I’ve been working on Jan Ridders’ “Flame Eater” engine for over a year now. When I first started I didn’t have a mill (nor a plan as to how I would complete the project without a mill) but I started on the engine anyway. Eventually I turned just about every piece that could be turned and then hit a wall. Without a mill I could go no further. So the project got shelved for months while I searched for, purchased, and restored and Atlas MFC mill. A few weeks ago I finished my mill restoration and it was time to get back to my little Flame Eater.

Many of the pieces for this engine are easy to machine and require no explanation, but some are a bit more difficult. My intention here is to describe the more complicated pieces and the machining steps I used to complete them. My methods aren’t the only way to machine the engine, but if they worked for me, they should work for you as well. I’ll be documenting this project in several parts:

Part 1: The Cylinder
Part 2: The Piston, Valve, and Connecting Rod
Part 3: The Flywheel
Part 4: The Ball Bearing Support and Spirit Burner

So let’s get on with it.

Part 1: The Cylinder

Jan recommends using “pearlitic cast iron” or stainless steel for the cylinder, piston, and valve. I’d recommend trying to get cast iron if you’ve never worked with it before. It’s different than steel and very messy to turn, but I think that it’s properties lend itself well to the cylinder design. For one thing making the cylinder, piston, and valve from cast iron helps with lubrication because cast iron rubbing against cast iron is somewhat self-lubricating. With a flame eater engine you don’t want to use oil to lubricate the cylinder because it will eventually burn away and gum up the cylinder. Another benefit of cast iron is the fact that it was easy to cut the fins with a parting tool. The cast iron chips were short and broke away easily unlike steel, which often produces long springy chips that bind in between the two halves of the piece being parted off (or in this case between the fins).  In my opinion it would have been a little more difficult and taken more time to cut the fins in a steel cylinder. Whichever you choose, be sure to make all three parts out of the same material. If you make the valve and piston out of steel and the cylinder out of cast iron (or vice versa) they won’t expand and contract at the same rate leading to either a sloppy fit, or too tight a fit once the engine heats up during use.

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This is the third and final engine contributed by Jan Ridders of the Netherlands, a pressure controlled 2-stroke engine.

I asked Jan to pick his most simple designs in each of 3 categories, Stirling, Flame Eater, and IC.  This set of plans is for his most simple IC design, a pressure controlled 2-stroke engine. If you’d like to see the other two designs shared by Jan, they can be found here: Jan’s Coffee Cup Stirling Engine and Jan’s Flame Sucker. And of course, all of Jan’s other engines can be found by visiting his site, which is written in both English and Dutch.

Here’s an animation and a description of the principle behind Jan’s masterpiece (excerpt from Jan’s site):

A ball valve only opens when the pressure below the ball is higher then above the ball. For the upper valve this is only the case, and for a very short time, when the piston reaches the exhaust port. The pressed gas mix below the piston and between the two ball valves is injected then, filling the cylinder and pushing out the remaining burned gases. Before and shortly after that moment the pressure above the ball in the upper valve is always higher then below the ball. When the piston is moving upwards there is an overpressure above the ball (gas mix compression) and a lower atmospheric pressure  of the sucked-in fresh gas mix below the ball. When the piston is moving downwards there is a high overpressure above the ball due to the combustion (power stroke) and a much lower overpressure of the compressed fresh gas mix below the ball. So also during that power stroke the upper ball valve keeps closed until the piston opens the exhaust port.

So the timing of the process is exactly right and automatically controlled by the alternating pressures in the system. That is why I called this engine the “Pressure controlled Two-stroke”.

Here’s a video of the engine in action:

For more information on this engine (including construction tips and trouble shooting) please visit Jan’s website. Jan also has many other engines on his site and he shares his plans freely with anyone by request.

I’d like to say Thank You one more time to Jan Ridders for sharing multiple sets of plans with this site. By sharing your plans you’ve helped this site grow.

  Pressure_Controlled_2-Stroke_Engine_-_Jan_Ridders.pdf (5.1 MiB, 1,418 hits)
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[nms: stirling engine]

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Material: Aluminum, Steel, and Brass
Units: (in)

If you’re looking for a simple engine to build that runs on compressed air, here’s a nice set of plans for you. Here’s what Rob had to say about his plans:

“This was the semester long project we did in class for Machine Tool Technology at the University of Central Missouri . I would like to hook the engine up to something and do tests.

The base is made out of a 3/4 in thick aluminum and the body and cylinder is mild steel. The flywheel and crank is made out of brass. I used most tools that you would use with metals. Vertical mill, horizontal mill, metal lathe, drill press and grinding machine, thread tap. I even machined the threads on the wrist pin.”

- Rob K.

Here’s a video of the little engine in action:

Thanks for sharing your plans Rob!

  Air_Engine.pdf (1.1 MiB, 1,306 hits)
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