How deep ? It’s turtles all the way down!
Anyway, how do you like those ballscrews ?
If you were so inclined would you mind cutting a disc, any size, in acrylic or aluminium, and post a close-up of the wall finish in that thread ? I would be interested to see if the extra resolution you get with those ballscrews is showing (in other words, I’m looking for an excuse to upgrade too)