How should we describe non-metric tooling?

You learn stuff from threads like this

I never knew a chain existed until now and it's relationship to acres(area) as well as miles(distance) and cricket pitches

If I read things right a square acre is 208.7 feet on the side

Edited By Ady1 on 02/06/2017 09:09:31

Just like Anthony Knights, I was brought up on feet & inches in the 1940's & 1950's. And I suffered with CGS/MKS & now SI, or whatever it's called. I rather think it was in the 1950's that I learned about metric, and since then have gradually changed over to metric such that I now think automatically in metric, indeed it is getting to the state when inches/feet/yards seem somewhat alien now.

The important thing is to be aware that there are these different measurement systems, and to be able to convert between them - if necessary.

One comment about BA. BA is the specification of the entire series of nuts/bolts & threads. There is no need to specify bolt sizes, thread pitches, or anything else - eg 6BA specifies everything - other than length, and therefore all you need are the appropriate BA sized spanners/sockets/whatever.

A storm in a teacup, say I.

Peter G. Shaw

Ah Ady! Its good to be young as us older ones learnt 22 yards = 1 chain etc etc at junior school, much like our times tables. Can you have a square acre? You may have a square of land which is an acre, but if it were any other shape, it could be an acre.
BobH

Nobody has mentioned the names We give the wrenches (and wenches) when they slip!

At least with all these standards they are in English, the Japanese have to contend with "1/4" Whitworth" in their camera manufacturing industry.

John

Interesting concept a square acre. Now a square metre, or m², is a metre in each of two orthoganal dimensions. A square acre must be an acre² and thus needs to involve the third and fourth dimensions?? Time travel anyone?

Russell.

To be a mega-pedant, each side of an acre enclosed by a square would be roughly:

208.7103255711130359119269739325594232254906391954643105725953202843\
11232950189722608720375153033819482364920754087443639804224498009956\
08096957429338221015762076482937383115608350391012929148040595218963\
09173520879711240464289283710200180944953682561606725329621948176844\
97941827390421237419579465909626746184510686264757590949878436627799\
56910405162029438631060308690686355005548877608835027208787025477461\
32619584965464083310276077445636167361202603866905059156109265411382\
7990328478104869507239647431

feet long. This looks suspiciously like an irrational number.

In the US, two different definitions of the yard exist when defining an acre, the yard and the survey yard. Apparently, it's not agreed that the survey yard actually exists. So it's 0.999 998 of an exact yard, hypothetically.

There's never been any particular expectation than an acre would be square; rather the definition assumes certain special rectangles or irregular areas. Better to think in terms of the area that could be ploughed by a yoke of oxen. No-one expects to acres to be measured accurately.

Clear?

, Dave

PS. Aren't expressions like 'square foot' bad grammar? It's surely more correct to say 'foot squared', in which case Ady1's use of 'square acre' is irreproachable.

Edited By James Alford on 02/06/2017 17:40:46

Edited By James Alford on 02/06/2017 17:41:15

Yes , a square acre is a four-dimensional hypersolid. One square acre could be a hypercube with vertices at 0,0,0,0; 0,0,0,1 etc. through to 1,1,1,1. If you want to visualise it you can make a representation in the form of a three-dimensional solid. This is the same principle as representing three-dimenional solids in two dimensions by using perspective drawings.

I suppose you could represent the three-dimensional representation of the four-dimensional hypersolid with a stereo pair of two-dimensional views, but that might be taking it a bit too far.

Geo.

I suspect that "twelve feet squared" might actually be 144 square feet? Just a thought....

... and all this just because I don't agree that American standards ought to be called 'imperial' ...

A strange world indeed.

Tim

It was explained to me by an older chap at B&Q who was glad I had metric measurements - in his case the inches scale had worn off!

Neil

Think you will find they have been 1/4 UNC for years

Steve

Does anyone care? for a low load situation like this it doesn't matter

.

Quite true, Steve

and, as discussed on this forum several times before; the specified 'fit' is sufficiently loose to make it "compatible" with 1/4" Whitworth. ... Such is 'progress'

MichaelG.

Why do we still have Imperial time clocks?

we don't, hours minutes and seconds are worlwide, dating from the time of the Babylonians I think, although there have been attempts at decimal time

**LINK**

I have a clock machine that stamps with a 100 minutes to the hour. This was to aid costing jobs.

A little light reading: **LINK**

http://www.legislation.gov.uk/ukpga/Geo4/5/74/contents/enacted

This is the Act that introduced what became known as British Imperial Units.

MichaelG.