[SOLVED] Z axis skipping threads?

So I noticed something weird when I was doing some routine cleaning on the x carve. Heres a video of it:

This only really happens when plunging and it seems to happen at random heights. Any ideas what could be causing this? I cut aluminum almost exclusively.

Edit: I’m running the Acme Z-Axis

Do you not have the nut under the bearing?

I have the acme rod, it didn’t come with a nut.

First your pulley is not inserted all the way down before tighten the set screws. Second, your V Wheels are not adjusted properly, that’s possibly the reason for jumping Z.

Good call on the set screws. Looks like they came loose a bit and my top nut want screwed exactly all the way down so there was a bit of play.