Not all material being removed

What can cause this problem? Most of the letters I’m cutting have a ring around them where the material was not all cut out. This happens with both inside and outside cuts. It’s almost like when the tool makes the finishing cut, the rough cut wasn’t big enough. I’m using a 1/8 inch end mill, and the settings are 10mm feed rate, .75 mm depth of cut, and 45% stepover.

See the picture for an example.

Thanks for any help!


Definitely go deeper per pass, 45% is good for the roughing, try less than 10% for the finishing pass and have it go the other direction or waterline, and have the finishing pass depth less than half the roughing.

Thanks so much for the tips, Ryan. Are those all things I can set in ESTLCAM (different step over, depth, and direction for roughing and finish passes)?