New co2 laser tube looks faulty

Hi all,

Was aiming to replace the 35W laser tube on our machine it started to get weaker after 5 years of age and usage. I bought a new lasertube from Cloudray, but it looks it has some issues with the positioning of the electrode tube within the glass tube. Have seen many tubes, but not one with this kind of deviation.

Have contacted the seller in the interim, anyone in the Lightburn community has experience with this kind of anomaly? It’s inserted on an angle, so that it looks it could partially blocking the beam exit mirror. As well there seems to be a tiny haircrack in one of the glass water connections.

It’s a bit of work to dismantle a running machine which my wife uses for her business to replace a tube with a product which may be defective. The shipping was very quickly, in around one week. Any thoughts? Send it back?

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Some variation is normal, they are rarely 100% evenly spaced when assembled. But that is, in my opinion, far too much. The crack in the glass at the water entrance must not be there at all, I doubt if this tube is at all “can hold on to the water”, the inlet pipe can fall off at any time.
Send the images to Cloudray and ask for another laser tube. Usually they will not even have the defective back because it is too cumbersome.
I will not put this tube in my machine and risk putting everything under water with the possibility of serious electrical short circuits.
Even if you could patch the damage with patex, you have a very poorly placed cathode into the tube.


Thanks Bernd, much appreciated.

I’ve been in touch with Cloudray, they liased with the technical expert, and asked me things such as if I could wipe off the crack which I’ve responded to. They advertised free returns, so I’ve requested a new good quality tube and to provide me with a free return shipping label. I don’t want to risk any shortcuts or a short lifespan of the tube due to the misalignment of the electrode tube. To be continued.

It’s the right way to go, but I’m a little surprised they want the defective tube back. Do you have the right safety packaging material at all? If the cooling coil breaks on the way to Cloudray (which is one of the most commonly seen transport damage) you will most likely get nothing from them.
I cross my fingers for you and hope for the best so you can get started on your work soon.

Update, it’s resolved! I received a new tube (had to break my earlier received tube and send them the video prior). New tube cuts and engraves way better then the old one. plasma colour is purple again instead of whitish and fires at a lower amperage.

Thanks Bernd! Was a bit fiddly to install as the new one had a metal head and as the new water outlet was facing down towards the chassis I needed to raise the tube together with shimming the gantry as otherwise the water hose would kink.

This is good news and now you can finally start setting fire to your projects. The last part of your installation of the new laser tube is a bit unclear to me, water outlet must point completely straight up otherwise it is very difficult to get rid of air bubbles. (You could make a picture so I can understand it better) Congratulations and have fun with your laser.

Bernd is right that the water outlet should be at the top of the tube so that air in the cooling jacket can make an easy escape.

Were you able to purge all the air out of yours?
With the outlet at bottom that seems very difficult without standing the machine on end…

It is generally easier with a cooling machine and a closed water circuit to get rid of air bubbles, but it is not a guarantee either. An air pocket in the wrong place in a laser tube is fatal. When I have not used my laser for a few days, I usually check for air bubbles, it does not cost me anything but a new tube is expensive.

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Yes, getting the bubbles out was an easy task. My new tube has a metal head and therefore the outlet (where you conect the outlet hose on to) must face down (or as ‘good down as it gets down’). A tube with a glass head installs a bit easier (see photos below).

I learned over the years that for me to prevent any airbubbles getting into the tube the top of the water in the container (I use a 20L closed bucket) must be higher then the tube itself (mine is about 50cm higher). I’ve used small tie-wraps to secure the silicone tubes.

A few years ago I installed a polycarbonate ‘window’ above the water outlet, so I can easily check always for any bubbles.

(photo of a similar tube as I have installed, source Aliexpress:)

Old tube with glass head did not have that issue (sort of similar photo, source Aliexpress)

Aha, the photos make it clear how yours needs to mount. Forget all that other stuff I said. :slight_smile: