Rear X motor moving before front

I was surfacing my spoil board, and noticed the rear X motor was starting to move before the front one. At first I only thought it was doing it when going left to right, but when I was watching the video I recorded to post here, I can see it doing it when going right to left as well. I’ve been busy, so I haven’t been able to use my MPCNC much. I assume the gantry parts are finally getting more broken in. I planed to rebuild everything to make sure it’s all square again, but wanted to double check and see if there is possibly another issue I should be looking into. I just assume that being out of square it making it torque on the rear motor and pulling it forward when it starts moving.

I tried to embed it, but it’s just showing the iframe code.

Pulley is loose on the motor shaft. You can see the motor shaft spinning inside the pulley when it switches direction.

Go ahead and check all four while you’re at it, maybe some Loctite.


Holy cow! Good eye!