Cams and Pushrods Improve 3D-Printed Compressed Air Engine

Some folks just can’t leave well enough alone, and that often ends up being a good thing. Such is the case with this 3D-printed compressed air engine, which just keeps getting better.

The design has changed a lot since we first covered [Tom Stanton]’s attempts at reviving the powerplant from the glory days of the Air Hogs line of toys, which he subsequently built a plane around. The engine was simple, with a ball valve that admitted air into the cylinder when a spring mounted to the top of the piston popped it out of the way. That spring has always bothered [Tom], though, compelling him to go back to the drawing board. He wanted to replace the ball valve with one actuated by a cam and pushrod. This would increase the complexity of the engine quite a bit, but with the benefit of eliminating the fail point of the spring. With a few iterations in the design, he was able to relocate the ball valve, add a cam to the crankshaft, and use a pushrod to open the valve. The new design works much better than the previous version, sounding more like a lawnmower than a 3D-printed engine should. Check out the design process and some tests in the video below.

And speaking of lawnmowers that run on compressed air

Thanks to [Baruch Even] for the tip.

11 thoughts on “Cams and Pushrods Improve 3D-Printed Compressed Air Engine

  1. Lovely work with some nice analysis of options.

    Buuuuut, (as with the previous post on this gent’s work) I would love to see comparing total thrust of a laminar flow air jet valve to the total thrust of this air-driven engine. Seems to me a lot of the energy is lost to friction and gaps and whatnot. I’ll take an uneducated guess of around 30% efficiency?

    1. I agree with you that the efficiency will be lower; though, I wonder if this engine has better performance for his application. Maybe the total thrust of a laminar flow air jet will be greater but will occur over a much shorter period of time. Sure, it may be possible to optimize a nozzle to fix that issue, but the most laypeople won’t know how to do that.

  2. I *really* enjoyed the first video and the second video. The weather is also just starting to get nice out and I just got the 3D printer fired up again for couple of projects around here and I thought it would be cool to try and build one of these. I looked for the files, and I found this comment in the first video: STL files are available to my Patreon supporters

    Now this is looking a lot more like a commercial project and he got his 15 minutes of fame with the first video. Perhaps HAD could showcase some neat things from people who are actually willing to share what they do and not sell it.

    1. A pledge of $1, which you can cancel immediately after making, to get access. The instructions come with no use terms at all other than it is at your own risk. Is that too much to ask?

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