Thunder Laser Polycarbonate Settings

I have seen several people on here mention that you are able to cut polycarbonate on your Thunder laser. We have a new Thunder Nova 51 130 W machine and are looking for some settings to get us going. Does anyone care to share their settings for polycarbonate?

When cutting, do you remove the protective film or leave it on? Any other tips/tricks?

Same boat. We have a Thunder 130W Nova 51 and would love to know how to safely cut polycarb as well. We have the 6" blower vented directly outside right next to the machine. I’ve heard all the reasons why you shouldn’t cut polycarb on a laser (toxic fumes, white particulates inside the machine, degraded optics, yellowed/discolored edges, etc.) but I have also heard of people successfully cutting polycarb on a laser so I would love to know the secrets as well. @AllenGregoryIV ???

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Tagging @Cory as well

The best tips/tricks I’ve seen came from @ToddF.

Not sure about settings. I’d think the key setting would be speed, cutting as fast as possible while getting through the material.

A couple things to say about this:

On safety

The world is full of interesting and useful construction materials that, when combusted and/or vaporized, become incredibly dangerous to you. There is nothing nontoxic about polycarbonate fumes from a laser cutter; they absolutely are toxic.

If you can smell it, it is harming you.

It may have been harming you since even before you were able to smell it! Getting a true answer to this requires doing science with pretty small numbers, which is hard.

.
On 2363’s recent experience

After cutting nearly our entire robot from polycarb on the laser in 2020, we struggled mightily with the same equipment 2022, sinking dozens of hours into troubleshooting the machine and earning near-zero reward for our effort. We did however use the laser quite a bit as a marking tool and then cut the parts by hand with band saw / drill press. We made our Everybot climber that way, for example.

The work still isn’t over; we in the process of transplanting the entire machine into a new frame which will feature improved ventilation and more dimensionally-stable mounts for the optics.

You are right of course, but also almost everything creates toxic fumes when burned, even plywood. I haven’t been able to find any source to say Polycarb is unique in that regard. Laser cutters need good ventilation period.

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As for settings, I need to double check, but I recall our ~100 W cutter does 1/4" thick lexan at 90% power and maybe 200 to 300 mm/min with a strong air blast when the lens is clean, and the mirrors are aligned well.

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I’ve posted this in a few places but the keys to cutting polycarb are lots of ventilation and lots of air assist (air blast).

Our laser is connected to our way over spec’d shop dust collection system and our shop air compressor. Even with that it won’t cut true 1/4" polycarb nicely but it will cut 6mm polycarb (I imagine we may be able to do with the different lens that has a longer cutting focus).

When we cut we make sure to fully cut material in one pass so that the air assist and dust collector can effectively extract the smoke and nothing is visible above the material so it doesn’t damage the optics. We also can’t small anything in the lab when we cut polycarb, but can if we walk outside near the dust collector.

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Allen, Would it be possible for you to post here the actual settings you use on your Thunder for say 3mm/.118 polycarb and 6mm/.236 polycarb? Ar you running LightBurn? Maybe share your tuned setup files?

Is yours a 100W or 130W?

100w, and the settings change semi-regularly based on the cleanliness of the mirrors and lens (We don’t maintain things as well as we should) and the specific material we are cutting, but these are a good starting point.

Lexan 1/16”

  • 50%
  • 10 mm/s

Lexan ⅛”

  • 65%
  • 10 mm/s

Lexan 6mm

  • 75%
  • 5 mm/s

We try not to run the laser above 80% power if possible; if I could do it over again, I’d have gotten the 130W version of the 51 instead of the 100w Nova 35.

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So does anyone know if the % power scales linearly? For example, for Allen’s 1/8" at 65% is it safe to guess that would scale to about 50% on a 130W machine?

My recommendation is just to cut some sample pieces on your machine. We will regularly just cut 1" circles and see how it cuts. We do this even just to check how the laser cuts in different areas of the bed. Since our optics aren’t perfect, the top right corner normally cuts cleaner than the bottom left, so we have to up the power or lower the speed on bigger parts, etc.

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Thanks Allen. Do you leave the paper/plastic masking on or take off? We usually remove the paper masking from the top side on acrylic cuts but leave it on the bottom and remove it after the cut. I tend to take the plastic masking stuff off altogether because I don’t know what it is.

Agreed with Allen, this is something we do empirically. It’s a good question though… One problem is that there’s multiple “power” and I don’t think any of them scale linearly with the power setting.

  • Heat flux to the workpiece
  • Beam energy
  • Electrical energy pumped around the high voltage circuit by the laser PSU
  • AC power consumed by the laser PSU

Also, most of these are real hard to measure quantitatively.

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