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This Tiny Steam Engine Takes A Watchmaker’s Skill To Build | Hackaday

When your steam engine build requires multiple microscopes, including those of the scanning electron variety, you know you’re building something really, really tiny.

All of the usual tiny superlatives and comparisons apply to [Chronova Engineering]’s latest effort — fits on a pencil eraser, don’t sneeze while you’re working on it or you’ll never find it. If we were to put the footprint of this engine into SMD context, we’d say it’s around a 2010 or so. As one would expect, the design is minimalistic, with no room for traditional bearings or valves. The piston and connecting rod are one piece, meaning the cylinder must pivot, which provides a clever way of switching between intake and exhaust. Tiny crankshaft, tiny flywheel. Everything you’d associate with a steam engine is there, but just barely.

The tooling needed to accomplish this feat is pretty impressive too. [Chronova] are no strangers to precision work, but this is a step beyond. Almost everything was done on a watchmaker’s lathe with a milling attachment and a microscope assist. For the main body of the engine, a pantograph engraving machine was enlisted to scale a 3D printed template down tenfold. Drill bits in the 0.3 mm range didn’t fare too well against annealed tool steel, which is where the scanning electron microscope came into play. It revealed brittle fractures in the carbide tool, which prompted a dive down the rabbit hole of micro-machining and a switch to high-speed steel tooling.

It all worked in the end, enough so that the engine managed 42,000 RPM on a test with compressed air. We eagerly await the equally tiny boiler for a live steam test.

I wonder how many times he dropped it and had to start from the beginning.

@Andrzej said: “I wonder how many times he dropped it and had to start from the beginning.”

I wonder how many times he dropped it and couldn’t find it again.

I took his joke to be that when he dropped it, he couldn’t find it and thus had to start over.

I still can’t find all of microSD I’ve dropped and those are much bigger than the steam engine. Heck, I’m still finding tiny LEGO pieces I lost 40 years ago.

I wonder how many times he dropped it and simply picked it back up again.

Incredible skill, and a compelling video. Props.

Run a tiny generator with it to build a steam powered watch! Maybe a low boiling point liquid to run it with the heat of your body?

I wonder if a teeny Stirling engine could be made with this technique… That could have some applications somewhere a power supply is needed that runs off temperature gradient alone, and is extremely small

Though I won’t claim this sort of tiny is impossible in Stirling it seems very very unlikely.

As unless you are discounting the hot/cold heat exchange surfaces and air displacement piston you will really struggle to get a Stirling engine anywhere near this small to work – the pressure that will be required to overcome all the friction and inertia means you’d need a very high heat differential between the hot and cold sides. And when something that small is really hot on one side its likely to manage to get very close to heat saturation on the other as actually keep the cold side cold would be challenging.

And if you take that hot/cold cycling part out of the ‘really tiny’ then you barely need to change this ‘steam’ engine to be the power stroke of a Stirling engine – just replace the input and exhaust with a single pressure inlet the piston pivots around instead (though if such a tiny piston can manage to move a large enough air displacement piston I do somewhat doubt).

I’d think if you really want tiny and power generation in this case I think the Peltier style element is about the only very functional option, though a variation on the operating theme of a Stiriling engine – the thermoacoutisic might scale down well enough, but it isn’t nearly as satisfying to make or watch. Though size a Stirling up a little from absurdly small to just desktop paperweight small and a Stirling engine becomes much more plausible.

I believe it was James Senft as seen in Live Steam magazine from likkkeeeee the 80’s that built a tiny engine that used a thimble for the boiler. It is also in Steam and Stirling Engines You Can Build book

I wish my hands were this steady.

Username checks out.

@shaker said: “I wish my hands were this steady.”

I say: “They are. Speaking from experience, all it takes is a couple of long pulls on the vodka bottle.” ;-)

Does that really work? I don’t drink alcohol.

I have a little bit of a claustrophobia issue when I have to have an MRI. The tech at the MRI place recommended that I stop at the bar just down the street for a beer before I come in for an MRI. I went with a pharmaceutical option, which also precluded me from driving for a while after the imaging.

It depends, but possibly. I have a condition called “essential tremors”, thankfully mild and doesn’t interfere with my day to day really. But for fine motor skills like soldering SMD parts, my hands shake too much. A shot of alcohol steadies my hands perfectly though. Beta blockers are the pharmaceutical option I was recommended, but there may be other treatments now.

Sherline Machine Tool used to have a yearly contest of who could make the most powerful engine that fit in a one cubic inch space, and I thought that was a really cool project. I’m sorry they don’t do it anymore.

What’s their definition of “engine?” Could one submit a cubic inch of HMX and specify that it will create power for a few milliseconds only once? That sounds like a really fun contest jokes aside, they should reboot it

That contest is so hidden/exclusive that your comment shows as first when searching on google for “sherline cubic inch engine”.

It was quite a while back that they stopped running this, like 2005, maybe. It was called the Sherline Machinist’s Challenge. It was part of the North American Model Engineering Society convention.

What is this? A steam engine for ants?! Very fascinating build.

Just had a thought. Since it takes some time setting things up to cut and shape these parts, and since there’s such minuscule amounts of material being used here, I would consider making multiples of each part in a project like this. In case you drill a hole incorrectly, or bend a rod.

Model Engineering, like homebuilt aircraft, holds that you make the model twice, the one you throw away because you messed up something, and the second one that came out right after you messed the first one up.

I saw a very similar device at the south west Minnesota steam threshers reunion years ago. It’s a must see if you like steam.

42kRPM that’s getting the dental drill range singing at the top note of a piano.

Funnily dental drills often also work on compressed air – they just use turbines instead of piston engines :)

Good thing they don’t use actual steam!

Is it just me, or is this “steam engine” missing the steam part? Quite a nice feat of machining though…

Two geeky thoughts: What are the resonance effects and could they be maximized (could you make it run even better with a specific cantilever mount and unbalanced flywheel)? Also at what point does the scale of the gas used begin to interfere with the operation of the engine? Compressed air and (very dry) steam are reasonably close but a single drop of liquid water could stop this thing, er, cold. Would you have an engine that could run on air but not on (for instance) gaseous R-134a?

I would’ve loved to see it run on steam.

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