My laser cutter was getting worse and worse cutting this batch of shields even if I used a ridiculous number of passes.

I finally checked the color of the plasma in the laser tube and it was white. A CO2 laser tube is essentially just a neon sign tube with some extra mirrors, a water cooling jacket, and a reservoir for extra gas. The mirrors and a specific gas mixture are what makes it work as a laser. Like a neon sign, the color depends on the gas inside the tube (multi-colored “neon” signs aren’t just neon). CO2 laser gas glows purple, so white means there are other gases present which should not be there. The glow has nothing to do with the laser beam itself, which is invisible in the far infrared band.

One of these tubes generally lasts a few thousand hours and costs a few hundred dollars. A failure like this is not unexpected and replacement is just part of the maintenance and upkeep of the machine.

This was my first time replacing a tube on one of these machines and it was easier than expected. Since this OMTech machine is just one of the MANY Chinese laser cutters on the market, the tubes are pretty much interchangeable.

I checked the alignment of everything and didn’t need to realign any mirrors afterwards, though adjustments could be needed in some cases.

After installation, the fresh tube provided a MASSIVE power increase and cutting speeds. I’ve been able to finish up shield production with the new tube, and will have a large batch ready for Ravenwood Faire this weekend!