Yesterday I decided to get out and replace a hatch port on a dinghy I have listed for sale. It came with just the ring. The screw in center disc was missing. The new port was about a 1/4" larger than the OEM ring. No problem, I have a Roto-Zip... The Zip came with a circle cutter that I've never had the chance to use, but it looked simple enough. The plan of attack was to cut a hole in a piece of plywood and then use it as a guide along with a veining bit to enlarge the hole in the dinghy. Well... let me tell you... that thing sucks. I started with a piece of ply about 4' long, and ended up screwing up the entire piece. But.... I did end up with 5 side stand discs... And I bet you thought this thread wasn't going to be motorcycle related....