When I saw the topic of engines,

I realized that there is no model anywhere, including here in MAKER WORLD, that simulates the mechanics of a real engine.

What the heck am I talking about???

All internal combustion engines (except rotary engines) have a mechanism that uses the force of the fuel explosion to create reciprocating motion of the piston and convert that force into rotational motion.

However, all the 3D printed engine models I've seen reverse this transfer of force, using rotational motion to create piston motion, as shown in the video below (which is also possible in my model).
Of course, you can still understand the motion of the engine in this way, but you can only imagine how the energy is actually transferred.

My model simulates the energy transfer process of a real engine.

Of course, the initial energy, the “explosion”, has to be done with the fingers.

The model is a three-cylinder engine, so the direction of rotation can be changed by the order of pressing.

This model “perfectly” simulates the internal combustion engine and allows you (or your kids) to understand it.

After making this, I realized how fast the explosion of a real engine is... The highest speed I can make is around 150 rpm :)

Maybe you're asking  “What's the big difference?”, and I wasn't sure either until I tried to make this.
But go ahead and print it out. You'll definitely have a different experience.

The body which includes most of the parts is in-place print. And the connecting rods and the propeller are printed separately, but super easy to assemble.  

It was possible to make all of them in-place (I've done this at my first try), but it made the connecting rods easy to be broken. so…

Below is my first in-place printed concept model 

Remove the support part after print.

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Here is a unique arcade game using this engine.

[https://makerworld.com/ko/models/1580699-f1-dragracing-finger-powered-engine-drive#profileId-1663547](https://makerworld.com/ko/models/1580699-f1-dragracing-finger-powered-engine-drive#profileId-1663547)