Newer PSU, suddenly no firing.

[Axeman]

So I've yet to have a bad tube. This is my first tube...about 350 hours on it. I wasn't 'fair' to it at all in the beginning..probably the first 50 hours or so I was pushing more amps than I knew since I was new to the laser thing. But after that I made sure not to push it harder than 17mA.

But how does a tube actually die? Does it just outright stop firing? Does it go weak? I've gone through a few PSU's and I know they stop firing altogether...but since I have a nicer version from Light Object, it has a test fire button and an LED indicator to show it does have some juice going through it. Since I don't have a multimeter that can handle 20,000 volts and there is no connection passing through the tube...I'm not sure how to measure if it's the PSU or the tube.

Bad time for the tube/PSU to go bad so I'm really sweating on what to do about this.

[Axeman]

K, I went and took a GOOD look at the end of the tube.

The end electrode looks slightly off, there is a strange piece of metal ring that attached to the electrode and there what I THINK is a small crack in the glass near the exit port of the water line.

Damnit.

[Axeman]

So...as a followup question.

Is there a difference in quality/type from a 700mm tube to a 830mm tube? They are both 40W but...is there differences? Lifespans?

[Tech_Marco]

You sure don't want to measure the 'voltage' from a power supply as it may go from 18Kv to 38Kv and you won't find a voltmeter can handle such high voltage without a resistor divider and a high voltage probe. For CO2 laser, what you need is an ampmeter to meaure current flow. For a 40W laser tube, usually it run at 18mA for full power. For a 60W laser tube it run at 22mA or 28mA for a 80W tube. But, if you want to get long life on the tube, even Reci recommend 28mA for their 100W or 150W tube when it reach full power at 30 and 32mA recpectivily.

When a Co2 was over current and dying, there are a couple signs: electrode turned into deep purple color, weak output or no output but the tube still light on, light jumping around inside of the tube... there are thesymptom of a dyning tube.


Marco

[Tech_Marco]

So...as a followup question.

Is there a difference in quality/type from a 700mm tube to a 830mm tube? They are both 40W but...is there differences? Lifespans?

Oh you bet!

We just tested a new 850mm tube shipped from a high reputation manufacturer in China. Unbeliveable to see that the beam was so good and we could get a tiny and solid dot (burn mark) with low current (2mA). Before, we could only get a donut ring or inregular dot or fuzzy burned mark. Hardly we could come up a small tube with such high quality burn mark. Wow, impressed!

Note, a 'donut' ring isn't bad for a high power laser tube when running at very low current. For high power tuble like the Reci 100W, you got to have mini 4~5mA to get beam cover up the internal mirrors or 'donut' ring happen. When firing at low current like 4~5mA at distance 5ft away, you may get a nice donut ring but it will fill it up once you turn current higher. But for a small laser tube like 40W or 50W, a good tube should be able to get you solid round burn mark in 5~6mm diameter. I was surprise to see a tiny dot (low current testing) when firing a 850mm tube in 1" or 2" away from a piece of paper. I'll post some images later.

The worst case is that the burn mark was not a round but appear to like a char of numberic "8". Or, the burn mark was not solid but in fraction of a ring. It is caused by mis-alignment of the internal lens/mirror from the laser tube iteself


Marco

[Axeman]

Well that's good to hear...I may just go for that since I'll have to get one either way.

Yeah, I know what your talking about with the little fuzzy donut/ring. That's what I always had.

I pulled the tube out and on the backside of the electrode is a big char mark against the glass. So frustrating.

When do you usually ship out? Mondays? Weekends? I may be putting in an order for a large tube very shortly.

[Tech_Marco]

Too late to ship it out today. Plus, I have to test more tube to confirm what I found
Monday is the earlier we can ship

Marco

[Axeman]

K, good to know. I'll be ordering mega express since...I have until Friday to confirm or cancel an upcoming event I have (which will end up just to be paying this set back off )

That's ok for the testing...I'd sooner know that I'm getting a high quality and reputable tube from you instead of a no-name mystery tube. I can get them for cheaper...but I've already learned what that leads in the laser industry. Crappy parts

[Axeman]

Ugh, I have little over 1/2" of 'play' in my system to allow for a 850mm. I don't think I can chance that...that is just way too close. That sucks so much.

[Tech_Marco]

Seems I promised too much on the tube what if....

Anyway, what did you mean? You mean "1/2" space from the mirror or got half power output?
For 850mm tube, we can ship USPS Priority Mail that take 2~3 business day only
Plus, we will test it before ship so that you know you will get a good tube.


Marco

[Axeman]

No, in my machine if I shove the tube right against the mirror, I have 1/2" space from the wall of the laser body (and sitting far too close to my stepper motor). I will down the road, rebuild the gantry to allow for larger tubes...but with me needing my cutter working in the next 6 days, might not be the best time to start hacking my machine again.

But yeah, later I will switch up to 60w or 80w & PSU instead of buying another tube. Make it worth my while.

[Tech_Marco]

FYI, we measured the new tube and found that the "850mm" tube is actually "830mm" in length.

Marco

[Axeman]

Thanks Marco, good to know.

I think what I'll do instead of constantly fighting with this creature...I'm going to work on an entirely new frame that will combine a beam expander + a larger tube to allow for a monster work surface and room to have a mounted tube instead of a gantry mounted tube which just causes huge headache for upgrade later.