Thick and expanding laser beam out of tube - help!

[Krzysztof Smaga]

Hello!

I did a routine maintenance around our machine lately and went a bit deeper, cleaning tube outer surface, leveling the tube aligning mirrors etc.
We observed quite a loss of quality and power lately - that was the motive behind it.
We own this machine for 3 years now. it works mainly cutting paper and plywood - never exceeding safe current for this tube - RECI 130W

As i quickly found out the beam itself was thicker then usual coming out of tube - it also wasn't concentrated in the middle , but created a ring on outline of the burn mark. The beam itself is not pararel but it's slowly growing to reach around 14-15 mm diameter on the farthest X and Y axis position.
It's barely fitting to hole in lens head...

I made a short video illustrating burn mark on plywood at 15 % power - https://youtu.be/fYOWYu8leGQ

Have you seen anything like this? Is ti fixable, or should I look for new tube?

[Dave Vigness]

If your beam is not 'straight', you have a problem internal to the laser tube. Start shopping while it's still operational.

If I had my choice, I'd get an SPT tube, specifically the TR series with the integrated red dot. If you are US, Ruka in Florida sells them. https://ruka.world/

[Gene Uselman]

Dave- that does not seem to be a good link.

[Dave Vigness]

Evidentially they changed it. I was redirected to https://shop.ruka.world/

[Krzysztof Smaga]

Thanks for swift responses!
I swapped power supply today - no effect. Started looking for a new tube.
I looked for SPT reseller in Poland and they also told me to look at EFR ZS series tubes - price is just a bit higher, but as they said it is much better quality. You know German glass etc. ;D
Have you had any experiences with those EFR tubes?

And one more question - I think I will downgrade tube power to 100 W - seller told me to also change power supply, but frankly I would like to save my money as I have two perfectly good units on shelf.
Possible problem would be that I have P6 38mA power supply so I'll just use 28mA as maximum and it would work just fine. Am I wrong?

[Gene Uselman]

I have been running a EFR 130w tube for over four years- almost every day [including weekends], I believe they are considered as good as Reci.
Your 130w PS will be fine with the 100w tube altho I would not be going to a lower power tube personally.

[Krzysztof Smaga]

130W was always a bit too much for my purposes - we cut and score a lot of paper and scoring was always at minimum of tube working current, there wasn't much space for adjustments (eg. 8.5% wasn't waking the tube, 8.7% was ok and 8.9% was going through the paper. And with every paper there is a slight difference in how they evaporate.).
Shop also claims that this EFR ZS type tube is "industrial quality" and have a smaller, more concentrated beam, paired with high grade US mirrors it yields much more power then "normal" 100W tubes.
I'll ask elsewhere tomorrow to see if it's not the dealers "smoke and mirrors"

[Dave Vigness]

Dropping from 130W to 100 W tube on the same power supply will not be a major problem. You may loose some fine low end control, but it's not like you were doing photo engraving with it in the first place.

That said, if you are really wanting to do some of the low power work, it may be worth it to invest in the smaller PSU, or maybe even a shade under. As long as the PSU will handle your tube you are good. A 1% drop on a 90W supply is a whole lot smaller than a 1% drop on a 130W supply.