Cutting and routing plexiglass

[fritz eng]

making a base plate for a router with cast acrylic plexiglass for mortising. Can I use a dado blade or carbide router bit to cut a 1/4" slot for bolts?
what number tooth 10" saw blade is recommended for general cutting acrylic?? i understand generated heat can be a problem.

[Jacob Reverb]

FWIW, I've found that it really, really, really wants to lift away from the blade (with presumably unhappy outcomes after that), so I usually cut it on bandsaw now.

[fritz eng]

Jacob

What tooth bandsaw blade did you use?

[Frank Pratt]

FWIW, I've found that it really, really, really wants to lift away from the blade (with presumably unhappy outcomes after that), so I usually cut it on bandsaw now.

Yes, I agree. I think it's because the acrylic tends to get soft & grippy on the edges from the heat. You do not want to use a push stick, but rather some kind of push block that will hold the sheet firmly down. I've used a plywood blade, but there's probably a better choice if you're going to do lots of cutting. You need to feed fast enough to keep it from melting but slow enough that you don't get chipping. Haven't tried routing acrylic.

[Lee Schierer]

As others have said you need to hold it down against the table. If it starts to chatter bad things happen quickly. For what you are making Lexan (polycarbonate) would be far better and less likely to chip or crack under your screw heads. As a bonus to using Lexan, it machines much cleaner than acrylic and you can even run pieces across your jointer.

[Frank Pratt]

As others have said you need to hold it down against the table. If it starts to chatter bad things happen quickly. For what you are making Lexan (polycarbonate) would be far better and less likely to chip or crack under your screw heads. As a bonus to using Lexan, it machines much cleaner than acrylic and you can even run pieces across your jointer.

Agreed. The major downside to polycarbonate is that it is a lot more sensitive to UV, so exterior use will cause it to yellow. But for a router base, that isn't a concern. It's also lots tougher than acrylic.

[johnny means]

Lots of negatively hooked teeth work best. Blade up high will avoid lifting. Lube is your friend, as the melted plastic wants to gum up the blade. Take your time, let the blade do it's thing.

[David Buchhauser]

making a base plate for a router with cast acrylic plexiglass for mortising. Can I use a dado blade or carbide router bit to cut a 1/4" slot for bolts?
what number tooth 10" saw blade is recommended for general cutting acrylic?? i understand generated heat can be a problem.

Hi Fritz,
I have not cut acrylic yet on my saws or cnc router, but I have seen it done in videos. There is a SMC member (friend of the creek) Gary Campbell who I would expect is an expert with this type of material. You might contact him for some ideas.
David

https://sawmillcreek.org/member.php?55049-Gary-Campbell

[John Stankus]

What I found helped a little (I won’t claim to know what will completely consistently work). Is to sandwich the plastic between some 1/4 inch plywood or other wood to support it well.

[Bernie May]

Will cutting it on sacrificial plywood with a tracksaw work?

[Grant Wilkinson]

@Fritz: Are the slots you want to cut stopped slots? If so, I would use a 1/4" router bit on the slowest speed you can set your router. I do quite a bit of this for jigs, using corian, which is really just a fancy plastic. Slow and steady seems to work.