Originally Posted by
mountaindew
Could be a compounding machining error. Tool heights, tool flex, tool runout, non flat / square/ parallel machining surfaces before and after operations and flipping sides all compound any little error/problem. When you get to the final whisper cuts on the last side to finish you can see something is off.
If you made this in the past and now your getting different results maybe problem is cutting tools size, flex, overhang, runout has changed. I see this a lot when I speed things up.