How to read a micrometer

[not done it yetParticipant @notdoneityet]

Bill and NDIY make a good point about needing to account for temperature when taking high-accuracy measurements, but it's just one of several factors that reduce the accuracy of very fine measurements.

Dave,

My post was to reinforce that the OP could help himself by making careful measurements on items with slightly different dimensions, to determine how to read his particular instrument. Nothing particularly about absolute accuracy.

[SillyOldDufferModerator @sillyoldduffer]

Posted by not done it yet on 23/11/2021 13:26:19:

Bill and NDIY make a good point about needing to account for temperature when taking high-accuracy measurements, but it's just one of several factors that reduce the accuracy of very fine measurements.

Dave,

My post was to reinforce that the OP could help himself by making careful measurements on items with slightly different dimensions, to determine how to read his particular instrument. Nothing particularly about absolute accuracy.

Understood ta. I hijacked your 'just measure and record all digits, then warm the item by a few degrees and record the new digits.'

We're both saying temperature alters dimensions, except I went a step further by pointing out accuracy requires temperature to be taken into account. I think I'm correct in saying modern micrometers are calibrated at 20°C whereas older ones were done at 64°F, causing a tiny error. Measuring tenths in an unheated workshop without recording the temperature is dubious.

I'm concerned new boys might waste money buying tenths micrometers due to misunderstanding what they're for. However, far worse things happen in my workshop!

Dave

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