Yes, acrylic IS flammable.

[Joe Pelonio]

I hope I don't have to use this supplier again, because the 12x24 sheets I got from them are not cut nearly square. They are a good 1/4" off so won't lie flat on the vector grid.

So, I'm running a job first that cuts a straight line top to bottom
on the left edge.

This last piece ws more like 3/8" off. I'm glad I was watching when it ran because when it got to the bottom where the wasted edge tapered off,
and it got really thin, the acrylic just started burning, flames 1" high even with air assist on. Had to open up and blow it out.

May have to use a saw instead.

[Lee DeRaud]

Clear or tinted? Cast or extruded? Bare or masked?

Reason I asked, I just cut some clear extruded and was getting a lot of flareup with the factory masking. Took that off and put on transfer paper: less flareup but still some. As you say, it was worse at sharp corners, probably something to do with air being available to it from multiple directions.

So I tried it bare...huh. No flame, no smoke, the only time I could even see the beam was when it hit the edge of the honeycomb underneath. I'm beginning to rethink my method for working with this stuff.

[Joe Pelonio]

Lee,

This was bare on top and had the factory paper underneath. I could see that the acrylic sliver tip itself was burning, not just paper flareup. I rarely
have flareup issues and for this production job cut with transfer tape on to, factory paper on the bottom. It was cast 1/4" flourescent orange. I have noticed more flareup for some reason with cast black 1/4", in fact I increase the air to 40lbs for it and normally use 25. Never had an issue with clear, but almost always use cast in 1/4", sometimes extruded for 1/8".

As you suggested this time it was probably the air available to all four sides.

[Mike Null]

Joe:
What about increasing the speed and running it in two passes?

[John Barton]

When I cut my acrylic jigs I usually run two to three passes to prevent the flame and excessive melting instead of trying to cut it in one pass. Of course this affects the size by a few thousandths but for my jigs it's okay.

[Joe Pelonio]

When I cut my acrylic jigs I usually run two to three passes to prevent the flame and excessive melting instead of trying to cut it in one pass. Of course this affects the size by a few thousandths but for my jigs it's okay.
It's only that close to the edge where I've had the problem and if I have to do it again will try your suggeston.