by maintenanceguy » 2 Feb 2008 6:55
micrometers are typically used to measure to the ten thousandths of an inch. Calipers only to the thousandth.
Keys don't need to be cut to the nearest ten thousandth and all the available key machines probably aren't built to close enough tolerances to cut that accurately.
But, the advantage of micrometers is that they're a very convenient size and shape to fit right in your hand while measuring key cuts. Calipers are usually bigger and a little awkward when measuring small things.
Whatever you get, I'd really recommend a digital display. Vernier scales hurt my eyes and there's a possibility of reading them wrong or doing a math error.
I avoid harbor freight tools because they mostly sell junk but since you only need accuracy to the thousandth, WOT's idea would probably work for you.
-Ryan
Maintenanceguy