Thank you for the replies, gentlemen.
Perhaps my original question was not specific enough though. I was interested in, shall we say the bluing of parts after further sub assemblies are bolted to them.
A specific example would be a lathe saddle is scraped to fit a reground bed. Perfect fit. Then the apron, perhaps a taper turning on the back are bolted on. Has anyone done this and then rechecked the bluing?[/QUOTE
If you've fitted the saddle onto the bed ways correctly you must have also have fitted the saddle keeper strips to the correct running clearance of 0.001" to 0.002".
These keeper strips will maintain the position of the saddle on the ways that you achieved earlier.
If you made a hash of aligning rest of the running gear to the saddle you could encounter other problems. Tight/slack long travel handwheel caused by incorrect mesh of the rack and pinion. Tightness of the saddle at either end of the bed Etc.
Regards Tyrone.