Z axis inconsistency, or maybe it's Y?

Simple question, at least I hope it is. Can anyone explain what error I am seeing here and if there is a solution? It takes 5 passes to go through 3/4 in material at .2 in per pass. The first two cuts look ok by cut 3 something is awry and by cut 5 my material is several millimeters short on the lower edge and has this lovely stair step on the top that needs to be sanded off… Any thoughts on what’s going on here and how to correct? I’m at a loss. Thanks!


How deep of a depth per pass are you using? This looks to me like it could be a dull bit or a little bit too aggressive of a cut depth. If you are using a sharp router bit I would recommend a maximum cut depth per pass of 1/2 the bit size so for a 1/4 inch router bit that would be .125 inches per pass.

is your sled lifting when it cuts? It could be a chain alignment issue.