Why is my 1st pass out of alignment?

Hi folks,

Having an issue where my first pass is about 1mm off in the x axis, but successive passes come out as expected. I’ve seen it in both positive and negative directions on the x axis.

I’m using a .125" square end mill on a Shapeoko 3. I’m cutting 1/4" baltic birch plywood that I’ve secured with double sided tape.

Here’s a screen shot of my settings. I’m using default Carbide Create values.

Any suggestions on how to correct this?

@thinkkeyspeak
Check your pulley set screws.
Check the belt tension.

Please use the checklist:

http://docs.carbide3d.com/article/41-machine-operating-checklist