Cutting 3/8 inch Acrylic

I’ve been trying to get the chatter off the bottom of even 1/8”. I found I need to put on a riser with open space under it so I didn’t get the flash back on the bottom from the tray. I tried it on top of a piece of draft board but at that thickness I still got pitting. But that might work for a multi pass cut on something this thick.

Hee hee. The board is by a guy called Mitch Feig. I built the clock with IN-8-2 tubes that I colored red (Pebeo Vitrail Paint). I have far too many nixie clocks to be honest…:slight_smile: If you want more details then PM me.

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Oooh…that’s a good idea. I will try that. I presume you just change the focus height by the distance propped up from the crumb tray…

I just worked with 3/8" opaque blue and a clear, and started with PG for thick blue, setting for actual height, but ended up speeding it up a bit and going with 2 passes and actually run the print twice to get clean cut on the blue (so 4 passes in total). I don’t recall if I needed to run the 2 pass print twice on the clear or not…

I just used set focus and it figures it out.

Hi Nick,

This is Deb I may be able to help you round off your corners without sanding or anything. Please pm me and I may be able to walk you thru this. I just did a cut out of 3/8 and had to do three passes also but nice even rounded corners. very nice work.

Happy Creating


Hi Deb, I would be interested too.

I nearly always run acrylic raised off the bed now, then flame polish as well.

But I can’t help feeling I’m still not getting the best, particularly stepping motor chatter on the edges.

I did the same thing when I was cutting 3/4" acrylic. I cut the risers on the 'forge out of draftboard.

Another very simple thing to try before you go the riser method… Just try newspaper under it. I’ve found a simple layer of 2-ply newspaper completely eliminates flashback in most situations, and the height difference is literally paper thin, so you probably don’t even need to adjust your height setting.


I am curious about the mechanics of this, given that the focus range is only 1/2".

Hi nick have you downloaded either program. When you do please let me know. It is so simple to do the corners Deb

I cut 3/8" at 125/full 2 passes and no masking sitting on the tray and get this with just focusing at the top of the material. There’s some chatter at the bottom, but it looks a little worse becasue there’s quite a bit of paint on that one side. How much better/cleaner are you guys getting with three passes and all the focusing adjustments etc?

I’ll have to try this. I’d not even considered newspaper.

I can’t speak to the mechanics since I’m not a mechanical engineer. But it cut nearly completely cleanly at 14 passes. Definitely cut through no problem. It was clear acrylic, but the cut was… cloudy at the bottom of the cut. Almost looked like scratches. Basically it was a little bit of melt. I made several attempts to get a clean cut, but nothing I did made it clear. But really had no problem cutting through it though.

For that matter I once engraved 3/4" deep into 1" wood in a single pass. That was a little scary as it was a little… flamey. The air assist kept it at bay but, man, it was a scary run. I never did that again. Not even sure one can as the speed settings have changed since then. You used to be able to choose a much slower speed, but they (wisely) changed that.

Thanks folks…will report back on things when I get the chance. Alas, my lid has just detached from the hinges at the back (adhesive failure by the looks of it…quite common evidently…). Hopefully, I can get it fixed ASAP.

I finally had time to try the newspaper today and it worked great. Much easier than having to use my riser. Thanks for the tip.

Deb, I did look at the program, but I don’t see how it helps me…corners aren’t my issue, the flashback is and it looks like the newspaper trick may just, well, do the trick!

Hi Nick,
The program is great for the corners of your acrylic.
The menu on the side if you hit it to one will give you a nice finished corner rounded slightly or whatever the number you choose. I always put masking tape on my acrylic. or blue painters tape. Good Luck with r projects.

Ok I miss understood you. I am happy you could sm
solve the problem


Keep trying and testing, here’s results I have with 1/2” acrylic.

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No problem Deb! Really appreciate the thoughts…that’s what makes this forum so useful!