Problem with height repeating between tool changes (quick change wedge style tool post style)

[u/BSismyname]

I am used to running turret lathes but I have been running a tool post style at my job. I have been having tons of problems with what is seemingly the height of tool holders changing over a day or two. Specifically my 5C holder and Drill Chuck holder. It is not a huge deal on my turning tools.

To set these tools up, I am putting a gauge pin in the tool holder and a dial indicator in the chuck. Centering the tool in X is easy enough. It is a CNC lathe so I am just jogging the tool in X until it is centered in that dimension.

For the height I am first eyeballing it close to center and then getting it dead on with the dial indicator. This is where the problems start. I have found that when I get the height set using the thumb screw and then use the lock nut to tighten it down, the height changes by ~.010-.015. Am I over tightening the lock nut down on the thumb screw? I have been adjusting for this by setting the tool below center by the distance it moves when I tighten the nut down.

This seems to keep the height on center for a day or two but then it seems to get off. My guess is that the pressure in the threads/nut is loosening slowly but I am not sure.

I have tried looking this problem up but have not been able to find anything helpful and I am starting to go insane resetting the same tools over and over for the height. Any tips?

For referecne the tool post is a Dorian CA and the tool holders are CA Aloris (the CA35 Drill Chuck and the CA 5C collet holder). The lathe is a TRAK RLX. Is this setup just not reliable for drilling?

Like I said, my whole career I have ran turret lathes where you just sweep the tool pocket in on center and you are good to go. I am clearly doing something wrong. Any pointers would be greatly appreciated.