I received a drawing a few months ago that had the following dimensions called out: 1/8", 2/8", 3/8", and 1/2". This one hits a little too close to home.
The measurements in parentheses are millimeters (or close enough), so it looks like a shitty conversion from a non-US manufacturer that doesn’t use imperial.
36" is 914.4mm, so that’s what I’m basing this off of.
Yeah, I reckon somebody told the drafter Americans use inches and fractions and they did not clarify any more than that.
Our system is antiquated and kind of unwieldy, but it is a system. Power of two denominators for most things, which comes from a practice of just dividing shit in half, and decimal inches for surveyors and machinists.
In the US trades, every measurement is expressed in ft/in, with fractions by 1/2, 1/4, 1/8, 1/16, 1/32 as they’re expressed on a standard US tape measure. No one uses 5ths, 10ths, 3rds, etc.
When dealing with fractions of an inch, measuring devices ALWAYS use base 2 denominators (1/2 inches, 1/4 inches, 1/8 inches, 1/16 inches). They actually have ticks on the tape measure to represent those values. By convention, measurements are as well written down using that same principle.
It’s so ubiquitous, that people fall apart if it’s deviated from.
Also, from a practical perspective, there won’t be an explicit mark on a tape measure for any of those measurements, so they’d need to kinda fudge that if they wanted to take a more precise measurement with a standard tape measure.
In Canada at least, it’s pretty common for a tape measure to have metric and imperial units. Not sure if that’s the same on the US. In this situation, I’d just use the metric. And for any of the highlighted measurements, I don’t think I’d be to stressed out about if I mismeasured by a 16th of an inch anyways.
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