Cutting acrylic

[DickB]

I need to cut 3" and 3-1/2" circles in 3/8" acrylic. I'll use the 3/16" cutting bit. Should I cut full depth, or make multiple passes?

[fwharris]

I would say do multi pass.

[CarverJerry]

is this cast acrylic or extruded? Like with lithopanes they say to use only cast because the extruded will ball up (melt) on the bit and may break your bit. I'd be very careful and stand watching it if you're not sure what you have. Just my 2¢ worth.

[DickB]

It's cast. Curious if anyone has done a cutout like this.

[Mugsowner]

Propane not being hot enough causes you to keep heat on long then you want. MAPP being hotter allows for a faster pass, so you don't that to heat the piece as much.

[Digitalwoodshop]

On Sawmill Creek are a few threads on Flame Polishing. Even 2 that I know of where they did group purchases of Flame Polishers from China. I got in on the first batch. Never used it yet.

[Mike1]

Is there any way to tell if it is cast or extruded acrylic before it goes into the CW? Cutting with my band saw first maybe to see if it balls up? I am having a really difficult time in my area to get cast acrylic. The vendors/glass companies all say it is cast but it all gums up when I use the CW. I tried to etch some letters with a depth of 0.04 and a 60v bit, with no luck.

[Mugsowner]

i have cut 3/16" on a single pass with an 1/8" bit with no problems. Thinking a one pass should work with the big bit. Do you have a spare piece to try and cut just to be sure.

[bergerud]

I have machined quite a lot of thick cast acrylic. I would not even think about a single pass. Use a new bit. (I use two flute short bits.)

[Digitalwoodshop]

I would use a carrier board and 1/4 inch strips of double stick tape to hold the loose circle. I would make a vector path or circle and assign the 1/4 inch bull nose bit. But actually use the 3/16 cutting bit.

My thinking is that this would lock the feed rate into 1st or it's slowest gear giving you a smoother cut. Not use Cut Path and Tabs. Because remember the machine is going to think you are cutting wood and will likely shift into the faster cutting rate destroying something...

LHR... What are your thoughts...?