From everything I’ve heard it’s a hodge podge, since the US, with the worst system, is the only one to use it consistently. Building plans would reference it by cm however.
What I was more referring to was from the perspective of the carpenter doing the work.
Fractions or decimals aren’t specific to us customary or metric. You see decimal inches perfectly often, or at least I do.
Fractions are a more convenient way of dealing with multiplying or dividing numbers without a lot of mental effort. 1/3 of .125 is gonna take a second to figure out. 1/3 of 1/8 is 1/24. 5 1/8 units is just ”5/8”, rather than the .625 in decimal.
It’s definitely less effective for numerical sorting in your head, but if I’m sorting screws or something, I’m probably gonna just look at them rather than compare the labels.
I understand the underlying principle, but I’m not sure if it actually shakes out that way for a few reasons:
If you asked a carpenter to cut something to 1/24", they’d be like “what?”. Sure, the math was easier, but the result is unusable. No measuring instrument has divisions of 24ths. The person making a cut would need it in terms of 8ths, 16ths, etc. Any time saved at the initial stage is lost when they need to convert it again to a useable denominator.
Secondly, what’s 3/32nds of 17/128ths?
The examples you give are harder in decimal form because nobody is going to make metric carpentry designs for things that are to the tenth of a millimeter, so 1.25cm isn’t even real.
I admit, there are a lot of specific scenarios where fractional convention is helpful. I just personally think they don’t outweigh the drawbacks.
I looked it up and they use 2/5 meter spacing. Some other countries nearby use 3/5th though.
And it’s described locally as 2/5 and 3/5, rather than 40 or 60 cm?
If so, I’m shocked, but delighted to have learned something unexpected
From everything I’ve heard it’s a hodge podge, since the US, with the worst system, is the only one to use it consistently. Building plans would reference it by cm however.
What I was more referring to was from the perspective of the carpenter doing the work.
Fractions or decimals aren’t specific to us customary or metric. You see decimal inches perfectly often, or at least I do.
Fractions are a more convenient way of dealing with multiplying or dividing numbers without a lot of mental effort. 1/3 of .125 is gonna take a second to figure out. 1/3 of 1/8 is 1/24. 5 1/8 units is just ”5/8”, rather than the .625 in decimal.
It’s definitely less effective for numerical sorting in your head, but if I’m sorting screws or something, I’m probably gonna just look at them rather than compare the labels.
I understand the underlying principle, but I’m not sure if it actually shakes out that way for a few reasons:
If you asked a carpenter to cut something to 1/24", they’d be like “what?”. Sure, the math was easier, but the result is unusable. No measuring instrument has divisions of 24ths. The person making a cut would need it in terms of 8ths, 16ths, etc. Any time saved at the initial stage is lost when they need to convert it again to a useable denominator.
Secondly, what’s 3/32nds of 17/128ths?
The examples you give are harder in decimal form because nobody is going to make metric carpentry designs for things that are to the tenth of a millimeter, so 1.25cm isn’t even real.
I admit, there are a lot of specific scenarios where fractional convention is helpful. I just personally think they don’t outweigh the drawbacks.