[Lucas] is busy in Cranktown City on YouTube recently, but despite showing up, his latest project is not a welder. Instead, he built a very smart gas mixer to fill his own homemade CO2 laser tube, which looks like a welding machine. (Video, embedded below.)
We have been following the process of [Lucas] making the laser cutting machine from scratch-actually starting from scratch, because he made his own laser tube instead of relying on something off-the-shelf. However, due to the use of the correct mixture to fill the test tube, it was a bit painful because he used a party balloon to collect carbon dioxide, helium and nitrogen. After each addition, he measured the diameter of the balloon to determine the proportion of each volume. His attempts to automate the process revolved around the so-called AirShim, which are basically flat inflatable bags made of sturdy material that contractors use to pry, wedge, lift, and fill gaskets with air pressure.
[Lucas]’s first idea was to use water and the displacement of some photoelectric sensors to measure the amount of gas in the bag, but this proved to be impractical and unnecessary. It turns out that when filling the bag with a simple micro switch, it feels much easier. The amount of gas generated by each type of filling is fixed, so it is easy to figure out the distribution amount of each gas. The Arduino controls the pump, which is a recycled refrigerator compressor, monitors limit switches and controls solenoid valves, and calculates the amount of gas dispensed.
From the video below, the mixer works well and we are impressed by its simplicity. We have never seriously considered making our own laser tube before, but seeing [Lucas] can make it look quite approachable. We look forward to watching his laser project.
Cool ideas and equipment. However, it seems that the work of changing bottles many times is very necessary. Why not add a solenoid to each bottle and automatically complete the mixing.
I think it depends on how often you fill the tube. Is it worth buying a valve and creating more control channels for the things you do occasionally? This is something we geeks often make mistakes.
The same question, is it worth spending time designing and building a more complex system with more features than you need, and the precious spare time you want to spend is not building tools, but building lasers.
Also, I know this is not in line with the work done here. But people can buy pre-mixed CO2 laser gas in the best ratio.
Those who are interested in this idea can obtain multi-channel air valve blocks from the aftermarket automotive air suspension industry.
The easiest option is to get three needle valves and a flow meter. This is how most people and companies handle their mixture because it is a constant flow rate. It’s not like you can charge the tube and let it run, there is no catalyst to keep carbon dioxide, carbon dioxide.
In addition, the refrigeration compressor circulates oil through the system, so there will be a ton of oil vapor in the gas, which is a very bad thing.
This guy only needs to doodle to eBay and buy used MFC valves from the semiconductor industry. You can usually find 200 sccm mks for $200.
The best of Macgyver! If you can’t get the parts, you can build it, or like I did indeed use the springboard parts and the slanted references in the open source code to invent this technology from scratch. Now, if I can repair my two-stage pump.
It looks like the air-filled bag is completely emptied after each filling, or is it? When the pressure in the main fuel tank becomes higher, is there still some gas remaining in the air gasket bag (the pressure balance between the bag and the yellow fuel tank)? If so, is there some kind of mixed gas, so any residual gas in the air gasket is a mixed gas? When the “fill” valve is opened, it will also mix with the gas in the main bottle so that over time, will the gas in the bottle be contaminated by other gases? (Maybe the air gasket bag is emptied between each fill/empty cycle?).
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