this post was submitted on 12 May 2024
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Laser Cutting

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Turns out a misaligned mirror made the laser hit the lens in a weird way, and then bouncing off something on the way out to produce this double line. Probably. What kind of strange troubleshooting have you done and what was the reason/fix?

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[–] [email protected] 2 points 5 months ago (1 children)

To me this looks like it could be due to backlash. Did both lines appear at the same time, or are they from two different passes.

[–] [email protected] 1 points 5 months ago (1 children)

One pass. What does backlash mean? (I'm kind of new to this) Aligning the mirrors did stop it from happening again, but maybe that was accidental?

[–] [email protected] 2 points 5 months ago

Backlash is the play in the gear train. It would be evident if the cut was made one direction then the other. Seems like you had a different problem. Never seen that before.

[–] [email protected] 2 points 5 months ago (1 children)

Is the glass separating from the mirror layer or something? I've never seen anything like this but it reminds me of the double reflections you get from mirrors with thick glass.

Or maybe it's so misaligned, the laser is hitting the edge of the mirror...?

[–] [email protected] 1 points 5 months ago (1 children)

The mirrors seem fine. I don't really understand it but aligning the mirrors made it go away.

[–] [email protected] 2 points 5 months ago (1 children)

Could it be hitting the nozzle? That would be a very minor misalignment so it might be hard to notice

[–] [email protected] 1 points 5 months ago (1 children)

Could be. Is there an easy way to test that? For the mirrors we had pieces of paper to see where the laser hit.

[–] [email protected] 2 points 5 months ago (1 children)

Can you take the nozzle off for a quick test? Mine unscrews for cleaning, not sure if they all do though

[–] [email protected] 2 points 5 months ago (2 children)

I could, but it's a community laser cutter, so I'm a little reluctant to take things apart now that it works again. If the same thing happens again, I will try that for sure though!

[–] [email protected] 1 points 5 months ago

Ooooh yeah, not quite your place to be fuckin with it haha

The workshop manager (or whoever is in charge) hasn't tried to fix it?

[–] [email protected] 1 points 5 months ago (1 children)

Oh followup question!

Do the double lines only happen in specific areas of the cutting bed?

I was getting weak cuts in the lower right of my machine due to some misalignment. Presumably because that's the position where the mirrors are farthest apart

[–] [email protected] 2 points 5 months ago (1 children)

I didn't do enough tests, but it appeared more or less in every part of the bed. The guy who is an expert on this particular machine came and aligned the mirrors so it works now. He did say that the back mirror was most misaligned, and that that should really not be possible or something like that.

[–] [email protected] 1 points 5 months ago

Yeah that is pretty weird. The rear mirror is fixed to the body of the machine, it's usually the front mirror that rides on the gantry that gets misaligned "naturally"

Maybe someone smacked it on accident...somehow lol