With a good digital caliper, running nice smooth sweep from open to close will show it is working correctly. If it repeatedly returns to Zero it will be good. You can buy 1" and 2" standards if you are worried about it.
My Mitutoyo Digital Calipers are about 30 years old and have been awesome! I paid a small fortune for them at the time.
There is a set of Brown and Sharps on Craigslist for $45
http://oklahomacity.craigslist.org/tls/5110281022.html
My Mitutoyo Digital Calipers are about 30 years old and have been awesome! I paid a small fortune for them at the time.
There is a set of Brown and Sharps on Craigslist for $45
http://oklahomacity.craigslist.org/tls/5110281022.html