The other day I was cutting rabbetts using a straight bit on the router table. This was for box lids, and I noticed the leading edge of the cut was slightly deeper than the trailing edge, resulting in a slight ridge at the corners. If you looked at the bottom of the lid the low/high ridges would look like this:
L/H------------L/H
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H/L------------H/L
I routed the ends 1st, then the edges to minimize tearout. The ridges are very small, and I just sanded them out. It seems that for any given cut it was slightly deeper at the leading edge. Then I got to wondering what caused them. Any ideas?