Bad scratch and terrible results

[dandangerous (Dan Dornback)]

@Bonhoeffer

Look at this slip – it is huge. Made a terrible sound as the #201 bit cut full length into the mdf. Only 3/4 inch thick but still, I feel totally non confident in the shapeoko staying to the actual cut and want to find out what is causing this.

Looking at the size of the thread marks crushed into your rail - looks like a set screw. Have you checked the set screws on the pulleys?

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…

This could cause errant cuts as well if you are missing a screw and pulley is slipping.