I wish cutting acrylic was an exact science, but I don't think it is. Had recent success with 3/32 bit in a pocketing application, rpm was 14k, feed 50IPM. I was happy with the results. Your melt (weldback) can be manipulated by cutting in opposite direction. When you get the melt, I usually see it as an indication to lower rpm's and speed up the feed rate. When ideal combination is reached chips become powder-like. Been cuttin acrylic 7 years.....still learnin! Hang in there! Learnin aint so bad.