Picture of Cheap and Simple Steam Engine

The Idea:
Recently I saw a video of a remote controlled boat powered by a miniature steam engine  and was instantly hooked on the idea.  After doing a bit of research I found miniature steam engines cost hundreds of dollars or require some very advanced skills and tools to build.  Yet looking at the actual mechanism which allows them to run they are really quite simple so I decided to try and make one on the cheap. 

The point of this project was really to see how cheaply and easily a miniature steam engine could be built. I built this engine in one day and for under $10 in materials so I think it's safe to call it a success.

This engine is 7.2cm (2.8") tall.

Some Things to Note:
First off I should state that this steam engine is only a steam engine.  This instructable does not include instructions on how to build a boiler to produce steam.  Instead I run the steam engine on compressed air.  If you don't have a compressor a bicycle pump works well too, it's just a lot more work for you.  ; )

I should also note that even if you did build a boiler this engine probably wouldn't work well because many of it's major components are wood.  In the presence of steam the wood would swell and warp causing problems.  A simple solution to this problem would be to replace the wood parts with aluminum ones.

I am a very visual teacher so be sure to read the 'Image Notes' (hover your mouse over the yellow boxes on the images), it will likely make my instructions clearer. 

How it Works:
You could read my lengthy description below or you could check out the totally awesome animation by the guys over at www.animatedengines.com, find it here! I should note that this animation is of a "double acting" engine, in that is has ports on both the bottom and the top of the cylinder where mine is a "single acting" engine with ports just on the top.  This just means that the engine relies more heavily on the momentum of the flywheel to keep it running but is a lot simpler to build.

This type of engine is called an Oscillating Steam Engine.  If you watch the video below you will see that the cylinder on this engine actually moves back and forth as the flywheel turns (it oscillates!), this action is what opens and closes the ports which let compressed air enter the engine and exhaust air leave. 

The cylinder has one port at it's top which is pressed up against the main body of the engine.  The main body on the other hand has two ports, one for the compressed air and one for exhaust.  As the cylinder tilts to the right it aligns with the compressed air port allowing air to flow into the cylinder and push down the piston.  This causes the crankshaft to turn, thus tilting the cylinder over to the left and allowing the air to exit the cylinder though the exhaust port as the piston comes back up.  Then the process repeats. 

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Teco242 years ago
Hi there. Thank you for putting this amazing "how to" guide on the internet. I am still in school and was struggling to find a project. I came across and knew this was the one! I appreciate all your time and effort put into making this work. My project turned out real good! Thank you once again :) Teco

Anyone know if this can pull any weight? I'm thinking of making a ride-able train for my niece and nephew; and I want to model it after the steam trains used in Walt Disney's Worlds' Magic Kingdom.

Raccoon772 days ago

You could use the tea light tin as a mold to cast a lead flywheel. Lead is really easy to melt and cast.

T0BY1 month ago
Excellent! Well done!
Tristan Hart 3 months ago
Hi, please fix your measurements, I'm from RSA, and where you said mm, we used millimetres, please make them RSA friendly plans
WOLFskull054 months ago
would pvc
work too

Do you think you could use a Dremel to cut it?

liam2317 (author)  mirnes.neziric9 months ago

A Dremel would probably work fine, just be sure to take your time with it. You don't want to push too hard and deform the metal, it's very important that the cylinder and piston stay as perfectly round as possible.

Sir so the system can only run by the air compressor if i use steam air sir is it possible sir thanks the response
liam2317 (author)  mark1112137 months ago

As mentioned in the instructions, you could probably run it with steam
just fine. The only concern is that the wood might become wet and swell
in size so you should likely either not use wood or find a way to make
the wood waterproof if you are going to use steam.

kikid1128 months ago
Hey guys , i found this cylinder and piston from 12v air compressor , so can anyone tell me is it possible to make a steam engine with this

Curious mate. What pressure are you putting through the pipe and would you have a clue as to how fast the crankshaft is spinning?

lrawat1 year ago
Aditya M1 year ago


Dowaine1 year ago
how do you oscillate the air
patrickpow2 years ago
Will it matter if the copper tubes are bigger diameter and height wise than those you showed.
liam2317 (author)  patrickpow2 years ago
I actually used brass tubing for this little engine, I bet copper will work fine too though so long as they fit together very closely and still move freely. The diameter really shouldn't matter much (within reason) so long as there is still a very close fit between the two. Height wise; unless you scale the other parts you will run into problems. Just make everything bigger to match the scale of your tubes and everything should work great.
Kevin123452 years ago
Digging in my old broken VCR i found the video head and the first thing that popped into my head was "flywheel". just a thought..
nice one .....:-)
Umm I Know this is kind of late to ask but the last steps you wrote but there are no pictures. I think you probably did that because you were already done. But I don't quite understand how the final assembly goes together. Could you please add one or two more pictures just to clear up. Thanks
lost20104 years ago
How is this a steam engine if you are using compressed air? this is a waste because its pointless to use a machine to run another machiine.
it uses the same principles as an oscilating steam engine so hence technically it is but as the maker said, a lot of parts are wood so if you want a genuine steam engine use metal.
it uses the same principles as an oscilating steam engine so hence technically it is but as the maker said, a lot of parts are wood so if you want a genuine steam engine use metal.
This is a steam engine, If you built a small boiler and everything to go with it it would run it just as well as the compressed air. But homemade boilers are risky and dangerous if you're not experienced. So using a air compressor is safer and easier (And cheaper)
but not as cool besides the boilers don't generally burst like a frag, their seams split and vent steam. sorry if you wanted shrapnel but chances are you'd just get burned.
MIRAMANALI3 years ago
hi this project looks really cool i am planning to use the basics to make one for a geared bicycle so that i can use its gears as helping hand for the engine(reducing the load). instead of a single acting engine i want to make a double acting engine but am confused whether adding one more inlet and outlet as above hole on bottom side of the plank will do the job? ,sealing the cylinder from bottom of course with the valve u have shown above and running the piston rod through the plank of that valve (the hole will be lined inside with rubber just to prevent air leaks because of piston rod)
egustys3 years ago
Best way using propseivers (last foto)
you could also use a hacksaw but that might be abit more trikey and not get such a good finish
akidrick4 years ago
how did you cut the ply wood
cut the ply with a saw. cut roughly around where you need to cut. make sure you have drawn out the patten onto the wood exactly right then make a waste line and the exact line cut in the middle of the waste line and the exact line when this is done sand it down till it is perfect. make sure you don't go over the exact line or you will need to start over. it would be good if you used a small saw unless you are very careful. you could also use a copping saw or jigsaw but that might be abit more tricky
sam D4 years ago
Love this build. White nylon cutting boards from the junk shop - which are high density PE might be an alternative for the wood. Low friction, good durability and high temp resistance.
I'm thinking about building a steam powered boat. And I like the idea of this steam engine but my idea of a engine is where there is olive oil burning boiling 2 quarts of water. when the steam becomes pressurized it will be pushed out of a two way valve so it creats pressure to push boat. But this engine has to carry a model boat, car battery, live camer, antena for radio control, ROV (which has camera on it), 200ft cable to power ROV, 200ft cable to carry information from ROV camera to model boat. Which engine would be better the one I thought about or the one liam2317 made?
liam2317 (author)  planetroverrobo4 years ago
Sounds like a pretty complex project already, may as well save yourself the trouble and just go electric. You would need a pretty big steam engine to move around all the things you listed at a decent speed. Unless you have a very specific reason for using a steam engine I would definitely just use an electric motor if I were you.
ok thanks. I'v decided to go electric any ways also I'v decided to take everything of what I listed. Instead I made a pontoon boat puting 4 D cells or C cells and a small solar panel to rechage batteries. Thanks anyways though
Sky Woulf4 years ago
if using seeam (bolier problems aside) you could use an old model airplane trick..... in a gas powered model airplane we coat our "wood" engine compartment and fuel tank compartment and the firewall with painted on 30 min epoxy (find it at your local automotive parts store) and this completely seals the wood from "Any" moisture, solvents, etc. (also has high temp restance somewhere around 1300 degrees F i think) so if you were to coad ALL surfaces of your wood like that you could (I think) run low presure setam in this motor. then you could try to run it off a stovetop tea kettle with a stopper and a hose. just allow for the pressure to build before starting!
liam2317 (author)  Sky Woulf4 years ago
I think this would probably work quite well. If someone does try this I would definitely recommend coating the parts with epoxy either before, or as you assemble them (you could even use the epoxy coating to glue the parts together as well as seal them!).
sbinc0284 years ago
what's the spring for?
liam2317 (author)  sbinc0284 years ago
The spring is used to push the cylinder head piece up against the main body piece to provide a good tight seal between the two. In the pictures though, you can see I replaced the spring with a small elastic band that goes around the whole steam engine. The elastic seemed to work a lot more efficiently than the spring did.
flowerman74 years ago
Nice project! for the piston could you cast it out of J-B weld like many people do when building stirling engines. How airtight doues the pison and cylinder actualy have to be? Thanks
liam2317 (author)  flowerman74 years ago
I tried casting a piston out of epoxy as well but found that the brass tubes fit much better, were much easier to make, and seemed to have a lot less friction. My guess would be that it would still run if it leaked a bit but the more air tight the better!
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