Unable to replicate initial cuts on polycarbonate enclosure (any ideas?)

Community Laser Talk
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Hi Everyone,
I am new to laser cutting and still trying to work things out. I bought a 50W CO2 laser cutter to cut electronic enclosures for my business. I had success cutting my first enclosure at 60% power, 10mm/s (see photos). Cutting the second with the same settings did not come close to cutting through the (roughly 2.5mm thick) material. I then upped the power to 80% and ended up with a charred mess. Upon further tries I have been unable to cut through.

Does anyone have any clues as to what may have changed?

cut_attempt_1
cut_attempt_11569Ă—1245 125 KB

cut_attempt_2
cut_attempt_21848Ă—1520 184 KB

cut_attempt_3
cut_attempt_31855Ă—1479 179 KB

2

It looks like “out of focus” or broken or loose lens…

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3

Hi Bernd, thanks for the input. I thought a similar thing, so I cleaned the mirrors and lenses, and checked alignment. Same result. Here’s where the head scratching really starts. I tried the same settings and pattern on a sheet of acrylic (see photos) and an ABS enclosure, and the results are perfect. When I back to trying to cut the original polycarbonate enclosure… still not cutting.

acrylic_1
acrylic_11241Ă—841 110 KB

acrylic_2
acrylic_2944Ă—666 59.9 KB

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…with the same (correct) focus?

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Sorry for my ignorance on the terms. I assume you mean focal length (ie. lens/head distance from the surface of the material)?

If so, yes. 13mm from the material on all attempts.

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…Sorry. I didn’t read it correctly.
PC is not suitable for CO2 laser, I have tried that too

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Ok. I would have assumed that, had it not gone so well the first time! Looks like it’s back to the CNC machine for this job.

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…I tried a month ago, polycarbonate definitely doesn’t work.

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What type of laser would cut 3mm (ish) polycarbonate?

This article I read does a good job of telling me nothing:

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So I have something to read up on, I’m looking forward to being able to use the PC I have here in storage.

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From what I’ve seen, thin polycarb sheets cut well, but anything more than a millimeter (-ish) doesn’t work. The lead illustration in that article seems to show a very thin molded form with laser-cut holes.

For example, a laser-cut CD:

It may be a case of my 60 W laser not having enough mojo or the piddly assist air not having enough whoosh, but AFAICT 3 mm polycarb is on my “do not cut” list.

As you’ve probably already discovered, polycarb releases terrible fumes:

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…nor me. Maybe they’re referring to fiber lasers…it’s written very loosely.

It’s a shame you can’t hit it again, your first attempt looks better than anything I’ve tried with PC.

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Thanks for the input. I ended up just engraving the centre point and drilling the holes with a step drill. It was surprisingly quick and easy with all the points marked.

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14

Easy solution for difficult challenge - I like that :+1:

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Even though it’s an old post, I want to “update” my part of the PC experience.
I had to cut 3mm PC, a few items, a small order. - (privately I wouldn’t even touch that material with a fire tongs …)
The smell and smoke development were so intense that I feared for a while that someone would call the fire department. I could see thick smoke coming out of my industrial exhaust. Acrylic is not something laser toddlers should play with, but this PC is much worse.
The values ​​I used are 10mm/s and 45% power on my 60Watt (55…?) laser. The edges become rough and smaller holes tend to fuse together again, otherwise for very simple items…ok
It can be done, but if I ever have to laser cut PC again it will have to be at night with a lot of rain and lots of wind :wink:

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