A plastic cutting router bit is a bit designed specifically for cutting acrylic, polycarbonate, PVC, HDPE, and similar plastics without melting, chipping, or leaving a gummy edge. Plastics behave very differently from wood, so a standard wood bit often fails on them. A single flute design is most common. One large flute gives plenty of room to clear chips quickly, which keeps heat down. Some are two-flute, but single flute is the classic choice for plastic. The main enemy with plastic is heat. If chips aren’t carried away fast, they melt and fuse back onto the bit and into the cut, leaving a rough, cloudy edge or even gumming up the bit. A bit with big flutes and a sharp edge removes material in clean chips, which carry heat out with them. Often upcut, sometimes downcut or compression. Upcut clears chips best and is the usual pick for plastic, but a downcut or compression bit can give a cleaner top edge on sheet stock. Canadian Woodworker stock several different options from CMT and Royce-Ayr.