Official Luthiers Forum!

I have these tonepros locking studs to install in a guitar. I used the recommended drill bit on the holes (11mm) and the un-knurled part of the shaft fits perfect, but the knurled part will be super tight. I'm unsure about how much pressure is needed, and how to apply that pressure. Also should I install before or after finishing the body of the guitar?

Depending on the type of finish used they could be installed either before or after finishing. An oil type finish might allow them to be installed after finishing, but for a "film" type finish (lacquer, varnish) where pressure against the finish might mar it or cause it to lift installing prior to finishing might be better.
The Knurling is supposed to hold the stud into the wood and should go in tight. I usually press them in with a "C" clamp or an"F" body clamp. In a particularly hard wood or a wood which may split it is sometimes safer to drill slightly oversize and epoxy them in place - use your best judgement.

I press them in with the quill of my drill press (I know it isn't designed for it but I don't own an arbor press (yet)). Chuck a piece of dowel in the drill, pad the table and gently press them in. I would use some other sort of clamp but I don't have anything deep enough.

All of my guitars have had lacquer finish and I drill the holes before finishing but install the studs afterwards. I clean out the entry edge of the hole with a counter sink (or sand paper) and lightly chamfer it and so far the finish hasn't chipped at that spot.

Don't forget to run your string ground wire to one of the studs. I just fan it out and put it in a hole that goes into the side of the stud hole.

"I press them in with the quill of my drill press"

That might even work better than the clamp method if you have a drill press - I'll have to give that a try next time!

I also press tuner bushing in with the drill press. Slow, gentle and in line

Ideally I would take a piece of dowel and turn it down so the center fits inside the hole in the stud or the tuner bushing and then has a wider shoulder to actually do the pressing. I keeps saying I'm going to do that but for two or four or six studs....