Pretty new to this but I have been machining Acrylic on converted Sieg X1 mill between 1500 -2000 rpm DOC 1mm FR 1200mm/min 6mm 2 flute and getting good results for welding with Dichloromethane faster RPM than this I was starting to have problems with heat softening the Acrylic as cutting without any cooling. I set it running in Mach 3 and adjusted on the fly for first couple of cuts testing the limits, then went with it. 2 flute performed better than 4 flute for me.