DIY Stirling engine from a tuna can
Posted by Harmjan H. on Apr 6, 2011
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| 6 comments

DIY Stirling engine from a tuna can

DIY Stirling engine from a tuna can

I am currently working on my third engine, after my 1st and 2nd attempts failed miserably… I thought my third engine would run. I thought wrong. It was airtight, it turned smoothly but it seemed that the piston didn’t had strength enough to turn the cranks. Maybe I made the piston too big for the small tuna can? So there is little air to lift the balloon?

If somebody knows the answer, let me know. For know I am going to try and find a smaller cylinder for my piston.

diy stirling engine can

…maybe I have some reading to do about piston sizes

…and maybe it wasn’t so airtight after all. It got condensation in the cylinder of the displacer, so that’s not good. Back to the drawing board! Maybe someday I’ll have one running like this solar one or this solar powered lamina flow engine.

Buy a paper stirling engine

If you want to learn the basics of a stirling engine but unfortunately you have -like me- two left hands, you can always buy a cheap low-temperature engine. Maybe this incredible cheap but working! cardboard engine on eBay



6 Responses to “DIY Stirling engine from a tuna can”

  1. Michael Couch says:

    You can order a Cardboard Walking Beam Stirling on Ebay for $10 U.S. another $7 for postage from the UK. I got mine working last night. I cut mine out of platic. It is like a murder mystery to figure out just what keeps it from working, until you have all the issues solved. You must eliminate all friction.
    This Walking Beam Cardboard Stirling is nice to work with because it has built in adjustments. I cut one of shafts too short but was able to compensate by changing curved section at the top to make it longer.
    I also redid the balloon diaphram But I’m not sure if that was necessary to get it working. The original used the Tit shape of a balloon. I modified it to use the flatter part.
    Right now with only one Tea Candle burning it only runs until the water is heated such that the temperature differential is too low to run.
    However, I am making two wick T-Candles which run much stronger and longer.
    It is apparent that this design needs to be modified to take more heat away from the cold side. Then it should run as long as the flame is high enough under it.
    It is a delicate ballancing act to get it running. Keep everything as adjustable as possible. There must be NO AIR LEAKS except a very tiny one where the fishing line leaves the can. Be sure to sear around the top of the can too.

    Michael

    • Michael Couch says:

      Forgot to mention that one source of friction on the Cardboard Walking Beam Stirling that was hard to identify was where the rod shafts go through the connector on the wheel Axel. It was only rubbing when it was horizontal inward due to a slight bend there.

      The solution was to cut this rod shaft so it does not go past the axel shaft.
      I cut it too short and had to re-bend the upper part of the shaft to get more length.

      Also, use the string to test the balloon while a candle is under the can lit. This will allow you to see how it is supposed to work.

      The balloon gets filled when the displacer piston is at the top of its stroke. When the displacer in the can is at the bottom the balloon is sucking in.

      The axel cam is at its bottom position when the displacer is at the top of the can. Also, the wheel must be connected to perform its flywheel function to keep it running. If the wheel is free turning instead of attached to the axel, it wont run. I had to bend the axel end up and tape my wheel to get it to grab and turn the axel with flywheel action to complete the cycles.

      One more thing, if the string is not exactly right one of two things happen…
      1. The displacer pulls back because it is hitting the can top, stopping the machine.

      2. The displacer isn’t going high enough and sits on the bottom too long, minimizing the power stroke of the balloon, making it not strong enough to function.

      Oh, also, more candle flames 2 instead of one for instance will help. I created my own two wick candles to help with this but you can also position two tea candles under the can to help.

      • Windu Hernowo says:

        Shame to say, that I had the same experience. I had thesingle can tha I believed there was no air leak. But still, te air didnot fill the top rubber. Guess the esult : no rotation can be made by the engine…….

  2. sniffles says:

    i’m in love. you fail so elegantly, gallantly, humbly. i wish i could meet a man like that. the last one i heard of was a.t.edison who didn’t so much fail but “found 200 (or was is 2000?) ways NOT to make a light bulb”.

    i envy your wife and am ecstatic for your children.

  3. Peter Nortje says:

    Hi – never give up – here is the URL to my 4th attempt !! and final success – check it out

    http://www.youtube.com/channel/UCJvaJntAKlC_XvNn_e14FoA

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