i just had my first expierence with cutting acrylic on Donner. When the cut finished there was a strong smell similar to superglue. I was wonder if the exhust was hindered or if this was normal? I cut 1/8 black acrylic with the paper off ,2 passes. Also after the cut there was a very thin layer of residual sticky material on the surface of the piece.
Just saying. I’m new and I not sure. BUT, “you see it…say it!”
This wasn’t PC / Lexan, was it?
Not sure I’ll check! Thx
I cut a bunch of Acrylic last night and yes it smells. I wouldn’t describe it as superglue smell, but it definitely has an odor.
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If you managed to cut it in two passes, it probably wasn’t lexan. That tends to produce thick clouds of smoke and yellow charred edges.
It sounds pretty reasonable. There can be a thin strip of goo along the cut line that can be cleaned off easily. Even with the massive exhaust fan and all the ducting, the exhaust port on the thunders is small and blocks a lot of flow, especially if the covers below the laser bed have been put back on, so I wouldn’t be surprised if you noticed some smell after the cut.
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Yup. That’s the stuff.
Is there any problem there?
Corrrct that. Not the clear stuff. It was the black stuff.
I was told the clear stuff was polycarbonate and can’t be cut in the laser… it forms cyanide gas…
The large squares of clear plastic in the large pile is / was Acrylic when, I have cut / engraved it without any issues or gas. I know a few other members also use it on the laser without issues.
Thx for that! Cyanide is a definate NO NO!
But, how do you tell if that clear plastic is safe or not?
I was told it was left over from covid protection plan .But, that’s third party info.
Anyone know for sure?
The smoke gray strips are Plexiglass, not Lexan and are fine. @keoliver may know more about the clear stuff.
Looking further, the issue with Acrylic is not that it outgasses anyting in particular, it’s that it absorbs and diffuses IR, doesn’t cut at all well, and is prone to catching fire.
Polycarbonate (aka lexan) shouldn’t be cut, it creates thick smoke which tends to block the laser and reduce cut power, and even then it doesn’t cut well.
Acrylic (aka plexiglass) cuts great but you may have some residue depending on how the laser is set up and the exact material. Engraving can vary based on how the sheet is manufactured.
ABS shouldn’t be cut, it’s difficult to cut and can produce some small amounts of cyanide gas, which DMS has decided isn’t worth the risk.
Both acrylic and polycarbonate often come in thin clear plastic sheets. Acrylic tends to be more brittle whereas polycarbonate will bend further before breaking. Google probably has some better ways to tell them apart, but visually they can be indistinguishable.
Some online laser services will cut thin polycarbonate or abs if you need, but they’ve decided it’s worth the additional risk/maintenance. We’ve decided it isn’t.
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Appreciated
Further, the general rule of the laser area is that unless you know explicitly what it is and it is on the approved list, you should NOT be using it in the lasers.
There are some exceptions for this: if you know what it is/ have the SDS, but it’s not only approved list yet- you can submit it here or to the chair (currently me)/ vice chair, and we will review/ determine if it’s safe for the lasers.
(That being said, the clear acrylic sheets that were over by where automotive will be have been confirmed as acrylic and laser safe. Note that there are a couple different types of acrylic if I recall, cast verse extruded and they do act differently in the laser. A slate residue is somewhat expected with them, although generally, if it’s more than a tiny bit, it means that you’re using too much power or moving too slow)
Also: the laser should be left closed after it finishes cutting for about an extra 30 seconds at least. This usually helps remove all major odors. we should have a little bit better ventilation when we move to the other side and get some of that stuff cleaned up
The black donated stuff is plexiglass brand cell cast acrylic and is great for laser or machining . The clear donation is acrylic but it is extruded and not cell cast . Cast acrylic generally lasers and machines better than extruded but both are safe . The general clue as to which you have with new material is that extruded acrylic has a plastic liner sheet when new and most cast acrylic has plasticized paper . Also, if you bought it at home depo or Lowe’s it is likely extruded . Extruded better optically but is more prone to chip or melt when machining so your speeds and and feeds have to be adjusted . Extruded also solvent welds and thermoforms a bit better than cell cast .
Also as to the clear donated stuff measure its thickness and do not assume it is .250. There is lots of variation.
We have some committee stock of polycarbonate but it is not available for general use like the donated stock. It is for DMS committee projects like guards etc.
Hope this helps .
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Be careful cleaning lasered acrylic with isoprop. The laser process causes excessive heat stress micro fractures and cleaning with isoprop causes the fractures to expand, resulting in spider web cracks.
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Ouch. Thx for that. What can you get the filmy residue off with?