I am having a problem with the router bit frequently slipping on my CNC router (Sabre 408) and I'm wondering if anyone else has experienced a similar problem. This is a recent occurrence since I’ve returned from a vacation and another operator was using the machine, so I know it’s not an issue of how much I’m tightening the nut on the spindle. It has a brand new collet, so I’ve ruled that out for now. I figure it has something to do with the nut or the spindle, possibly the threads being damaged. I’ve cleaned out both threads with a brass brush and acetone, so there’s no more residue on either. I’m trying to avoid the “just tighten it like the hulk” scenario since I’ve heard that’s a really great way to damage the threads. Wondering if anyone has experienced anything like this before, if I’m right in my thought that it’s the threads, or if I’m out of my mind and it’s all in my head. I would really appreciate any help with this situation.

Also, as a side note, I have never in my life posted to a forum, so if I'm "you're doing it wrong Grandpa" or this is not the place for this post, my apologies.