Cutting 1/2" acrylic on bandsaw

[adrianpglover]

I'm doing a project right now that involves me making 76 identical L shaped pieces out of 1/2" plexiglass/acrylic, at around 4" x 1" or so. The plexiglass that I have already has the backer paper removed from it as I'm reusing an older piece. When I cut this on the bandsaw, either with a 1/4" or a 1/2" blade the plastic "dust" (for lack of a better term) gets heated up enough that it builds up on the backside of the work piece. I don't have a zero clearance insert, so I can only cut for a short distance before the built up keeps me from moving the work piece anymore, and then I have to back out of the cut with the piece lifted from the table, remove the stuff from behind the piece, then go another short distance and repeat. I'm looking for a solution to this.

One site I found suggested running the bandsaw at 2,300-5,000 FPM, but this suggestion would run my speed range of 798-1736 RPM (divide by 11x3.14159/12). This just seems way too high. I did try cutting in a range of 250-500 rpm, but didn't go beyond that and I still had the plastic buildup. I also read on that same page something about attaching cardboard or craft paper to the back side of the plexi, but I think that's to make it slide smoothly and not to keep the gunk from building up.

Thoughts/suggestions?

[SteveMaryland]

I have had that same problem, with thinner material. 1/2 inch thick would be worse. And 1/2" plate is expensive material so must find a method that works.

Is this material really acrylic, or might it be polycarbonate? Polycarbonate really melts quickly when cut.

I have not found a solution, so I too am interested in a solution. Heat buildup and that sticky plastic melt is the killer.

Maybe direct a cool air stream on the cut, and go slow.

Maybe a "special" blade ($$).

Maybe literally put the piece in the freezer, or put chunks of "dry ice" right at the cut.

Forget trying to use oil or wax to lube the cut, the material will still melt.

[adrianpglover]

The same material that I have with the paper still on it is labeled as "Optix by Plaskolite", which is an acrylic product. On the table saw I use a aluminum cutting blade with a negative rake angle, but it still melts and can build up, even with a zero clearance insert. I haven't used this bandsaw a great deal and haven't had a need for a zci just yet, but maybe this is a case where one could work?

I'm using this material because my work was throwing out a few full sheets of it years ago and I grabbed it up. It was expensive...for them, at least at one point. For me, it's just good material for the purpose.

[edma194]

Get a circular saw blade made for plexiglass and use that for most of your cutting. The carbide teeth will cut faster than a bandsaw and not heat up so quickly. The blade will need time to cool between cuts and may need cleaning if hot plastic builds up on. Unfortunately for L shapes you'll need to finish up with the bandsaw, but you should only need small cuts to release the little cut out piece. Freezing the pieces as suggested above can help.

[JPG]

Slow is the method I have used in the past. The plastic must NOT melt. I have even run 1/4" as an edge finisher through the jointer (again, slow).

1/2" would have to require even slower.

[db5]

I haven't seen this posted so I'll add it. I've cut a lot of plexiglass (?), the easy-melt stuff and use a 7" blade installed backward and run it as slowly as it will go. Takes several passes, raising the table in tiny increments with each pass. It is time consuming but works. My experience is that a non-carbide blade works better.

[adrianpglover]

I ended up getting them all cut out this weekend without much issue. I used a scrap piece of 1/4" plywood as a zci, taped down to the bandsaw table.