Review on Jasper 400J Model 400 Router Circle Cutting Jig: Precision Tool for Perfect Circular Cuts by Sam Thorpe

Very easy to use. The pins are a very snug fit so can be a bit difficult to release at times, but I'd ease up on this fight against inaccuracies Prefer pens.For those who say cheap plastic has cracked: It's acrylic.Acrylic is very hard but very brittle (ie it won't deform much before suddenly popping) so be careful not to use a gorilla when you tighten it. After making contact, tighten the screws only 1/3 turn." Finally: I have some old Bosch routers that the mounting holes don't match. I inserted the calibration cap into the chuck and then the tool with it placed the calibration disc on the router, then rotated the tool until I lined up one of the mounting holes and screwed it in. Now with two Contact points were secured fairly well, so I marked/drilled/countersunk the remaining mounting holes I needed.