File talk:Vernier caliper.svg

Wait, if I'm working this out right - just practicing to remind myself how to do this - the measurement on the inches scale and the millimetres scale works out to two different sizes, with enough of a difference not to simply be down to rounding or conversion error and actually to be an artefact of incorrect scaling. Only a very slight inaccuracy, but big enough to matter for something like a vernier.

The inches scale reads 15/16ths, plus 5.5/128ths (or 11/256ths), for a total of 201/256ths, 125.5/128ths, or 0.9805 inches, which converts to 24.90 millimetres using the standard 1 inch = 25.40 mm conversion.

The millimetre scale reads 24, plus 0.75 = 24.75 mm ... which is enough to mean a whole different size of piston ring, for example. (Or, 0.9724 inches ... 124.5/128ths, 249/256ths ... so the error is greater than the ultimate supposed accuracy on either side (which is 1/256th inch or 0.025 millimetre (0.099mm / 0.001", 1/1016" aka "one mil"), if you've got good eyes or a magnifying glass; and still 1/128" or 0.05mm in normal use). IE it's out by 0.15mm or a whole 1/128".

This is roughly equivalent to a conversion factor of 25.2mm to the inch instead of 25.4mm...

Just, y'know, FYI. 87.113.228.199 (talk) 10:10, 18 December 2012 (UTC)