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What is a thou?
One thou is one thousandth of an inch: 0.001 in. It is machinist shorthand for talking about tiny movements and tolerances without reciting a pile of zeros. Odd sixteenths land between two whole thou, so this trainer accepts either nearest reading.
What is a tenth? In machining, one tenth means one ten-thousandth of an inch: 0.0001 in. It is one-tenth of one thou, so 10 tenths equal 1 thou.
How small is that?
Kitchen foil: about 0.5–1 thou
Human hair: about 2–5 thou across
Printer paper: about 4 thou thick
Thousandths Trainer
Difficulty Apprentice
0.025 in steps plus practical sixteenths, rounded to the nearest thousandth.
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Eight-question expert test
Seven Expert ruler targets, followed by one bonus question. The selector readout stays locked for the entire test.
Question 1 of 8 · Expert
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