This Maker Built a Gas-Mixing Device for DIY Laser Tubes

Low-powered lasers, like those around a milliwatt or two, are often solid state devices. Those are the lasers that you find in laser pointers or very weak laser engravers. But more powerful laser cutters require large laser tubes. Those are filled with specific gas mixtures and electricity passes through the tube to produce the laser beam. YouTuber Cranktown City is on a quest to build his own DIY laser tube — a task that very few people are willing to undertake. He needs to fill that laser tube with gases in the proper proportions, which is why he built this Arduino-controlled gas mixing device.

Working with gases is challenging, because you can't simply pour the gas into a measuring cup to get the correct amount. Gas is usually measured by either weight or volume, which Cranktown City was struggling to handle manually. This device lets him pump a known volume of a specific gas into his DIY laser tube, so he can fill the tube with the correct gas mixture. The process starts with evacuating air from the laser tube until it has a decent vacuum, which means that Cranktown City only has to pump whatever gas he requires.

Specific gases, such as nitrogen or CO2, come in storage tanks. This device pumps gas from its storage tank into a special reinforced inflatable bag. Once that bag is full, the device pumps the gas into the laser tube. Each bag is one part of the gas mixture. If Cranktown City needs a 2:1 mixture of nitrogen to CO2, he can pump in four bags of nitrogen and two bags of CO2 — or however much is needed to fill the laser tube. The Arduino controls three relays. The first provides power to the pump, while the latter two open and close input and output valves. A limit switch mounted in front of the gas bag detects when the bag is completely full.

Cranktown City definitely isn't a stranger to metalworking, because he housed the electronic components within a heavy-duty case made from bent and welded plasma-cut steel. He painted that case is a pretty yellow color. It resembles a small welder and looks very professional. Now he can fill his DIY laser tube with exactly the right amount of each gas, which should help him finish that project.