There was a project that i did once where i was making a matched set of 6 candle holders that had to be exactly the same. The problem was, i couldn’t seem to get all of the candle sticks the right width. They were always too small, because i would use the calipers to check the width and it would be too wide, so then i would sand it down more, but it always ended up a little smaller. I FOUND A SOLUTION!:) if you have some old calipers, lightly sharpen the calper tips so that the act as scrapers to scrap the spindle down to the exact width.
p.s. sorry that the writing is a bit hard to understand