PF acrylic melting/scorching?

[BeamGeeks]

Hey all! I’ve been working on some game tokens using red proof grade 1/8" acrylic. It cuts just fine for the most part, but I always get areas of scorching and melting on the back of the material. I’ve tried with and without the backing. It’s most noticeable around some small lettering. There are other areas of noticeable heat bloom as well. I’m not sure what I can do do avoid or fix this, but it’s putting me off a bit. I plan to work mostly in acrylic but I feel like there’s a lot to learn about this medium.

I’m using a mono-line font, so it’s not doing a double pass. And now that I think of it, for some reason the GF software is making the outer circle a double pass even though there’s just one path in the file. I’ve seen it do this before but I’ve never been able to figure out why that would be. On the last one I cut, the first pass dropped the material down and then the second pass messed up the edge since it was sitting a bit crooked. What gives?

I’d love a little advice, here, since I’m getting a bit frustrated. I feel like I’ve tried to make a sensible pattern that should cut well, and it’s just not working out. I even went as far as making about 7 layers to space out cuts that were too close together, thinking the heat would dissipate and I wouldn’t see as much bloom and distortion.

[Lotema]

You might want to put some extra material (thin card stock or cardboard) under the piece. You might be getting some flashback from the laser hitting the grill under the piece. Sometimes even the backing paper isn’t enough to really protect it.

[BeamGeeks]

I thought about that, and that’s why I removed the backing from just the area I was cutting. That essentially means the backing was the extra material that was holding it up just a touch.

[BeamGeeks]

Or do you mean leaving the backing on AND adding a layer? If that’s the case, do you have to change the material height in the settings?

[Lotema]

Yeah, sometimes that doesn’t seem to be enough though. I had a huge acrylic piece I ran a couple months ago that had the backing on it. It gave me these weird squiggles on some of the border areas that drove me crazy trying to figure it out. Then I realized that it followed the pattern of the grill under it. I wound up cutting up the cardboard soda case from my recycle bin and put that under the piece. The weird deformations/squiggles went away. That grill can get pretty toasty when it gets zapped with the laser.

[BeamGeeks]

Ah. So did you tweak the settings at all to compensate for the added height?

[Lotema]

Ideally you would adjust it a bit. I didn’t think about it at the time and just left the settings as is and my piece still came out looking great. I would certainly adjust if I were putting a thicker cardboard under it.

[BeamGeeks]

Great. I’ll give this a shot and report back.

[hansepe]

If your cut is making two passes you have two paths (lines, circles, whatever) in your file whether you can see them or not. If you want to post an example of your file there are generally plenty of people that will take a look and try to help.

For the material falling away, you can fix that by keeping the material flat, use magnets, clips, whatever.

An index card can be enough to stop flashback on your piece, anything with discernible height needs to be factored into your material height calculation.

[Jules]

You might want to try just scoring the text instead of cutting all the way through anyway. Unless you want it to show through on both sides.

[BeamGeeks]

Yeah, it’s supposed to be double sided so it’s gotta be a cut.

[hansepe]

Also, you have some control over cut order by using color properly. Check this thread out:

Custom Inkscape, Illustrator, CorelDraw and Affinity Designer Color Palettes for ordering operations in GFUI

Continuing the discussion from Space Invaders or Mitral Valve Leaflets, you decide: I have always been curious about how the Glowforge defaults the order of operations. I have tested it in terms of position in the workspace and order of creation in the design. Nothings seemed to click right, but I had a sneaking suspicion that it was dermined by color. The Glowforge catalog designs always load in the same order, though you can drag and change them in the workspace, so I figured there must be so…

[BeamGeeks]

I totally found a hidden path right after I posted. That was just a rookie mistake. Thanks!

[Jules]

You can do scoring on the backside as well - then the text will read correctly.

Write-up on the process here:

Glowforge Interface - How to Get Perfect Alignment (Yes, perfect!)

So by now, everyone who has gotten an early machine has experienced having their object placements using the lid camera be off at one time or another. That’s likely going to continue until the folks at Glowforge tighten things down on their end. (Not going to lie to you, it could take multiple months. It has taken a minimum of four to six months with every single machine I’ve ever gotten involved with testing on. If you don’t want to deal with it and haven’t received your machine yet - just …

You’re going to want to either do a very light score though, or convert to an engrave, to keep from punching through in the corners.

[BeamGeeks]

Wow. Just simply adding a piece of cardboard behind completely eliminated the scorching and melting, which was obviously my main issue. Thanks!

[BeamGeeks]

I’m still getting some double cuts on the letters, and the outside circle. I thought I got it but I guess not. Anyone want to see if they can find the extra lines?

[hansepe]

That’s an interesting file. I played with it a bit.

On your original file you’re going to keep burning the $%!# out of the text because of the serifs (the teeth will continue to be a problem too). I made a second copy with a different font, that shouldn’t be as problematic. I put several different colors in to discriminate the layers, but that is easy enough for you to change.

The double cuts should be gone.

Good luck.

(new text) EDIT: This text will not cut right, A will be problematic

(original text)

I loaded both files in the GFUI but didn’t try to print them.

[Tom_A]

leaving the backing on AND adding a layer? If that’s the case, do you have to change the material height in the settings?

I’ve had great success with 2-ply of newspaper. It doesn’t affect the height (in any significant way) and it seems to reduce flashback to 0.

That said, I think material settings should always work without scorching or modification. So I think they should tweak the settings and/or the material and/or the backing as needed.

[kittski]

I’m still getting some double cuts on the letters, and the outside circle. I thought I got it but I guess not. Anyone want to see if they can find the extra line

Hansepe fixed the file, but I wanted to make sure you saw the double lines in the text. (I ungrouped everything used “wireframe” view in Corel to find them.)

[BeamGeeks]

Thanks for the help, everyone! I got it all sorted.