OMTech tubes… I’m assuming these (and anything in the same price range) are junk. The stock one lasted ~240 hours and the replacement they sent me is already failing at around 50 hours of use. (What I was cutting at 45mm/sec about a month ago now needs to be cut at 6mm/sec)
Before I order a new, higher quality tube, I just want to double check if it’s something I could be doing to cause this… although I don’t think it is. I’ve never run the power over 75% (digital and analog meters read ~18mA when the tube was brand new, ~20mA now at the same settings), my chiller keeps things a fairly constant 18-19*C, and the stock power supply was replaced.
I’d qualify that there’s a difference between whether it should be failing under those conditions or whether or not there’s something you can do to improve longevity with whatever tubes they’re providing.
You’re likely running too high. Certainly 20mA is higher than the “Optimal Current Rating” of 15-18mA that OmTech lists. And if they’re giving you a range I suspect the lowest value is really the nominal current. So if you’ve been running at 75% at 18mA and over you’ve likely been overdriving the tube.
Even at High Power 70-100% OmTech lists 800-1000 hours of use. I assume that’s in the best case. The 240 hours in that case doesn’t surprise me.
I suggest if longevity is your goal that you run quite a bit lower than what you’re running now. Or get a higher rated tube and LPS so that you’re running at the low end of the power range.
OmTech lists 13-15 mA as optimal operating current for their 50W tube so surprised you’re not having problems at 17mA. Does your test certificate list the mA it was tested at?
They list the same 800-1000 hours for lasers run at “high power” as on the 60W.
@thestip, do you have any other unique things going on in your environment? Perhaps especially noisy mains power or a lot of mechanical vibrations? Is your laser perhaps not level? Do you have any air bubbles or unfilled areas of the tube that would potentially reduce cooling efficiency?
When the machine came it had a ‘test’ sheet where it stated maximum current, but the wattage was blank… curious … Notice the manufacture date…
When I got it, that is my first co2, so I was learning… I know a bit more now…
I think Russ suggest to purchase from Cloudray as they sell only grade A tubes…
I guess, we’ll see how long this lasts… I think I might get one of the spt types that has a built in red pointer… Might be novel to actually have one that works…
I saw that and it intrigued me. Curious if it’s worth the extra cost. Cloudray also sell a beam combiner that is used as a replacement for mirror 1 that’s interesting but not sure if it’s worth the cost and hassle.
Just ordered a new 60-80w from Cloudray. I’ll have to extend the case to hold it, so I’m thinking about getting their cheaper beam combiner too since space won’t be an issue any more.
I read a post some time ago where a guy adjusted the power supply so that when he set the power to 100%, it was whatever the rating for his tube was. Seems like a good idea, but I don’t think I’ve seen anyone else do that.
Did you ensure the diameter is the same as your current tube or have made an adjustment for that?
That’s what we were talking about earlier.
When your tube lases, it does so at 100% only limited by the lps current. You don’t want the lps to allow more current than the tube should have… it needs to be adjusted at the lps.
This is easiest on LPSs where there’s an accessible potentiometer that allows adjusting current. You may want to check yours to see if there’s one available.
Don’t have one now… if I buy an spt, it’ll be novel to have one… I removed mine after a couple weeks or so after getting the machine, never have missed it… came off when I replaced the head.
Even using the ‘pointer’ it was always off and had to be readjusted for each lens change. The ‘dot’ was so big (or bright) there was no accuracy on anything but acrylic where I could get the a properly set pointer correctly aligned…
I had difficulties with a pointer and started using jigs and so forth to hold stuff. A couple times I’ve used the location pins that are on my table using the pass-through in the machine…
It would be nice to be able to use one, that’s why I figured I’d buy one with a factory set internal combiner (spt). That would be the most accurate…
It actually came off permanently when the head was being replaced. I realized the only reason I still had a drag chain was the led (I didn’t use) and the air assist… so I cut that tab off the head bracket and got rid of the chain and led… The tube is very flexible…
Probably one of the reasons I can run 1650mm/s… much less mass.
That’s exactly how they list that tube. 60-80w with 20mA max. Assuming 20mA gets me 80w, but I’ll still shoot for 60w.
This is 5mm wider, so I got new mounts.
the pot’s not in the best location, I think I need to pull the ps… I’ll look again. It came with an adjuster knob/display, but it only works on 100+w supplies. (so why include it?) Worst-case, Cloudray sells a cheap adjustment kit.
It’s rated for 60w, but apparently has no problem pushing 20mA
