How to cut acrylic?

[sdk1000000]

It sounds like a bandsaw might be a better choice than a table saw for acrylic. Wouldn't there be less mess, less melt and more flexability in making the cuts?

[smorris]

I just ran a sheet on acrylic through my 3100 today. You just have to show some alacrity when you run it through, no pauses, I fed it about a 1/2 foot a second for 1/8" stock. I was using the standard BT blade and it worked fine for what I needed.

[Stytooner]

A bandsaw and the BT are great for cutting plastics, but not for getting a circle cut in the center.

[axa]

I made a kickass router plate out of acrylic by cutting the hole with a nice quality adjustable hole saw.
Not a regular hole saw, but the adjustable, with a bit that much resembles a metal lathe bit.

Make sure the cutting tool is sharp, it worked so well i was able to cut a small thin lip for router throat plates with it.

Looks like it was cnc machined.

[LCHIEN]

I made a kickass router plate out of acrylic by cutting the hole with a nice quality adjustable hole saw.
Not a regular hole saw, but the adjustable, with a bit that much resembles a metal lathe bit.

Make sure the cutting tool is sharp, it worked so well i was able to cut a small thin lip for router throat plates with it.

Looks like it was cnc machined.

that would be what they call a beam cutter.
Has a drill bit in the center and a square horizontal beam with an adjustable radius where the cutter is mounted.

[LinuxRandal]

Absolutely. A dremel would work perfectly if it was attached to a cnc machine.

A hole saw, jig saw, scroll saw etc... will all tend to melt it and close the cut behind it. Cheap hole saw will bind. The right blade in a jigsaw will work to get it close and then sand or use a router and template.
I would use a router and template if I didn't have a cnc machine.

It will do fine. Spiral flutes are probably best (there are companies that specialize in cutters for plastics), but a regular straight bit will do for a one-off like this.

A Dremel can use spiral type bits, like the Rotozip style. They should leave an opening that is wider then a jigsaw blade (less likely to melt and close up on you). Moving them up and down will help to clear the shavings.

For the router table, you could also drill a series of holes, then just cut between them (or drill all around), then clean it up with your router. (and when your done center it to determine where to drill for the mounting screws).

I do disagree that you can't get good support without a tablesaw to cut the plastic. Your base is independent of your guide system (in most cases). One friend recommended to me once before (I found a piece of scrap the size I needed), that I run my circular saw backwards, with the blade lowered about 1/32" to score the plastic, before going forward. (I was going to cut it on some scrap plywood)

The last time I cut thicker plastic (more then 15 years ago), I believe I used a Beaver bit (sold as a multipurpose drywall/wood drill bit), in a router, then cleaned it up to final size.

[movnup]

I've been cutting a lot of it lately as I have made five zero clearance inserts so far for my new router table insert for the BT3, dust collector for the back of the router fence, as well as the access door insert underneath the table top. The lessons I picked up from the plastic shop where I bought a bunch of 12 x 12 cutoffs as well as trying out a few things are as follows:

1) They use a 70 tooth 10 inch blade (Freud) on the table saw that is made for plastic with a fairly agressive feed rate. I used my Forrest on the BT3 for the larger cuts and it worked fine but I have a springboard pushing it into the fence as well as two featherboards pushing down - medium fast feed rate. They just pushed it right through without any issues.
2) Up to an 8 inches I used a 80 tooth blade on my Dewalt CMS with no hesitation and a fair amount of force on the downstroke.
3) For holes I went to the highest speed pulleys in my drill press and used carbide bits that worked great. For the large circular cutouts I used different sized hole saws with a backer board and had no melting or burning problems. Once again a fairly agressive feed rate.
4) I tried blades made for plastic in my Bosch jog saw and felt that I didn't have nearly the same level of control. That could be just me though as I never worked with plastics much before.

A neat trick they taught me was to sand the edges with 80 grit and then use a small butane torch to heat the edges. They begin to melt and then turn the edges (or any other surface imperfection) crystal clear without a mark on them. It's almost like magic watching it change from rough to perfectly smooth and clear but practice on your cutoffs first. Once you get the feel for how quickly it melts (before it bubbles up) it's super easy.