So, you are making a part on a lathe and the drawing shows a hole 0.137" deep. Your tailstock quill only has a ruler engraved in the top, scaled down to the 1/16th of an inch. How do you do it?
Well, Harbor Freight has a 4" digital caliper for $15.00. There must be something doable with that.
Here is the back side of the tailstock. Let's keep things back there, out of the way....
Put the tailstock on the milling machine. Then cut a ledge in the back we can mount to.
Yes, that ledge will work nicely. A few scraps of aluminum, a few screws, and we're there!
Now I know EXACTLY how deep the hole is!!! The original scale is still there- if you need to know 1/16ths!