Cutting rabbet on plexiglass

[Jim Barstow]

I’ve got some 1/i8” plexiglass that I need to fit into a slot that is slightly undersized and I can’t modify the slot. I figured the easiest way to fix the problem is to cut a rabbet on the plexiglass. The rabbet won’t be very big, 1/2” by less than 1/64” deep. I’m very wary of cutting plexiglass, however, due to some very bad results caused by crappy tools and ignorance.

Any advice on how to do this without destroying the plexiglass or myself would be appreciated.

[johnny means]

It machines easily with normal tooling. Aggressively hooked tooling can cause chipping. I would probably opt for a router with a fence. Like any other thin material work piece support or hold downs will need important.

[Mike Wilkins]

Any way to just sand a little off the edge to fit the intended slot? Sometimes done to fit a plywood panel into a slot for frame and panel building.

[Carroll Courtney]

Like the ideal of router table but maybe go with the rotation of the bit to help prevent chipping,no more than what is needed to be remove shouldn't be problem. But maybe a test piece would be worth trying

[Frederick Skelly]

I wonder if a sharp block plane would do this? I've used one to smooth a plexiglass edge after sawing a panel to size. And I know you can cut a shallow-angle (camfer) on a plexiglass edge.

[John K Jordan]

I’ve got some 1/i8” plexiglass that I need to fit into a slot that is slightly undersized and I can’t modify the slot. I figured the easiest way to fix the problem is to cut a rabbet on the plexiglass. The rabbet won’t be very big, 1/2” by less than 1/64” deep. I’m very wary of cutting plexiglass, however, due to some very bad results caused by crappy tools and ignorance.

Any advice on how to do this without destroying the plexiglass or myself would be appreciated.

I met a guy who's company built and installed displays and shelving in retail stores. He said he machined a LOT of plexiglass. He gave me a pile of carbide router bits that were used only once but still had plenty of use left in them. I believe he said these were specially designed for plastic. I don't know where to get them but a quick google search gave plenty of links.

JKJ

[andy bessette]

Carbide router bit in hand-held router against straightedge guide.

[Richard Coers]

A single O flute router bit is the best, but the 1/8" plexi will need some kind of backer if you use a router table. It will like machining a noodle otherwise. A hand plane will work on polycarbonate, but not on acrylic.