1st cut in a pocket is too deep

So puzzling little thing. I’m doing cabinet doors for my kitchen and cutting square pockets on them. Every door, the very 1st line in the pocket is a tiny bit deeper, leaving a bit wide groove. The following 10 billion lines, totally fine and level, but I’m stuck filling that little groove before I prime.

I’m cutting mdf, .25 end mill, and a very sedate cut speed.

And right now as I type this out, I’m thinking it’s because it’s a up cut bit and the 1st cut has material on both sides so it’s pulling the bit down on the 1st line, and the remainder there is only material on 1 side so it’s not doing that. And I could probably fix this by cutting a tiny bit shallower and doing a final pass. Or by switching to a compression bit.

I’m right aren’t I.

1 Like

As I was reading the first part of your post this is the exact thought I had. Best way to find out is make your DOC .5-1mm shallower than your final depth. Will make the cut take longer but should leave a nice clean bottom if that is the actual cause. Makes sense anyways LOL

Pic might help, not visualizing.