3D Printer Air Compressor Is A Wankel

We wonder if mechanics are as annoyed when we say “engine” as we get when someone talks about a “computer” or a “radio.” Sure, you know what all three of those words mean, but there are many different kinds of radios, computers, and engines. In [3DprintedLife’s] case, he made a compressed air engine of the Wankel style.

The Wankel — a rotary engine — is most famous for its use in some Mazda cars. If you’ve done a lot of 3D printing, you know that creating an air-tight piston on a 3D printer is no mean feat. Of course, he didn’t do it right off the bat. It took what looks like a number of iterations to get it going, and he shares some of what he learned doing this project.

The engine isn’t particularly efficient and you can see it spins for a while and stops, but it is a great demo, especially when he replaces the 3D printed cover with a clear plastic one. Getting the tight tolerances you need can be a real challenge. One thing that helped was printing on a raft so that the bottom of the parts were flat instead of matching the slight tilts in the printing bed.

We were impressed with the two-part design and the 3D printed springs and valves. Even if you don’t want to build a Wankel, you can pick up some tips on creating mechanical parts with filament 3D printers.

This isn’t the first 3D printed Wankel we’ve seen. The technology has its fans and detractors if you can go by the Hackaday comment history.

31 thoughts on “3D Printer Air Compressor Is A Wankel

  1. I guess it’s a bit more more widespread and publicly acceptable of a term if you don’t inadvertently use the letter r instead of the letter l?

    Anyway, mostly not sure if this is another fan or detractor but air pressure inside one of these type of 3D printed objects seems like a very bad idea. Not to even start to be mentioning operation or a broadly good idea or so on.

    1. I’m impressed it works. From my experience repairing a few compressors getting everything sealed properly to make motion out of air (even without compression) is no small challenge.

      I’m not seeing much alarming here. Unless you’re implying that it’d be dangerous to push through an *unrestricted* level of air pressure. Which’d turn commercially constructed devices into shrapnel, too.

    1. Technically it is still an engine! Compressed air is the “fuel” and it is using mechanics (expansion of the gas in the cylinder pushing against the rotor) rather than aerodynamics (which a turbine utilizes) to convert that “fuel” into mechanical energy.

          1. Or just “do something”. Engine was a catch-all term for any mechanical contraption that performs some working action, roughly equivalent to what we would call a “machine”.

            To make the distinction, it needs to have one or more action which is independent of the user, in other words whether the user is merely providing the input energy, as opposed to being directly involved in how the action is performed.

          2. Consider the following: search engine, game engine, physics engine, cotton gin (from “cotton engine”). None of those is heat-powered, nor does any of them except the last deal with mechanical energy.

            Etymologically, an engine is just something that was created through the use of ingenuity (as a device is something that was devised).

      1. Anything with moving parts is an engine according to older usage, cf “war engines” etc, or the engine of a mill might be discussed, basically meaning the drive train from the paddle or sails. Mostly the only ambiguities with that in modern usage you might run into are things like pulse jets and solid fuel rockets, they’re motors, but are they engines?

  2. I dig this, it’s really cool, though it seems overcomplicated by the valves, which are totally superfluous in a Wankel design. Perhaps they’re necessary for running on compressed air rather than actually being an Otto-cycle ICE.

    That said, frankly to most impressive part of this is the rotor-sealing. Mazda had problems with this issue for a LONG time, so for an individual hobbyist to get it mostly-working with 3D printed parts is freaking amazing!

    1. Thank you I appreciate the comments, sealing the rotor was a huge pain! And the valves are purely to improve efficiency. The wankel engine was obviously not designed to run on compressed air, so if I went with a valve-less design, it would be dumping a huge amount of high pressure air out of the exhaust. With no valve to regulate the input, air would just keep flowing in until it begins to vent and the intake port moves on to the next chamber. I have a few thoughts on how to simplify the design and further improve efficiency (still using valves), but I don’t think you’d be able to match that with any compressed-air powered, valve-less design.

    2. Well.. Maybe because this engine stays cool and can use rubber to seal the gaps. The combustion engines heat up and pressure goes up in an instant. Way more difficult to seal well.

  3. I thought the wankel rotary engine was best known for the Monty Python, “Are you easily embarrassed?” sketch.

    Assistant: Shoe, megaphone, grunties.

    Dr Gruber: Now lets go on to something ruder.

    Assistant: Wankle rotary engine.

  4. You know what makes your 3D prints more accurate? Milling it down to size. You’ll have much more luck if you mill the sealing surfaces flat. The chamber is a little harder to do, but still possible.

    1. Hahah come on man that’s cheating! The challenge with this project was to use a technology most hobbyists have (fdm 3d printer) with minimal post-processing. If I’m gonna mill it, I may as well make the whole thing from metal! ;)

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