As the title says really, I can work with many different measurements (full inches, feet, yards, metres, mm etc ) but I’ve always struggle when it comes to imperial measurements of fractions of an inch. Why did people use this measurement because to me it seems a crazy way to measure something!
In: Engineering
Wait till you get a measurement like 5inches + 63/64ths of an inch which was on blueprints i have used.
Inch doesn’t have any proper subunits and unlike the SI/metric system, the American/Imperial system of units doesn’t have any build in ways to create subunits.
A sent anything better the traditional method is to subdivide the inch into fractions based on powers of two: halves, quarters, fourths, eights etc.
These have the advantage of being easy to construct geometrically, even if they are more cumbersome to do math with than metric based powers of ten. They also don’t lend themselves to going too small as nobody measures things in 1024th of an inch and are completely divorced from any sort of volume measurements, but for measuring length of human sized objects it is a system that is good enough.
I’ve never seen anything measured in fractions of an inch if its smaller than an inch I’ve always seen centimetres or mm used.
Because sometimes you need to measure the length of something that isn’t exactly a multiple of some number of inches.
A centimeter is just 1/100th of a meter. 38 centimeters is 38 hundredths of a meter.
In the Imperial system the inch is the smallest common unit of length, so anything smaller than that is a fraction of an inch.
Simple fractions like quarters or eighths of an inch are most common, but you’ll see people doing fine work in hundredths too.
Quarters and eights became so common because they’re just divisions of 2. You can eyeball them with decent accuracy.
It’s crazy to divide things by 2? Base 2 is pretty easy to deal with. We divide things in half way more than we divide things by 3/10s. A half inch is half of an inch, 1/16th of an inch is half of 1/8th. It’s all just dividing by 2.
Because that’s what we have? There is, to my knowledge, not a proper imperial unit smaller than an inch, or at least not one that gets used regularly.
Rulers are broken up into sections as small as eighths generally. However again, I have no idea why we still use that system, but for a wide chunk of the population, that is just what is available. I’m sure there is a more concrete/historic reason for it.
Uhm… Milimeters are also fraction of a meter, just with a more ordered concept how to divide the unit.
Imperial units predate this structured approach, so they are divided simply as people see fit.
> Why did (and why do) people use measurements in fractions of an inch?
Because it’s REALLY easy to divide something in half with simple tools, but it’s hard to divide things by 10.
This is not much an issue now, but it was very helpful in older measuring systems (in fact you see divisions like this going all the way back to the ancient Egyptians).
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