When people ask me what I do at work on any given day, it’s not uncommon for me to smirk and say things like, “We purposefully exploded a pop bottle to launch thousands of ping pong balls in the air.”
“I guided our guests through building and launching model rockets a few hundred meters in the sky. Recently, I had another smirk on my face, because I cut some wood, not with a saw, but with a laser!"
In the Science Garage workshop, we have many exciting tools at our disposal including a laser cutter! Our model is a 40-watt, water-cooled, carbon dioxide (CO2) laser cutter. This machine allows us to cut or engrave computer generated graphics on a variety of materials by running an electrical current through a sealed tube of CO2 gas. When the current flows through the gas, it generates a great amount of energy that the machine then focuses through a combination of lenses and mirrors. The laser energy is focused in such a way that it can precisely burn the wood (or other laser safe materials) ...most of the time.
As my engineer friend always says, “...there are a finite number of cycles until failure of any machine, simple or complex.”. In other words, everything will break at some point. It could take seconds, days, or even centuries. Whether it is a rubber band, door knob, toaster, everything will fail at some point. On a day in October, just prior to beginning to cut some of our spider lamp templates, the laser began to lose power. The tube was burned out and needed replacing. Laser fail.
It was time to replace the laser tube. I gathered the materials necessary and removed the old tube and install the new one. It’s simple when one reads the tube replacement instructions, but once I started, it became clear that it involved a great deal of care and attention, and there was plenty of room for error.
The tube is made of glass, so I needed to be careful I didn’t bump it and break it. The tube is also filled with water, so I needed to be sure to have plenty of towels on hand to soak up any drips when the water-cooling hoses were removed (we all know that electricity and water can be a dangerous combination). To add to those two, the power leads are sealed on with silicone due to the high voltage.
Installing the new tube took about 45 minutes or so to ensure all hoses, cables and brackets were connected properly. The next step...test fire the laser! With a little adjusting of the mirrors, the laser was fully operational again. The new tube should be good for a few thousand hours of cutting time.
I tested the laser on some 1/8" plywood as well as some cardstock and everything looked great. The laser tube had been successfully replaced and the machine was successfully harnessing the 40-watts of power coming from the CO2 laser once again! Check out some of the footage of the first test cuts with the new laser tube in the video below. Keep an eye on the plasma glowing in the laser tube!