Metric 'thou'?

I would have thought that for tolerances, you would find the metric equivalent of the "gnats c*ck" rather more useful

Regards, Tony

Reply to
Tony Jeffree
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Gnat's c*ck flaccid, or gnat's c*ck rampant?

Regards,

David P.

Reply to
David Powell

Tony Jeffree wrote ...........

To which David Powell wrote in response .................

Could it be that 'rampant' and 'flaccid' are the top and bottom limits of the tolerance?

Mike

Reply to
Mike Whittome

I thought something smelt a bit odd. ;)

Mike

Reply to
Mike Whittome

Sounds like a pretty tight tolerance to me ;-)

Regards, Tony

Reply to
Tony Jeffree

In engineering/workshop practice, the metric unit used for these measurements is usually the "hundredth", or 1/100 of a mm = 10 microns. The 'thou' is equal to 2.54 "hundredth"'s.

I prefer the micron myself, 1/10th as big as the "hundredth" - a "thou" is equal to 25 microns.

"Within a few tenths (of a thou)" translates roughly as "within a hundredth", or "within 10 microns".

Reply to
pete

Thanks; a hundredth also seems like a useful unit!

Dave

Reply to
Dave A

Not quite. The preference for powers of 3 prefixes can be attributed to many organisations. But the SI authority

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has no stated preference.

Reply to
pat.norton

Normalised notation and engineering notation are well described at

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and

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Getting these wrong are sure fire ways to lose grades in your work at uni.

Reply to
brightside S9

Centimeters are for dressmakers and BBC announcers and fall into the 'other' measurement units used by these morons. Like it's 3 football fields long, fine if you knew the British Standard for a football field. Looked on the back of my starret ruler and it had mm to in, litres to gallons but no football fields to shuttle launch vehicles.

Oh well another flat battery in the car park of life.......................

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

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Reply to
John Stevenson

But isn't there some vague conection between horse-drawn carts and roman roads to shuttle launch vehicles?

Peter

Reply to
Peter Neill

from John Stevenson

Unfortnate choice of reference there John.

There is no British (or any other) Standard for the size of a football field.

A month after buying my first house (1972) I had a note through the door telling me that the council were preparing to pull it down to re-develop the area and provide a football field for the local school. I won't bore you with the detail but I became chairman of the fighting committee and my research to find out how big a football field was brought zero results.

Even then ratio of length to width is not defined - though I think that the goal size might be!

JG

Reply to
JG

Hm quite right, I never knew that, have been labouring under a misapprehension. It is however a slightly odd prefix, in that although the centimetre is universally recognised, the centigram, for instance, is rarely used, as are other centi-units, and even the centimetre is frowned upon in official circles in the USA.

David

Reply to
David Littlewood

The US do use the centi-dollar quite a lot, though :))

Dave

Reply to
Dave A

Doesn't buy a lot though.

David

Reply to
David Littlewood

Neither does the Dollar, come to that.

Regards, Tony

Reply to
Tony Jeffree

d$4665ba20$d4bb5625$ snipped-for-privacy@news.chello.nl...

cht

An imperial inch is 25mm exactly.

A metric inch however, is only 25mm.

:-)

Hywel

Reply to
hyweldavies

2cd$4665ba20$d4bb5625$ snipped-for-privacy@news.chello.nl...

richt

My weak joke didn't come even out right...

Meant to say, imperial inch is 25.4, but the "new" metric inch is 25mm exactly.

Sorry, I'll get my coat.

I'll have to try this on the letters page of the Daily Mail saying it's the new Euro-inch. Bet they publish it.

Hywel

Reply to
hyweldavies

I think we should all change to the FFF system of units - see:

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Expressing speed in furlongs per fortnight (approx centimeters per minute) is particularly appealing ;-)

Regards, Tony

Reply to
Tony Jeffree

Reminds me of a collegue who, when asked "how long's a nanonsecond?" held his fingers about a foot apart, and said "about this long". Took me a good few seconds to realise he wasn't being silly: he was an electronic engineer. Even more valid now meter is officially defined in terms of time, rather than wavelengths of such-and-such.

Physicist define mass in terms of electron volts - and if I recall correctly that isn't just in terms of energy (E=mc2), but has an additional in-built fudge factor you're expected to know (mass of whatever particle I think) - though might be wrong on the last point.

Another confusing one I've heard of but not seen, is a tape measure graduate in feet and tenths. Catches out those of us expecting inches.

But then, tyre sizes are typically mm across and inches diameter.

And (British) BA screws are a metric thread, and (German) DIN diving valves are 5/8" (or something) BSP.

Hywel

Reply to
hyweldavies

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