Rulers.

[Phil Pascoe]

I used a ruler I've owned for about 40 years, it's so faint I can hardly see it. Why do I do this with an item that costs so little, I asked myself. I threw it away. I picked up another, it was marked imperial on the bottom, which for me is inconvienient, and also marked in 10ths. It'll do for a moment I thought. Made in China, but clear enough. I measured something, it wasn't quite right. I measured again. Not quite right. It wasn't marked in 10ths, it was marked in 12ths. Why???? Thrown away.

 

[Spectric]

I find imperial and metric can be useful, sometimes when being exact is less important then if you get a bang on imperial measurement rather than an odd metric one it is easier to both see and remember, maybe because I grew up pre metrification !

 

[paulrbarnard]

I used a ruler I've owned for about 40 years, it's so faint I can hardly see it. Why do I do this with an item that costs so little, I asked myself. I threw it away. I picked up another, it was marked imperial on the bottom, which for is inconvienient, and also marked in 10ths. It'll do for a moment I thought. Made in China, but clear enough. I measured something, it wasn't quite right. I measured again. Not quite right. It wasn't marked in 10ths, it was marked in 12ths. Why???? Thrown away.

Serious question. Why would you want one marked in 10ths? 1/16ths would be best. If working in decimals then the metric system is the way to go. The whole beauty of imperial is the fact that the fractions divide. Half of a half is a quarter, half of a quarter is an eighth. Half of an eight is 1/16. 12ths would let you measure thirds so that could be useful but less so than halves.

 

[Jacob]

Serious question. Why would you want one marked in 10ths? 1/16ths would be best. If working in decimals then the metric system is the way to go. The whole beauty of imperial is the fact that the fractions divide. Half of a half is a quarter, half of a quarter is an eighth. Half of an eight is 1/16. 12ths would let you measure thirds so that could be useful but less so than halves.

I reckon imperial evolved for people who were making and measuring things, and metric for people who were counting things, (accountants etc. fingers helping).

 

[Stuart Moffat]

I have two 1M rulers, one aluminium the other steel, both presents. for some reason both have metric down one side and imperial down the other. Turn them over and that pattern is repeated. I was putting in some new, deep window boards last week and wanted them to fit precisely (trim and silicon is a bodge!). I knew the window was not quite in the same plane as the internal wall, so needed to measure the depths exactly at the edge. The only way to do that with my rulers is to use imperial for the left hand side, and metric for the right. It’s amazing how often I have readings like spectric’s… say 5” X 15mm etc.
stuart

 

[paulrbarnard]

I have two 1M rulers, one aluminium the other steel, both presents. for some reason both have metric down one side and imperial down the other. Turn them over and that pattern is repeated. I was putting in some new, deep window boards last week and wanted them to fit precisely (trim and silicon is a bodge!). I knew the window was not quite in the same plane as the internal wall, so needed to measure the depths exactly at the edge. The only way to do that with my rulers is to use imperial for the left hand side, and metric for the right. It’s amazing how often I have readings like spectric’s… say 5” X 15mm etc.
stuart

I have Starrat rulers which have the marking in opposite directions on one side and the mirror image on the other side. This means you can use either edge of the rule and simply flip it over to have the measurement going in the opposite direction. Very good design as you can always get a scale in the orientation that works best.

I don’t like the combined metric and imperial rules. And have separate versions.

 

[Sideways]

It would be interesting to try working for a few weeks with an unnmarked straightedge that had a ruler stop, plus just a tape measure. Plus the usual squares and gauges...
I'd argue that on parts under (say) 600mm which is a very useful length of steel rule, it's nice to have repeatability of better than 0.5mm and a ruler stop is the way to get that most easily.
As many folk have pointed out, for woodworking the absolute dimensions aren't usually that critical - a tape marked in mm can be interpolated by eye to close on 0.5mm and that's near enough 1/51st of an inch.
What matters to me is being able to repeat measurements so I can get things square and parallel.

Using a metric tape or rule, I like them with the 10's highlighted and a longer tick mark at the 5's too. If I'm transferring measurements not writing them down in between I read the tape to the nearest 5 and just hold in my head that I should count one or two mm graduations up or down from the 5. Does anyone else's head work like this ?

 

[paulrbarnard]

Using a metric tape or rule, I like them with the 10's highlighted and a longer tick mark at the 5's too. If I'm transferring measurements not writing them down in between I read the tape to the nearest 5 and just hold in my head that I should count one or two mm graduations up or down from the 5. Does anyone else's head work like this ?

That’s me too. I’m badly dyslexic and have a pictorial memory rather than descriptive so I tend to know what it looks like rather than what it actually says. If I verbalise it it comes out as something like two marks past the 20

 

[mccpe]

As many folk have pointed out, for woodworking the absolute dimensions aren't usually that critical - a tape marked in mm can be interpolated by eye to close on 0.5mm and that's near enough 1/51st of an inch.

I find metric rules, which usually have at least the first 5 to 10 cm marked in 0.5 mm graduations pretty much impossible to use with my eyesight. For almost everything, an imperial rule marked down to eighths is going to be fine and is very easy to read. Nothing finer than sixteenths is really necessary on a rule for woodwork, and I would usually switch to digital calipers for anything finer - like checking the thickness of stuff from the thicknesser.

My most used rule has 4R graduations - see here for a list of the (US) graduation styles. The worst rules in my opinion are those that have metric, decimal inches (i.e. tenths) and imperial (i. e. eighths, sixteenths, etc) all on the same rule. The metric scales are too hard to read at the lower end because of the 0.5 mm graduations, and it is too easy to accidentally measure in tenths of an inch when you meant to measure in eighths.

 

[SammyQ]

I reckon imperial evolved for people who were making and measuring things, and metric for people who were counting things, (accountants etc. fingers helping).

Nope. Imperial is what it says on the tin; a hangover from British Imperial times. Metric measurements enable values from length, volume, yada yada to be more easily incorporated into formulae. My old chestnut to illustrate this is the value of Ψ vs diffusion pressure deficit. Ψ is easy, dpd requires a correction 'constant' which introduces a possibility of error. Same arguement holds for a lot of scientific calculation. S.I. rocks.

 

[clogs]

sammyQ
ur wasted here.....
I cant find the trident on my keyboard let alone the meaning.....lol......

 

[XTiffy]

In my apprenticeship (Royal Navy), we used rules marked imperial in 1/64ths and callipers. We did not use mikes but the examiner did. Now I can barely distinguish 1/16ths. I am perfectly happy with metric or imperial but as imperial is more "pictorial" I find it easier to "hold" it in my head. Much as Paul Barnard describes (and I am not dyslexic). With metric tapes it is so easy to mark 10cm out say 1009 rather than 1090!

 

[J-G]

The Ψ is simply the Greek letter Psi - used in many mathematical formulæ, so it's meaning is context dependent.

I can't type it directly either so I just did a "copy'n'paste" - if it were possible to select a particular typeface in the middle of a post then you could use 'Symbol' to access all the Greek letters.
π - Ω - λ - δ - Σ are all copied from a .PDF file displayed on screen - the same cannot be done from an Excel spread-sheet or a Word document though.

 

[eribaMotters]

I'm surprised nobody has picked up the fact that we use a rule and not a ruler.
As regards the 10th's of an inch, it would suggest an American origin. They were responsible for the spacing on pre-drilled circuit boards, which is a 1/10th inch grid.

Colin

 

[Jacob]

Nope. Imperial is what it says on the tin; a hangover from British Imperial times.

The name may be a hangover but the idea is a lot older. Maths began as geometry and arithmetic, two distinct approaches

 

[Woody Alan]

"I'm surprised nobody has picked up the fact that we use a rule and not a ruler."
It certainly popped into my head having had it beaten into to me in my schooldays, but had a feeling it has been accepted into common language. I looked it up and got it "off of" the interweb and it appears so.

 

[Adam W.]

Serious question. Why would you want one marked in 10ths? 1/16ths would be best. If working in decimals then the metric system is the way to go. The whole beauty of imperial is the fact that the fractions divide. Half of a half is a quarter, half of a quarter is an eighth. Half of an eight is 1/16. 12ths would let you measure thirds so that could be useful but less so than halves.

It's an americanian thing 1/10ths, then they can happily use 1000ths without missing the moon by a million miles when they shoot rockets at it.

 

[niall Y]

I wonder to what extent the subdivision of the inch was something that varied across Europe. I suppose that the subdivision into eighth and sixteenth, etc, is something that we are used to in the English speaking part of the world, though logically speaking 1/12ths would make a lot more sense
I have an old Elektra Beckum planer ( Made in Germany) and the graduations for the scale are marked in 1/24ths,
Supposedly the foot measure was based on Emperor Charlemagne's own foot which was closer to 13 inches though the actual size of a foot was never fully standardised even across the whole of France by the time of the introduction of the metric system.

As for dividing an inch into 1/10ths, well if we keep on subdividing , we get to our much loved thou, for which we might have to thank a certain Mr Whitworth.

 

[worn thumbs]

It's an americanian thing 1/10ths, then they can happily use 1000ths without missing the moon by a million miles when they shoot rockets at it.

If you ever have dealings with American engineers,they are likely to refer to the measuring stick as a "scale".
I agree with Sammy Q that SI makes the calculations easier,who misses slugs and poundals?
For accurate work I use a Rabone 64R with both metric and imperial and I try to stick to one or the other.

 

[deema]

I think my teachers preferred the Roman numerical system, I used to get a lot of 10’s, or so I told my parents