Hmm, it is soft material, not hardwood. I know I can manually push on the Dewalt (with it off) and make it rotate a little around the middle. I calibrated for size, and all the bearings are making contact, but I kept having my PLA crack on me so I switched to polycarbonate. Is it possible polycarbonate is just too flexible? Dewalt DW660, spindle speed would be approximately 12-32k with a MCLS speed controller (setting of 3 to 10), Inventables sample end mill kit with 1/8 inch 2 flute straight, 1/8 inch ball nose, and 1/8 inch 1 flute upcut (also has some fishtail bits, but being 1/32 in size I really didn’t try to push depth per pass with those). 45% step over, 0.06 inch seems ok, but at .1 inch the Dewalt starts getting slightly pushed out of the way and no longer is cutting in a straight line. Sorry, just noticed I wrote 0.06mm earlier – I meant 0.06 inch.