the difference between enjoying a pint while watching a cricket match on the green versus downing a mineral water while discussing this year's accounts.
> 
> Mine's a Guinness.



except it isnt, and hasn't been for over a century, as even before then, people knew that having something that variable was a bad plan in the new modern world of the early-19th century, it took another 75 years (and a big fire) to totally do away with it, as you‘ve said, it’s just at a way of dividing up a known standard as agreed upon by everyone. You could measure everything in otter‘s tails if you so desired, you might not find them on tape measures but thankfully they are exactly 34mm wide, at which point, you may as well skip a stage and just use the mm straight.

Aidan


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## Droogs (26 Oct 2020)

@AJB Temple To put your mind at rest, Before the Big Bang there was just Birmingham


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## AJB Temple (26 Oct 2020)

Andy Kev. said:


> Try this:
> 
> 
> 
> ...



I find the more I study the less I understand. Back in the day I studied maths at PhD level and spent (ie wasted) a lot of energy theorising about infinity. There are numerous learned theories about the dot. The one I like best contrives that there is a huge expansion, followed by a huge contraction into a dot again (takes a while). There could be an infinite number of dots doing this - not necessarily at the same time (using "time" in its wider sense). But it still leaves me with "how did the dots get there?" and "are the dots contained by anything?"


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## Andy Kev. (26 Oct 2020)

AJB Temple said:


> I find the more I study the less I understand. Back in the day I studied maths at PhD level and spent (ie wasted) a lot of energy theorising about infinity. There are numerous learned theories about the dot. The one I like best contrives that there is a huge expansion, followed by a huge contraction into a dot again (takes a while). There could be an infinite number of dots doing this - not necessarily at the same time (using "time" in its wider sense). But it still leaves me with "how did the dots get there?" and "are the dots contained by anything?"


It seems to me that we have a choice of options to believe in. The problem with one of them is that being physical creatures in this universe, it is almost impossible for us to imagine and that is the Single Dot Hypothesis. How can we cope with the notion of all time and space being contained in one infinitely small dot? I think it very difficult because, being of this universe, while we can accept the existence of a dot, we instinctively say, "But there must be something outside the dot" and as far as I can see the SDH demands that there be nothing outside.

Therefore I tend to the Multiple / Infinite Dot Hypothesis but on the basis of nothing more than as a creature of this universe, I am not equipped to conceptualise anything else.

As a kid I came to the conclusion that infinity isn't worth bothering about because it is scuppered every time by two words: Plus One. I can accept that some things are infinite, time being the obvious candidate and space possibly running it a close second. However, as a definable working concept it's a bit of a non-starter.


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## J-G (26 Oct 2020)

Whilst we are discussing 'Imperial' as opposed to 'Metric' we are also limiting our discussion to the 'British Imperial' measures. On a wider front has anyone an opinion on the Russian Imperial system and whether that is more useful for some tasks than the Metric system?

In weight - 1 Rad is 14 Pud and a Korob is 7 Pud but a Berkovets is 10 Pud. 1 Pud is 40 Funt and a Funt is 96 Zolotniks whilst a Lot is 3 Zolotniks.

In Length - 1 Verst is 500 Sazhen, a Sazhen = 3 Arshen and an Arshen is 16 Vershok. There were 4 Chetverts to the Arshen but the Chetvert as also a liquid measure being a ¼ of a Bochka or 10 Vedro.

No wonder they came to their senses in 1917 when they changed to the Metric syatem !

I feel a quiz round coming on


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## J-G (26 Oct 2020)

Andy Kev. said:


> As a kid I came to the conclusion that infinity isn't worth bothering about because it is scuppered every time by two words: Plus One.


I remember very clearly that Infinity cost me a relationship  

Trying to explain the concept to someone who couldn't divide by 10 !!! Yes, she couldn't use metric, the idea of cutting a round cake into 10 portions was beyond her comprehension.


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## bjm (26 Oct 2020)

AJB Temple said:


> Please can someone now tell me something useful to put my mind at rest. I would like to get my head around what was there before the (assumed) Big Bang. Also how can I imagine infinitesimal space? I feel this is sucking me in.


I was listening to a scientist recently who said that when explaining theories, such as Quantum Mechanics, there comes a point where words fail to make sense and only the maths becomes plausible. The only problem with that explanation is that very few people, including mathematicians, can claim to grasp these constructs. Accept it/deny it - that's your choice?


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## AES (26 Oct 2020)

@J-G: " ........... the idea of cutting a round cake into 10 portions was beyond her comprehension."

I can't see why that would be a problem if there was only the two of you  

(Yup, I'm determined to keep this thread right down at the - low - level that I maybe understand)


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## Felix (26 Oct 2020)

Dr Al said:


> You seem to be picking on one part of the meaning of the word "metrically" - the use of "metric prefixes" like nano. You can use metric prefixes with any system (look at the thou for an example - effectively one milli-inch). That is only one part of the metric system; another very important one being the concept of Coherence, which to my understanding basically means that you _very rarely _need arbitrary constants when performing calculations. For example, a watt is *one* joule per second whereas a horsepower is *550* foot-pounds per second.
> 
> The second as a unit is metric in the sense that it is a fundamental part of the metric system of units known as SI and is coherent with the other metric units. It is now defined in terms of things that don't change anywhere in the universe, as are all elements of the metric system (and other elements like the inch that are defined in terms of the metric system).
> 
> ...


I'm off to speak to my accountant......


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## Felix (26 Oct 2020)

Andy Kev. said:


> You learn something every day.
> 
> @ J-G I'd not heard the equator to N Pole thing before and that is of course also necessarily arbitrary. Agreed about basing the metre on the absolute constant of the speed of light (in a vacuum?) but am I not right in thinking that it still does no more than precisely define in absolute terms the the length of the arbitrary metre. We could just as easily determine the foot in terms of the speed of light but it would be no less arbitrary. I'm not suggesting that arbitrary is in any way inferior but the more I think about it, the more arbitrary units of measurement seem to be unless the unit of measurement is itself an absolute e.g. the mass of a proton.
> 
> ...


Who knows what Einstein did dressed in a leather apron on a weekend in a darkened room - only he knew <lol>


----------



## Felix (26 Oct 2020)

Andy Kev. said:


> Try this:
> 
> 
> 
> ...


If time is an unknown phenomenon (introduced by man to rationalize about changes from one event to another) then how can we say that time began at the moment of the big bang?


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## Andy Kev. (26 Oct 2020)

bowmaster said:


> If time is an unknown phenomenon (introduced by man to rationalize about changes from one event to another) then how can we say that time began at the moment of the big bang?


Because it's a component of spacetime. I think the idea is: no space, no time. But that is another notion that we, as creatures of this universe, find hard to accept.


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## Felix (26 Oct 2020)

@AJB Temple If there were dots then surely if they did in fact exist would automatically imply that they were bounded because they would have had some physical size?


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## Andy Kev. (26 Oct 2020)

I'm sure AJB will correct this if it's too far off line, but the idea of the dot is that it is infinitely dense (sort of like oak but more so) and infinitely small which is obviously bonkers because if it has got the whole universe in it and as we can calculate the mass of the universe from observation, the dot is clearly finite. That perhaps speaks in favour of the multi-dot version i.e. lots of universes.


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## J-G (26 Oct 2020)

AES said:


> I can't see why that would be a problem if there was only the two of you


She was a Care Assistant in an old folks home so cakes were often provided by visitors to be shared out


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## AES (26 Oct 2020)

J-G said:


> She was a Care Assistant in an old folks home so cakes were often provided by visitors to be shared out




Yeah, J-G, a LIKELY story!


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## Felix (26 Oct 2020)

Andy Kev. said:


> I'm sure AJB will correct this if it's too far off line, but the idea of the dot is that it is infinitely dense (sort of like oak but more so) and infinitely small which is obviously bonkers because if it has got the whole universe in it and we can calculate the mass of the universe from observation, the dot is clearly finite. That perhaps speaks in favour of the multi-dot version i.e. lots of universes.


This could be a long night........ if there was a multi-dot scenario then what do the scientists believe happened to the others - assuming only one (ours) made it to the big bang would they have been consumed after the event into our universe or would they have gone on to create parallel universes with their own attendant big bangs? I'm off to do some research - quite what this has all got to do with cutting the perfect dovetail I'm yet to discover....


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## AJB Temple (26 Oct 2020)

bowmaster said:


> This could be a long night........ if there was a multi-dot scenario then what do the scientists believe happened to the others - assuming only one (ours) made it to the big bang would they have been consumed after the event into our universe or would they have gone on to create parallel universes with their own attendant big bangs? I'm off to do some research - quite what this has all got to do with cutting the perfect dovetail I'm yet to discover....


There are almost as many theories as dots. The most plausible to me is an infinite number of dots all expanding and contracting simultaneously but not in synchronicity. I can see no real logic for just one dot as our beginning (the start of Big Bang) as if there was one why cannot there be two or an infinite number? Black hole theory seems to explain plausibly the expansion and contraction. If that can occur within one universe (as appears to be the case with many black holes sucking matter in within our universe) then I see no reason why not cannot be true of parallel universes. Time has no real meaning in this construct.


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## billw (26 Oct 2020)

Infinity is definitely one of those concepts that can keep people awake at night. However, I am pleased to say I have solved the issue of how to measure it - it's the amount of wastage I make from a piece of timber whilst machining it into what I thought was the right size.


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## billw (26 Oct 2020)

Droogs said:


> @AJB Temple To put your mind at rest, Before the Big Bang there was just Birmingham



Well, that might explain why there seems to be no escaping the place.


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## Droogs (26 Oct 2020)

IF has been postulated that there are infinite universes and each has it's own density, each akin to that of various species of wood. I'm content I live in an oak one, glad it's not a Lignum Vitae one and feel very sorry for those that live in the Ikea spruce chipboard one


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## Andy Kev. (27 Oct 2020)

bowmaster said:


> This could be a long night........ if there was a multi-dot scenario then what do the scientists believe happened to the others - assuming only one (ours) made it to the big bang would they have been consumed after the event into our universe or would they have gone on to create parallel universes with their own attendant big bangs? I'm off to do some research - quite what this has all got to do with cutting the perfect dovetail I'm yet to discover....


The other dots are probably easy to deal with. Suppose our dot started roughly in the piece of space which your chair is occupying now and it expanded to occupy the space which our (still expanding) universe occupies now. Then suppose that just before our dot began expanding there was another one in roughly the space where your nearest neighbour's telly is standing now but it wasn't ready to expand.

Our dot (= our universe) expands and by definition it must push away anything which is outside it. As far as I can see it's not going to envelope your neighbour's or anybody else's other dots. And if one of those kicks off, it's not going to envelope our dot. That leaves the question of what happens if two dots are expanding in opposite directions head on to each other. Do they exchange material? Does a mixed border region appear? In any event the dots might all be gazzilions of light years away from each other and this whole thing is also in headache territory.

I'd recommend that book I flagged up to AJB. It won't do much to improve your dovetailing though.


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## Andy Kev. (27 Oct 2020)

Droogs said:


> IF has been postulated that there are infinite universes and each has it's own density, each akin to that of various species of wood. I'm content I live in an oak one, glad it's not a Lignum Vitae one and feel very sorry for those that live in the Ikea spruce chipboard one


I bet you've not even thought about worm holes.


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## glenfield2 (27 Oct 2020)

J-G said:


> Quite the opposite. The original definition of a Metre was 1 10millionth of the distance from the Equator to the North Pole along a Great Circle


Don’t forget the ‘through the Paris Meridian’ bit.
As usual we have to blame the French who decided that everything measurable In the universe should be neatly dIvisible by 1000. Them and their revolution, eh.
The rest of us were perfectly happy with our rods, poles and perches.


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## Phil Pascoe (27 Oct 2020)

Which actually are all the same.
I found an excercise book from about 1964 (I was ten) and the sums in it were in miles, furlongs, chains, yards, feet and inches - gallons, pecks and bushels - gallons, quarts, pints and gills - pounds, shillings, pence and farthings. All simple .............


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## AJB Temple (27 Oct 2020)

Phil Pascoe said:


> Which actually are all the same.
> I found an excercise book from about 1964 (I was ten) and the sums in it were in miles, furlongs, chains, yards, feet and inches - gallons, pecks and bushels - gallons, quarts, pints and gills - pounds, shillings, pence and farthings. All simple .............


All that stuff belongs in the Middle Ages. Except feet and inches. Height of men should be measured in feet and inches. I also find that hands for horses makes far more sense than centimetres.


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## AJB Temple (27 Oct 2020)

It's also a weird fact that woodworkers don't like working in centimetres for some reason. They insist on mm except in America obviously as they clearly have a foot fetish. However when I get measured at the doctor, when they are telling me off about my BMI, they don't say you are 1900 mm tall, they say 190 cm. I quite like cm for woodwork.


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## Felix (27 Oct 2020)

Andy Kev. said:


> I'd recommend that book I flagged up to AJB. It won't do much to improve your dovetailing though.


It might help prop up a drawer side whilst marking the pins though <lol>


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## Tim Britton (27 Oct 2020)

re measuring in metric or imperial... some time ago I took a break from writing about old motorcycles and instead did a short piece on my introduction to an alternative measuring system when I was an apprentice joiner in the 70s. The gist of it was the old lad teaching me used nothing more complicated than marks on a stick to deterine hights, widths and depths of whatever was being made. The lesson I learned all those years ago was not to rely on any one system, ergo it doesn't matter which system you use as long as you know what the marks mean. In any case I seem to recall learning in history the English 'yard' was originally classed as the distance from the ruling monarch's nose to the tip of his/her middle finger...


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## AJB Temple (27 Oct 2020)

History is full of old wives tales. It started with Henry VIII


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## Andy Kev. (27 Oct 2020)

Tim Britton said:


> re measuring in metric or imperial... some time ago I took a break from writing about old motorcycles and instead did a short piece on my introduction to an alternative measuring system when I was an apprentice joiner in the 70s. The gist of it was the old lad teaching me used nothing more complicated than marks on a stick to deterine hights, widths and depths of whatever was being made. The lesson I learned all those years ago was not to rely on any one system, ergo it doesn't matter which system you use as long as you know what the marks mean. In any case I seem to recall learning in history the English 'yard' was originally classed as the distance from the ruling monarch's nose to the tip of his/her middle finger...


That point has come up quite a few times. IMO the more you can liberate yourself from numerical measuring of bits of wood, the better the work proceeds. Sometimes it is of course handy to have a number e.g. if for some reason you can't use one piece of wood to mark another and then, as you point out, the System used doesn't matter.

I think that measured plans should only be taken as rough guides e.g. if something is specified at 125 x 63 x 67 mm (unlikely but it could reflect the writer measuring what he has ended up with), then it makes sense to be able to say, "OK, roughly 4 foot by 2 foot by 2 foot". Then you might want to measure your first rough cut of the pieces to 4' 1" but really after the cut to precise length (whatever you may finally settle on e.g. to fit a space) the rest of the measuring is probably a matter for dividers as you are going to be looking for proportionally harmonic bits of wood e.g. 1/2, 1/8, 1/16 of the inital roughly 4' length.


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## Sheffield Tony (27 Oct 2020)

It's all a simulation anyway. We aren't real. This very idea that quantum states only become determined when we observe them - why else would the universe work by lazy evaluation ? And is the speed of light limit a bit like fear of the water in the Truman show - an artificial limit to stop us discovering it's all not what it seems.


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## PhilTilson (27 Oct 2020)

I will not add to the arguments above. As an engineer, I deal almost entirely in metric measurements - and yet, having been schooled during the 50s - I still find that when estimating small distances, it is much more natural to think "that's about three inches", rather than "that's about 7.5cm". However, although I am perfectly happy in both systems, I grind my teeth when I use my favourite graphics program, Serif DrawPlus. This lets you choose either imperial measurements or metric for your drawings. But when you choose the metric scale, you find the sub-divisions are halves, quarters and eighths! Ye Gods!


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## rafezetter (27 Oct 2020)

Andy Kev. said:


> Ah but … the speed of light is an absolute, a bit like a piece of wood: the units in which you choose to measure it- let us compromise on a piece of wood flying through the workshop at less than the speed of light due to frustration at mangling some dovetails - are entirely arbitrary i.e. anything but absolute.
> 
> Gotcha! ( er … I think.)
> 
> Come to think of it, the number of seconds in a year isn't very metric either.



Actually.... it isn't, and never was.

I read in the New Scientist that even though the speed of light is represented scientifically as the letter "C" - it was proven some time ago that the speed of light is altered depending on what it's traveling through - which is obvious when you take the time to think about it, because even photons have mass.

There was an article quite some years ago whereby scientists managed to reduce the speed of light down to a mere 38 mph iirc, a fact that's always stuck with me.

google fu shows this link has the gist of it:





__





Scientists Slow Down Speed of Light







abcnews.go.com





amazing what you can learn while waiting at the doctors!


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## Dr Al (27 Oct 2020)

rafezetter said:


> Actually.... it isn't, and never was.
> 
> I read in the New Scientist that even though the speed of light is represented scientifically as the letter "C" - it was proven some time ago that the speed of light is altered depending on what it's traveling through - which is obvious when you take the time to think about it, because even photons have mass.
> 
> ...



The scientific symbol 'c' is specifically described as "the speed of light in a vacuum" - that's the thing that's a universal constant, not the speed of light generally. It's been understood for many years that it varies depending on medium.


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## bjm (27 Oct 2020)

rafezetter said:


> ... because even photons have mass.
> ...


No they don't


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## britinfrance (27 Oct 2020)

FYI here in France, the inch is referred to as "pouce" (pronounced puss) and features a lot in auto parts, wheel trims for example, and will often appear on powertools, eg bandsaws, where the throat depth will be given inmm and pouce.


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## raffo (27 Oct 2020)

rafezetter said:


> Actually.... it isn't, and never was.


It's not the same in different mediums. Once that is fixed, it is the same regardless of your frame of reference. I think that is the reason, or one of the reasons, why you can't move faster than the speed of light.


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## Cabinetman (27 Oct 2020)

That article on slowing down the speed of light, – – – don’t get me started, absolute zero was in Fahrenheit, haha.


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## J-G (27 Oct 2020)

PhilTilson said:


> However, although I am perfectly happy in both systems, I grind my teeth when I use my favourite graphics program, Serif DrawPlus. This lets you choose either imperial measurements or metric for your drawings. But when you choose the metric scale, you find the sub-divisions are halves, quarters and eighths! Ye Gods!


In that case change your favourite graphics program - get CorelDRAW! - even an older than current version - say 11 - (I'm using X5) will be so much better than any Serif product.


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## J-G (27 Oct 2020)

Cabinetman said:


> That article on slowing down the speed of light, – – – don’t get me started, absolute zero was in Fahrenheit, haha.


Only if you decide to declare it in °F - you could say it is -273.15°C or be totally accurate and say 0 Kelvin - note that is Zero Kelvin NOT zero degrees !! if you must put a degree symbol then you could also use Rankine but then you would be using the Fahenheit increments.


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## stuartpaul (27 Oct 2020)

Andy Kev. said:


> That point has come up quite a few times. IMO the more you can liberate yourself from numerical measuring of bits of wood, the better the work proceeds. Sometimes it is of course handy to have a number e.g. if for some reason you can't use one piece of wood to mark another and then, as you point out, the System used doesn't matter.
> 
> I think that measured plans should only be taken as rough guides e.g. if something is specified at *125 x 63 x 67 mm* (unlikely but it could reflect the writer measuring what he has ended up with), then it makes sense to be able to say, "OK, roughly *4 foot by 2 foot by 2 foot*". Then you might want to measure your first rough cut of the pieces to 4' 1" but really after the cut to precise length (whatever you may finally settle on e.g. to fit a space) the rest of the measuring is probably a matter for dividers as you are going to be looking for proportionally harmonic bits of wood e.g. 1/2, 1/8, 1/16 of the inital roughly 4' length.


And that's exactly what happens when you mix measurements! (sorry Andy, - couldn't resist!)


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## Felix (27 Oct 2020)

bjm said:


> No they don't


I can smell a wave/particle duality debate in the ether.......


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## bjm (27 Oct 2020)

bowmaster said:


> I can smell a wave/particle duality debate in the ether.......


No, it's just that if they had mass they couldn't travel at the speed of light?


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## glenfield2 (28 Oct 2020)

It has always amused me that metric timber and sheet sizes seem to be exactly converted from the old Imperial equivalent (2440 x 1220 being 8’ x 4’ etc).
Does this apply in Europe too where the Imperial conversion has no logic?


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## bjm (28 Oct 2020)

glenfield2 said:


> It has always amused me that metric timber and sheet sizes seem to be exactly converted from the old Imperial equivalent (2440 x 1220 being 8’ x 4’ etc).
> ...


It makes perfect sense if you're in the renovation game. If you had to renew the sheathing on a wall with 16" centres a 1200mm board isn't going to do it! Metrication didn't undo history


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## Just4Fun (28 Oct 2020)

glenfield2 said:


> It has always amused me that metric timber and sheet sizes seem to be exactly converted from the old Imperial equivalent (2440 x 1220 being 8’ x 4’ etc).
> Does this apply in Europe too where the Imperial conversion has no logic?


Not here (Finland) at least. A common size is 2500 x 1250.


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## Phil Pascoe (28 Oct 2020)

I remember being told decades ago that 10' x 5' sheets of ply were available on order in this Country. I never saw one, though.

Flooring sheets and ceiling sheets in different systems (one in one and one in the other) were a nightmare.


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## bjm (28 Oct 2020)

Phil Pascoe said:


> I remember being told decades ago that 10' x 5' sheets of ply were available on order in this Country. I never saw one, though.


They are readily available but I've only ever needed two in the last ten years.


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## Andy Kev. (28 Oct 2020)

2500 x 1500 seems to be the standard size in Germany.

BTW: 14 pages and no mention of dark matter yet. Very sensible.


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## AES (28 Oct 2020)

Yup, 2500 x 1500 seems standard for sheet goods here too.


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## D_W (28 Oct 2020)

billw said:


> It's dawned on me that some tools I have are metric and some imperial. Now I don't particularly see an issue with it, given that the conversions by 16ths are a maximum of less than 0.5mm out either way and the average is about 0.25mm
> 
> Given the only time that these seemingly come into play for accuracy purposes is for chisels and some specialist planes because their blades are imperial, does it actually matter that much or do most people pick one or the other for their tools and stick to it?



it doesn't matter at all unless you're dealing with parts already made and matching them. 

there's a term in the US that must be something similar to what power toolers do - "tool slaving". As in, if you cut a groove with a plane ,then the chisel must match or no work can be done. There's always a way around it. 

I've got gobs of stuff that's probably metric and others that's standard and unless it's marked, I have no clue if something is one or the other.


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## Cabinetman (29 Oct 2020)

Phil Pascoe said:


> I remember being told decades ago that 10' x 5' sheets of ply were available on order in this Country. I never saw one, though.
> 
> Flooring sheets and ceiling sheets in different systems (one in one and one in the other) were a nightmare.


 I was under the impression, probably totally wrong, that they were for making ping-pong tables from!


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## glenfield2 (29 Oct 2020)

bjm said:


> It makes perfect sense if you're in the renovation game. If you had to renew the sheathing on a wall with 16" centres a 1200mm board isn't going to do it! Metrication didn't undo history



Our present house - Victorian with ‘60s renovations (more like butchery) - seems to have been worked on without the aid of a tape measure, metric or otherwise.
And on the older timber frame places I’ve done sheet sizes were the least of my problems
But glad to learn that Europeans don’t follow our weird Metriperial system.


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## Phil Pascoe (29 Oct 2020)

glenfield2 said:


> Our present house - Victorian with ‘60s renovations (more like butchery) - seems to have been worked on without the aid of a tape measure, metric or otherwise.
> And on the older timber frame places I’ve done sheet sizes were the least of my problems
> But glad to learn that Europeans don’t follow our weird Metriperial system.



Ahhhh ............... your house has been Bucknelled.


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## glenfield2 (29 Oct 2020)

Phil Pascoe said:


> Ahhhh ............... your house has been Bucknelled.


Oh yes I remember Barry Hardboard on tv from my youth. The butchery on our place was largely hidden under chipboard floors (how I hate those!) where joists had been attacked by plumbers and electricians seemingly working with hatchets and chainsaws. And had anyone invented the spirit level in the ‘60s!?
Anyway, all sorted now.


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## Phil Pascoe (29 Oct 2020)

In NZ chipboard floors are very common - left bare and varnished, usually with water based PU. They don't actually look bad.

My house (1899) had joists that had been badly notched out, sometimes the notching alternated between the top of the joist and the bottom.


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## Tim Britton (18 Dec 2020)

PhilTilson said:


> I will not add to the arguments above. As an engineer, I deal almost entirely in metric measurements - and yet, having been schooled during the 50s - I still find that when estimating small distances, it is much more natural to think "that's about three inches", rather than "that's about 7.5cm". However, although I am perfectly happy in both systems, I grind my teeth when I use my favourite graphics program, Serif DrawPlus. This lets you choose either imperial measurements or metric for your drawings. But when you choose the metric scale, you find the sub-divisions are halves, quarters and eighths! Ye Gods!


Phil, I occasionally wonder at the thought process of program designers who, as you say, subdivide metric measurements with imperial references... a similar thing occurred when sheet material manufacturers were transitioning from totally imperial to totally metric dimensions and there was a period when a sheet of plywood coulkd well have one measurement in imperial and the other in metric... of course us site joiners, purely for amusement, would occasionally send a request to the stores for 3m of 4 x 2... or 6ft of 50 x 50.


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## TRITON (18 Dec 2020)

Oooooh this is a long thread.

I'll chuck in my tuppence worth.

Like many Brits I think or gauge height, length in imperial. say about 5' high, or 6' wide, but when it comes down to making such I go metric as its usually easier to sub-divide in units of 1/10/100.


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## SteL (18 Dec 2020)

As others have mentioned, I seem to vary on this depending on the size. For visualising small things - like the thickness of my wallet after checking what's new on Tooltique, I use mm. I struggle to visualise 1/8, 1/16 etc. For hand-sized to arm-sized things like my pastie that I'm just about to demolish, I think in inches. Then, things bigger than that but smaller than me I can visualise ft better, and anything a lot bigger than me I tend to go with metres. Not sure why. Maybe it is because it's easier to compare some things. I've used loads of 6" nails, so I can visualise that and I know what a 12" rule looks like. I think more people in the UK know their height in ft rather than cm/m. Must be something to do with that! If I'm drawing something out and not trying to visualise it, I'll use metric, though. What a sellout!


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## Peri (18 Dec 2020)

Tim Britton said:


> .........of course us site joiners, purely for amusement, would occasionally send a request to the stores for 3m of 4 x 2... or 6ft of 50 x 50.



In #126 of this thread I wrote about examples of official NASA documentation that says things like "The cross-bar is 4.82 metres long, and has 15 3/8's inch holes spaced 32mm between centres" haha 

(But tbh, I wouldn't think twice about asking for 6ft of 50x50mm  )


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## Spectric (18 Dec 2020)

Try to use mm as it should be easier, but at the same time a lot of stuff is manufactured using imperial and given a metric size. Sanitary ware is a good example, recently a drawing showed 83mm and you know this is really imperial at 31/4 inches because you would not design to 83mm but 80mm or 85mm. Sometimes without thinking I give a measurement as say 400mm by 9 3/8 as it fits nicely. When taking my own measurements I often end up writing it down as something like 8 1/2 + 1/16 to make sure it is too tight rather than loose, you can always skim a little more off but cannot put it back.


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## deema (18 Dec 2020)

MikeG. said:


> Really?
> 
> I have a bannister 4'-10 3/8" long and want to space the 12 ballusters out equally. What's my spacing?
> 
> Whilst you're doing that, I'll divide 1483 by 13 and then go and make us both a cup of tea. You might be done by the time I'm back.




Clearly blinking shoddy workmanship using metric if you are dividing 1483 by 13. By my ruler it’s 1482.725 by 13 which gives 114.055769mm centres. Now I’d like to see that metric ruler!

I do have one that has 1/64 resolution though!


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## Boringgeoff (19 Dec 2020)

Well I just read this whole thread again because it's 34C (that's hot in F) outside and there's work to be done when it cools off. 
No mention of rain gauges so far. When I was a kid in NZ we had an official rain gauge on the farm and Dad or Uncle had to read it and record the result. Measured in inches with increments of 100 points, you'd hear the old man tell our neighbour "we got 132 points overnight".
Now in retirement I've been measuring the rain for thirteen years, with a metric gauge, measures in mm. I record to the nearest .5 of a mm. 
Cheers,
Geoff.


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## jcassidy (19 Dec 2020)

bjm said:


> No, it's just that if they had mass they couldn't travel at the speed of light?



If light has no mass, how does gravity affect it???


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## Phil Pascoe (19 Dec 2020)

Spectric said:


> When taking my own measurements I often end up writing it down as something like 8 1/2 + 1/16 to make sure it is too tight rather than loose, you can always skim a little more off but cannot put it back.



I worked with a (now long dead) chippie who always said full or scant when giving a dimension so you knew on which side to err.


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## Phil Pascoe (19 Dec 2020)

Peri said:


> In #126 of this thread I wrote about examples of official NASA documentation that says things like "The cross-bar is 4.82 metres long, and has 15 3/8's inch holes spaced 32mm between centres" haha


I worked with a chippie who would come out with gems like - 
I need a piece of 3/4" ply about 18" wide and a exactly a metre long. It needs a housing cut in it, 6" from the edge 12mm wide and 3/8" deep.


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## Cabinetman (19 Dec 2020)

Phil Pascoe said:


> I worked with a chippie who would come out with gems like -
> I need a piece of 3/4" ply about 18" wide and a exactly a metre long. It needs a housing cut in it, 6" from the edge 12mm wide and 3/8" deep.


 Perfectly understandable Phil, just means he was bilingual like me ha ha


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## mccpe (19 Dec 2020)

jcassidy said:


> If light has no mass, how does gravity affect it???


Light travels through space time which is warped by gravity. So gravity doesn’t directly act on light, as far as light is concerned, it’s going in a straight line. Gravity makes those straight lines bend.

it’s a bit early for this!


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## Just4Fun (19 Dec 2020)

Phil Pascoe said:


> I worked with a (now long dead) chippie who always said full or scant when giving a dimension so you knew on which side to err.


I worked on building sites as a part time job when I was a student and the terms there were FULL and BARE.


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## Cabinetman (19 Dec 2020)

When I write a measurement that isn’t exact say, 562 mm + or -, which means just lean the pencil one way or the other, we used to have a measurement called a knats bod.


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## Awac (19 Dec 2020)

I like imperial, I find it easier to see, 1/8th and 1/16th are usually the smallest I need. I like the brain work out when converting fractions, imperial is a little more challenging, but easy to divide in the kind of units I use. I can also remember inches easier, why, I have no idea.
I have attached the Lufkin story of measurement, I put it on another post but maybe some of you have not seen it.


A guy called Sam Doohan wrote this in Quora on the web: I have pasted some parts. I think he makes some good points. Easy division for daily life with Imperial, but metric makes sense in scientific circles.

_"The imperial system is designed for people with minimal schooling and who have to think about day to day physical objects in the real world that are not easily divisible into very small fractions. We work vastly better thinking in whole numbers and we can handle much more complex mathematics when we are working from simple whole numbers".
"Base 12 is much easier for normal people handling small numbers but is far less ideal for anyone working in very large numbers.In science where we are talking about huge numbers or tiny numbers decimal helps us in thinking about things because something like 8*10 gives a round number where in base 12 it doesn’t. That’s why we changed to decimal stuff for many things, and why scientists in the US use meters and kilograms."

"You can even count on your fingers in base 12 (you count on the segments on your fingers)!" 

"Don’t presume that imperial units are stupid just because you weren’t brought up to use them. There’s reasons for them and while maybe we’ve grown past the point where those reasons are all that big of a deal to us they served their purpose well for a long time. The fact that you can build battleships and fighter planes (as Britain and the US did) off the imperial system illustrates that these systems are just as accurate and effective. They are much less suited to a computerized, technologically focused world but they aren’t random or wrong; just made for a different time"._


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## eribaMotters (19 Dec 2020)

I cannot understand all the faff about converting mm to fractions of an inch or vica versa and complaints about unmanageable readings.
I buy in my stock by whatever units the dealer uses and when making just use whichever lines up with my ruler or tape measure.

Colin


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## Tim Britton (7 Jan 2021)

Phil Pascoe said:


> I worked with a (now long dead) chippie who always said full or scant when giving a dimension so you knew on which side to err.


yes, that's something I recall from my time working with old guys when I was an apprentice, a measurement would be either 'scant' or 'good' to determine where to cut.


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## Terry - Somerset (10 Jan 2021)

The UK Government endorsed metrication in 1965. 
In 1971 £, shillings and 240d became £ and 100p.
In 1994 gallons of petrol became litres
In 1999 a pound of potatoes became 0.453592kg

And it is still a shambolic mess - beer in pints, 8x4ft sheet material is now 2440x1220mm, speed limits are mph.

Perhaps following Brexit we should revert to imperial to sit alongside blue passports. 

It only took 55 years to get close to alignment with our european friends, going in the opposite direction will, I am sure be quicker, suit us oldies, but upset the kids.


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## pcb1962 (10 Jan 2021)

Terry - Somerset said:


> going in the opposite direction will, I am sure be quicker, suit us oldies, but upset the kids.


Not just the kids, I'm 58 and it would sure upset me.


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## JoshD (10 Jan 2021)

Well this is a long thread, and I speak as someone who is mostly metric, but no-one has mentioned nautical units where frankly the old units win hands down. You see a nautical mile (nm) is equal to one minute of latitude (1 minutes here is a measure of angle, 1/60 degree). And it turns out that a nautical mile is near as dammit 6000 feet. 6000 feet is a lot easier to work with than 1852m or whatever. And it gets easier still if you switch to fathoms, 1 fathom being 6 ft, so a nautical mile is 1000 fathoms.

So here you have a system of units that links the human size to that of the planet.

For example, I know that

* the circumference of the earth is 360*60=21,600nm.
* If I am at latitude 50° 12.345' N and you are at 50° 12.346' on the same longitude then we are 1/1000 of a nautical mile apart, ie 1 fathom or 6 feet.
* If I coil my ropes so that each turn is from outstretched hand to outstretched hand, pretty much a fathom for most people, then the counting the coils of a stored rope gives me its length in fathoms.

A cable is 1/10 nm, ie 600ft or 100 fathoms; on my boat that's about 16 boats lengths.


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## Bodone (10 Jan 2021)

If you’re doing Knots, then what about AU’s?


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## Just4Fun (10 Jan 2021)

JoshD said:


> A cable is 1/10 mm


Was that a typo or was auto-correct being over-zealous?


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## JoshD (10 Jan 2021)

Bodone said:


> If you’re doing Knots, then what about AU’s?


AU, as in Astronomical Units? 93M statute (ie, regular) miles is about 82M nm, so at 6kn my boat will take .... a long time to do 1AU


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## JoshD (10 Jan 2021)

Just4Fun said:


> Was that a typo or was auto-correct being over-zealous?


Fixed!


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## Terry - Somerset (10 Jan 2021)

We are part of a globally integrated technologically advanced community, yet have been unable to create a common language for scientific, technical and objective measurement.

sailors do things differently mixing metric (1000 fathoms) with imperial (6ft)
nautical miles are different to land miles
but I think a nautical foot is the same as a land foot
a US gallon is different to a UK gallon (6.66 vs 8 pints)
most of the world uses litres anyway
fortunately ton and tonne are spelt differently (but sound the same)
but a US ton is 907kg, a UK ton is 1016kg. A tonne is 1000kg
It is somewhat surprising that international collaborations ever work - most do but there have been some spectacular and costly foul ups.


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## bourbon (10 Jan 2021)

Like smashing a space probe into a planet?


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## Mead Camans (10 Jan 2021)

I'd just like to jump in here with a little metric fact that I love, which is that a metre is defined as the distance that light travels in a vacuum in 1/299792458 of a second.


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## Droogs (10 Jan 2021)

even building 2 halves of a rocket on different continents and then only finding out 1 was metric the other imperial when one bit wouldn't fit inside the other bit- oops (that one was genuinely my wife's cousin)


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## JoshD (10 Jan 2021)

Mead Camans said:


> I'd just like to jump in here with a little metric fact that I love, which is that a metre is defined as the distance that light travels in a vacuum in 1/299792458 of a second.


So the speed of light is pretty nearly 1 foot/nanosecond, pretty handy to know


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## J-G (10 Jan 2021)

Since the figure quoted is close to 30% of a nanosecond for nearly 3-1/3 feet it's much closer to 10 feet per nanosecond.


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## billw (10 Jan 2021)

At least the world agrees about times and dates. Although it’s currently 10 January 2564 in Thailand, so maybe not.


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## Droogs (10 Jan 2021)

at least they agree it is January unlike the Russians


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## Deadeye (10 Jan 2021)

JoshD said:


> AU, as in Astronomical Units? 93M statute (ie, regular) miles is about 82M nm, so at 6kn my boat will take .... a long time to do 1AU



Well, if we're having Astronomical Units we're going to have to put the Siriometer in place as well.

And the Slug for mass (just under 15Kg)

And for people picky about angles, what about the Furman (about 1/65,000th of a degree0

And the Barn-megaparsec for volumes (about 1.5ml)


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## stuckinthemud (10 Jan 2021)

I speak bilingual, but the system of 12 works in shops/stalls where half, quarter and third were important , I always used to buy 1/4 of sweets, even a ten year old could calculate the price of a fraction of goods priced by the pound in weight, ten is easy to divide by ten, but try quartering it.


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## Droogs (10 Jan 2021)

@Deadeye You just made that last one up. There are no such thing as amish space farmers

@stuckinthemud that was the beauty of the old £ - 240 is a very special number


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## billw (10 Jan 2021)

stuckinthemud said:


> ten is easy to divide by ten, but try quartering it.



Ok here's my go - it's 2.5


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## stuckinthemud (10 Jan 2021)

Ok, so pear drops are £3.60 a pound, how much is 1/8?


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## stuckinthemud (10 Jan 2021)

Now, ccalculate .125 of £3.6


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## stuckinthemud (10 Jan 2021)

Actually, that should be £3.60/2.5/.125 (I think)


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## Droogs (10 Jan 2021)

is that an 1/8 of a pear drop or an 1/8 of a lb or £


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## stuckinthemud (10 Jan 2021)

Well in the old days, we lived in a cardboard box in't gutter...an 1/8 of a pear drop were luxury just for birthday


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## billw (10 Jan 2021)

stuckinthemud said:


> Now, ccalculate .125 of £3.6



45p. This isn't mentally draining stuff for an accountant btw


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## J-G (10 Jan 2021)

stuckinthemud said:


> Ok, so pear drops are £3.60 a pound, how much is 1/8?


9 bob!


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## stuckinthemud (10 Jan 2021)

Fair 'nuff, point still stands, system of 12 works in a society where most people had a limited education, if they had any education at all


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## billw (10 Jan 2021)

stuckinthemud said:


> Fair 'nuff, point still stands, system of 12 works in a society where most people had a limited education, if they had any education at all



TBF I worked the second one out simply by halving it three times.


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## stuckinthemud (10 Jan 2021)

Wish I was that clever


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## JoshD (10 Jan 2021)

J-G said:


> Since the figure quoted is close to 30% of a nanosecond for nearly 3-1/3 feet it's much closer to 10 feet per nanosecond.


1/300,000,000 seconds is 3 1/3 nanosecond not 0.3 nanoseconds. Google gives speed of light as 0.9857 feet/nanosecond


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## Phil Pascoe (10 Jan 2021)

Imperial is best. Five eights of f. a. sounds much better than 0.625 of f. a.


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## J-G (10 Jan 2021)

JoshD said:


> 1/300,000,000 seconds is 3 1/3 nanosecond not 0.3 nanoseconds.


I looked long and hard at that in the first instance (didn't Google) and 1 nanosecond is 1/1,000,000,000 sec. which makes 1/300,000,000 / 1/1,000,000,000 = 0.3ns. and there isn't an SI unit of 1/90,000,000 that would be needed to make 1/300,000,000 sec. 3 1/3 ns.

But I'm now totally confused because as you have correctly pointed out Josh, Google does say light travels 1' in 1 nanosecond ????

So, I have something wrong but can't see what!

[EDIT] D'oh !!! I'm upside down !!


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## JoshD (10 Jan 2021)

J-G said:


> I looked long and hard at that in the first instance (didn't Google) and 1 nanosecond is 1/1,000,000,000 sec. which makes 1/300,000,000 / 1/1,000,000,000 = 0.3ns. and there isn't an SI unit of 1/90,000,000 that would be needed to make 1/300,000,000 sec. 3 1/3 ns.
> 
> But I'm now totally confused because as you have correctly pointed out Josh, Google does say light travels 1' in 1 nanosecond ????
> 
> ...


Yep, you were upside down, so easy to do!


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