[Shop-talk] Micrometers

[Nolan]

Not sure what you mean by inside and outside teeth.  There is a rack and a 
gear.  The gear spins as it goes up and down the rack.  No, there is no 
adjustment.  Nor is there and ajustment on manual ones.  The ratio is fixed. 
Both the manual and electronic ones let you adjust zero to your hearts 
content.

The most effective way I've found to check the quality of a caliper is to 
close the jaws, zero the display, open and close the jaws, and see if it is 
still zeroed.  Don't know of any way to ensure a caliper os good and 
undamaged by mail order.