Material smoldering on complex busy pattern

I’m having a lot of trouble cutting and engraving with my new Atomstack S20 Pro. My preffered material is 1/4" aspen plywood because I have access to lots of it for free. I need to make multiple passes (6 or 7) on cut path to get through without causing the material to smolder, but when these are small pieces near each other too much heat is building up from adjacent cuts and causing the material to smolder. I tried assigning various levels of priority to keep cuts from occuring next to each other without adequate time for the area to cool, but not enough apparently. I appreciate that LightBurn optimizes the path but in this instance I actually want the least optimized path to give my material enough time to cool in between cuts. I suppose I could create a phantom layer that just eats up time without doing any cutting or engraving…

I’m disappointed that the laser I bought can’t do the things that I want it to (yet?). I’m looking for suggestions on how to use it more effectively. Lower/Faster Speeds? Lower/More Intensity? Larger distance between cut out areas? I imagine a better machine would cut this more easily but I’m struggling to find the right parameters to cut and engrave with what I have. Is my material the problem? I’m still very new to all this so what else am I missing to help someone diagnose my problem?

Cut Settings: Speed 550 mm/min, Power 85%, Number of passes 6. Space between cuts 1/8"

Engrave Settings: Speed 2500 mm/min, Power 50%, DPI 254. Grayscale.

Material: 1/4" Aspen, 3 ply



Is there a reason you can’t run it slower? Like at 1mm/s (60mm/m) or even slower? It might do much better and air assist would help if you could do it in one pass.

Why are you limiting the power to 85% for the cut? Are you uncomfortable running at greater power levels?

In theory, cut the speed in half you effectively double the power…

You’re at 550mm/m@85%, that’s ~9mm/s, cut it in half twice you are still moving 2.25mm/s… you could cut it in half again… down to 1.125mm/s… and even further. This in itself would make a deeper cut on each pass.

You will have to figure out how to get through that with less than the number of passes you are using. I suspect there is a focus problem, dirty lens or something restricting what it’s capable of… or just running too fast.

I looked this machine up and they claim it will cut 12mm Solid wood Cutting in One-PASS. I don’t think I can do that with my co2…

MDF is usually more of a problem, because it’s glued together and the glue is a problem for laser cutting. It will range from a big puddle to non-existent, so it’s rather unpredictable.

There are a couple of other things you can try…

First and most important is focus… I always suggest you do a ramp test of any new laser and ensure it is focusing where they claim… I’ve seen many of these that didn’t perform and there was a focusing issue. Once that was fixed it cut well…

Make your focus point more at the center of the thickness. That will allow the deeper depth of field. As your laser cuts deeper, it naturally changes focus as the material burns away… If your focus is part way down it can put more power across a greater depth.

Addition of air assist really helps. Just how much, I can’t advise for your machine, but it was night and day difference for my co2 when cutting. Small pieces are an issue as the air assist may blow them into the laser beam…

Do a ramp test and ensure it’s focused at the proper point.

Another claim of theirs is 8mm Acrylic Cutting in One-PASS

A visible light laser cannot cut acrylic as it passes through the material and doesn’t excite it. You can only cut material which will block the lasers frequency. If you use black acrylic, you are heating the the black pigment and that heat melts the acrylic. If it could cut acrylic, it could cut any type of acrylic, including clear acrylic, which it cannot.

If it can cut 12mm hardwood, I’d think you should be able to do 6mm mdf…

Good luck


Thanks Jack, this is all really helpful.

I’m comfortable running at higher power levels. I perhaps believe incorrectly that running things especially electrical components at less than their full power can help elongate their lifespan.

I ran another focus test with a greater slope than I previously had done, and got an interesting result: the line started broad on the low end of the slope as it should but it just narrowed until the laser bottomed out and never got broad again. This leads me to believe that my focus depth should be as close to my laser as my material will allow.

Just to be clear, the material I’m using is 1/4" aspen plywood

I ran a new cut test file. Focus and slower speeds did a lot. A much cleaner cut, with much less soot and char, and a pretty square edge actually. I’m still using six passes to let things cool down. I know now that AtomStack made that claim of being able to cut 12mm in one pass but on their website they have some suggested settings that seem contrary to that statement.

There are a lot of variables, I’ve learned, that have to be honed in on before a cut let alone a clean one can be made. I watched a lot of videos and read a lot of tutorials, and downloaded a lot of cut/engrave test templates without understanding that I was going to have to play with four major variables before I found the settings for my machine: speed, power, focus, and number of passes. Fortunately, LightBurn has made working with those easy, even if my machine hasn’t.

Thanks Jack for getting me back on track. My next test will be for those close proximity cuts.

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.