Laser beam wandering at cathode end of tube

[David Killing]

Hi all,
Just setting up my new Ten-High laser cutter and noticed that the beam in the tube seems to be arcing off to the sides at the cathode end of the tube. I'm running it at 25% max power for initial testing. (Short video clip: https://youtu.be/7ctbC4q2qDM)
I am not sure if this is normal or not. It seems to be cutting ok but I don't have any baseline reference.

In the Learning Lab video where Russ installs his first replacement tube (https://youtu.be/_hysBCC_ZwE?t=12), he gets a similar behavior where the beam is wandering. I could not find out whether he discusses in a later video whether this was normal or not.

1. Anyone know whether this is normal behavior?

2. If not, could this be an indication that my distilled water is contaminated or maybe just a bad tube?

If I don't hear any suggestions, I think I'll try flushing the tube and trying new distilled water. Maybe some old water left in there from the factory.

Sorry if this was covered before and I missed it!

Thanks,
David

[Philipp Pap]

At first I really would install a milliamp meter. Maybe you could try with a little bit more power, I don't think that a 5 seconds testing period will destroy/do real harm the laser - on my machine it flickers if I don't have enough power% (just tested it, but here the whole beam flickers without arcing (at 12% it flickers, at 12,2% less flickering but with a high pitched noise and 12,3% solid, without noise)).
On my machine I installed the milliamp meter just a few days ago and I was delighted about how low these readings were (before I measured the output watts and stopped at the percentage where the curve began to begin to flatten out, which is 1/2 of the recommended mAs). But beware, I'm not an expert and it could be another problem... It's a good video and somebody knows the solution/answer and will hopefully post
Are the stated laser-watts and the laser-psu are in the same region?

[David Killing]

Thanks for the reply Philipp!
Yes, an ammeter was definitely on my list to install asap. I am ordering one today. Good to know it really is a useful tool in understanding the machine.
As you say, maybe it's just the low power, and I could try the short test at a somewhat higher power - but I don't want to go too far until that ammeter arrives in the mail!

Thanks again,
David

[Hank Morgan]

Normal. Don't worry about it.
That's fairly normal behaviour for gaseous discharge tubes running at low power. (Low power relative to the size and current rating of the electrodes)
Crank it up a little more and it'll go away.

[David Killing]

That's what I was hoping the response would be. Once I get my ammeter in there I'll continue my testing and report back if anything notable occurs at higher power.

Thanks Hank!

[Doug Fisher]

>>Crank it up a little more and it'll go away.<<

+1