Imperial vs Metric

[t8hants]

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.

 

[MusicMan]

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.

 

[MikeG.]

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.

 

[Cheshirechappie]

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!

 

[Cheshirechappie]

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!

 

[Yojevol]

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

 

[MikeG.]

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

They don't.

 

[billw]

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

 

[Dr Al]

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".

 

[NickM]

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...

 

[Phil Pascoe]

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.

 

[Phil Pascoe]

... 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.

 

[MikeG.]

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

Sorry.

 

[Jonzjob]

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 buggers 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.

 

[MikeG.]

......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.

 

[Dr Al]

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]

 

[Dr Al]

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.

 

[large red]

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

 

[TheTiddles]

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

 

[Astrobits]

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!
https://en.wikipedia.org/wiki/Mars_Climate_OrbiterStick to one system.
Nigel