Could misalignment of mirrors cause the pulse spot to become a line? Line is approx 1mm in length.
Assume you mean width?
This is most likely a focus issue, from what I can see. I’d suggest a ramp test to ensure that’s the finest line or best focus. It’s too big all around.
If you have:
- properly working tube
- clean and aligned optics
- proper focus
They work…
Ensure the optics are clean.
This can also be caused by the tubes TEM mode.
If you use a minimum power setting, you can eliminate the burnt corners. I’d guess you have both minimum and maximum the same or nearly so. Not going to fix the optical issue.
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I have checked the laser paths’ alignment and it’s hitting dead center on mirrors 2 and 3. But the pulse is still not a proper spot. Could it be deflecting off the inside of the nozzle?
Any guidance on how to tweak mirror 2?
Have you check the tubes output prior to m1?
No, what should I be looking for at the tube?
This is often a problem. If your nozzle is not perpendicular to your machine bed, the laser beam can hit the inside of the nozzle cone.
What Jack means (probably?) is that the semi-mirror itself in the CO2 tube can also be a bit dirty, I use a cotton swab with technical alcohol to clean its outside.
Have a target before m1, so the tubes output strikes the target before anything else, that will show you the TEM mode of the tube. It has to be very light so you can see the power distribution across the beam.
It should be dark in the center and move outward, evenly getting lighter. If there is a doughnut shape or some other aberration in the beams output, that could be an issue.
All the mirrors do it get the beam to the lens, the lens only makes what it sees smaller. If you start out with a poor source, it can’t help.
You should always check the optical path for it being clean, that should be understood when you do an alignment.
Make sense?
Yes, I understand, thanks I will check it in the morning.
I see what you mean. I’ll pastry a card or painters tape over the orifice and hit pulse to check the pattern as you have described.
There other thing is the nozzle’s true, well try that with the same tape method over the nozzle tip to check for center
When it’s operable enough to cut 3mm acrylic, this tool centers the nozzle over it’s center and you get 5 pulses per piece of tape. I keep at least one around.
Beam Checker 2.lbrn2 (12.2 KB)
If you can run it without the nozzle and see if the results change to see if it’s hitting something inside. Usually the nozzle heats up a bit from the beam.
HUGE Thanks to ALL that provided precious advise. I managed to resolve the issue. The pulse spot is now as it should be, a DOT. It is cutting and engraving as it should be. Much appreciate all your time.
Cheers,
Patrick
That’s great, but leaves the rest of us that has helped you and anyone with a similar issue in the dark.
What did you do to resolve the issue?
Part of how this is supposed to work, is when someone solves the issue, they post the solution. That benefits all the people helping you (educational wise) along with anyone that’s trying to solve a similar issue.
We know you know, how about telling us?
Thanks —
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Apologies for not adding more info with regards to the issues I faced earlier.
The “line” shaped pulse spot was primarily due to misaligned mirrors. So I made the necessary adjustments to the mirror 1 (nearest to tube) until I got pulses that matched on masking tape (mirrors 1 and 2). Then I made a pulse and got a fine dot on a scrap piece of ply. Hence the nozzle wasn’t off centre at all afterall.
Made a couple of test cuts and engravings and all’s well.
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