Direct measurement is my choice. i.e. set up blocks for routers, story sticks for case work, duplicates for setting saw fences or length stops, drafting triangles, engineer's squares...etc. I try not to use measuring devices such as tapes, micrometers, calipers, as much as possible.
Now, in setting up machines to spec for accuracy and safety, I use the devices mentioned above, and more, quite often.
'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton
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