Thread: Stupid Imperial Measure Question

Cheers Ian. It was obvious to break a circle into 400. It just another example of where a metric standard failed to take hold. Just like time my current 24 hour time is 9:18 we’re in 20 hour metric time it’s 8:87.

Originally Posted by ian

Base 12 measurement systems are much more flexible that base 10 systems.

10 can be readily divided into halves or fifths, but 12 can be evenly divided by 2, 3, 4 and 6 -- a much more flexible approach.

From my limited understanding imperial uses fractions of 2 and 3 and 4 and 6 and 9 and 12 and 16 and 32 and 64 and 128 and a 1000. Plus probably many more.

The thing that I struggle with is the fractions. The basic math like 1” - 1/4” = 3/4” is easy however something like 3/64” - 7/16” = I would have no bloody clue.

However 25mm - 17mm + 0.237mm = 8.237mm and no fingers.

Originally Posted by thumbsucker

Cheers Ian. It was obvious to break a circle into 400. It just another example of where a metric standard failed to take hold.

that is a too simplistic observation.

400 grads is useful in that a right angle is 100 grads, so if you are following a compass bearing of 37 grads, turning 200 grads to your right or left will take you back along your original path.
but it is not particularly useful for triangles where the internal angles add to 180 (in degrees). as a multiple of 60, 180 has many more divisors than 400.


Nautical miles persist for navigation in part because 1 degree is approximately equal to 60 Nautical miles, with 1 minute of arc equal to 1 nautical mile.
So after measuring an angle, you know the distance without needing any further maths.


The kilometre is a relatively recent measure (Post revolution France) -- originally it was defined as: "being one ten millionth of the distance between the North Pole and the Equator measured along the meridian passing through Paris"

Originally Posted by thumbsucker

From my limited understanding imperial uses fractions of 2 and 3 and 4 and 6 and 9 and 12 and 16 and 32 and 64 and 128 and a 1000. Plus probably many more.

The thing that I struggle with is the fractions. The basic math like 1” - 1/4” = 3/4” is easy however something like 3/64” - 7/16” = I would have no bloody clue.

your getting into too much detail.

the beauty of a base 12 system -- think 12 eggs -- is that it can easily be divided into
2 parts -- 6 eggs in each
3 parts -- 4 eggs in each
4 parts -- 3 eggs in each
6 parts -- 2 eggs in each
12 parts -- 1 egg in each

with base 10, you have to stop at 2 or 5 parts -- unless you are serving scrambled eggs


and at the end of the day, all fractions are just marks on a stick -- called a rod by cabinet makers -- which are used to make marks on the work itself.

As it is plainly obvious I have never been to sea. However that does makes sense and I can see the advantage.

As previously stated the quarter system applies to rough cut boards and represents the nominal thickness in quarter inches. My understanding is the that it derives from the saw mill cross feed works when the timber is being cut, the sawyer has a lever that advances the log one quarter inch toward the blade each time it is pulled. The log passes the blade to complete a cut, the sawyer activates the carriage return to bring the carriage back to the initial position on the rails, then pulls the cross feed lever x times to make an x quarter thick board on the next pass, where x tends to be an even number between 4 and the remaining width of the log.

The board looses some thickness drying and still more being machined, so a 4 quarter board generally equates to 3/4 inch or less when faced both sides. The major value of the quarter system for end users is that it distinguishes between rough sawn and finished boards, so there is no need to specify that in material lists etc.

That's what I've read, too, & it makes sense.

When I first went to Nth America I was baffled by the 'quarter' system until the penny dropped, but once I grasped it, it was no bother. I was already familiar with the 'super-foot' (superficial foot,= 1 x 12 x 12"), having grown up in the ancient pre-decimal past, so 'board-foot' was just a name-change. Buying my lumber quickly became an easy enough routine.

The super foot was universally used here, once, & has great merit. It's easy to envisage, particularly when the boards themselves are a standard fraction of a foot, like 6 inches or 9 inches, so it doesn't take too much mental effort to work out your needs from the board widths available. About the only thing I miss with the metric system is the lack of a similar volume measurement. We could use a metric equivalent, if, for example, we adopted a standard 'board litre' (a bleater? , which could be 20 x 200 x 250mm, but for some reason, the concept of a standard volume measurement just didn't come across to the metric world. Pity.

The arguments of base 12 vs. decimal systems goes on & on because there are pros & cons for each - both evolved for perfectly rational reasons. I suggest the decimal system is the oldest counting system, simply because we retained 5 digits & 4 limbs from our fish ancestors. Had we kept 12 fingers instead of 10, we would probably all be counting by 12s, which would make lots of things easier than they are with the base 10 system, as has been pointed out. If you'd grown up counting by 12s, you'd have had two more digits to learn, but manipulating them mentally would be just as easy as manipulating the base 10 system, & you'd find a base 10 system cumbersome, instead.....

The inability of our friends across the Pacific to adapt to a new/old system creates a few problems, most of which can be solved with a hand-held calculator, but one that irks me can't, & that's the practice of manufacturing things like drill bits to Imperial measurements (the U.S. is still the largest market for such things!) and simply re-labelling them to the nearest metric size to flog in our unimportant little country! It's just not close enough, many times!

Cheers,

Hi Ian, one of these days we should discuss counting to 10,000 on your fingers and also doing multiplication using your fingers.

Like you I have also wondered why Australia hasn’t Adopted a “metric board foot”.
Timber is still sold in lengths corresponding to multiples of 300 mm, so a metric board foot would be 300 x 300 x 25

Timber would be sold by the board foot. 1 board foot is a 1inch (4 quarter) board that is one foot wide and one foot long.

Which is what we used to call a 'super foot' back in the day.

Speaking of various units, would any of our American friends like to tell us how long a miner's inch is?

Hi Ian, one of these days we should discuss counting to 10,000 on your fingers

Taught my daughter to do that when she was in infants school - wonder why she went on to be a software engineer.

Over time, I've used degrees, grads and radians depending on the situation. never had a problem with any of them.

Use metric, it's a dozen times easier.

Imperial is not truely a base 12 system.

It just happens that there are 12 inches in a foot.

It's not really any better to have a round number than a decimal. Eg cutting something accurately to 400.0000mm long is no easier than 333.3333mm long. In either case, it's not possible in wood / most materials to achieve that precision.

So 12/3 is no better than 10/3.

Originally Posted by pippin88

Imperial is not truely a base 12 system.

It just happens that there are 12 inches in a foot......

True, pippin; if I implied that, I didn't mean to. I was simply pointing out that certain manipulations are easier to perform mentally in the base system, which is what makes metric systems appealing. If you are old enough to remember pre-decimal currency (which incidentally, had 12 pence to the shilling), you might also remember how some kids struggled to learn it. My MIL was most incensed when they did away with pennies & shillings and claimed she'd never get used to the new rubbish. Within a couple of years, I would ask her to add 1/11, 2/3 and 4/5 pence, and all I'd get is a blank look. but she could tot up a column of dollars & cents real quick....

8/7 pence.

Mick.

Hi,
The Imperial base was 4, 12 inches and pence, 16 pounds 20 shillings.
Regards

What were 16 pounds? 14lbs to a Stone, 16 ounces to a pound (lb).