Is it possible to discern whether a measurement difference between ends of an alignment bar is due to tailstock misalignment or bed twist?
I guess the first thing is to get the tailstock alignment correct with the tailstock right at at the headstock.
When I got my lathe back about 1968 it had very little bed wear and I have not put too many miles on it.
In practice I have never paid much attention to twist because I do not generally work with long stock. Years ago I borrowed a precision level from work and leveled the bed. I moved in 1985 and since the bed had an adjustable tail end base I just loosened the set screws to let it settle out and then snugged them again, tightening each a little at a time, back and forth. It is on a heavy steel cabinet.
I looked at the Edge Technology web site. Much of their product line is affordable for a hobby situation.
From: Steven H
Date: Thu, 13 Jun 2019 23:09:02 EDT
What you are describing - an alignment bar placed between centers - is one way of checking and setting the tailstock alignment both horizontally and vertically. These alignment bars are commercially available - Edge Technology makes one that is 12??? long. Don???t know if such an item could be used to check for lathe bed twist, but if the idea would work, the bar should be max length the lathe can hold between centers.