X Y shifting occurring on a contour cut but it fixes itself after the first layer

[dandangerous (Dan Dornback)]

@Primatechallenge this was a follow up to my original post you mentioned:

Pulley set screws - XXL

After dealing with the Y1 pulley set screws backing out numerous times on my XXL and messing up jobs, finally decided to implement regular socket head screws - covered here and other places, but a couple points to add for others with the same problem. The socket head screw size you need is M3 x 8mm, you can get a multi-size box from Amazon for $6 that will be more than enough. You want to use “purple” thread locker, it’s low strength and made for set screws. Several brands out there for ab…

Even though I thought the set screws were tight, they just weren’t grabbing enough and slipping causing erratic cuts just like yours. Switching set screws to the ones I show in the post solved all my issues.

Also had this happen with a bad belt. The belts that came with the machine were the wire reinforced and the wires inside stretched and broke, but the belt looked fine. That little area caused a gear skip and showed very similar symptoms to this. (I switched to kevlar belts and like them much better).