Engines > Your Own Design

Orbital - Not Your Usual Oscillator

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Jasonb:
For some time I have fancied making an engine with a horizontal flywheel but never found anything that took my fancy. There is an old design for a marine engine that was tempting but not the nicest looking thing. Anthony Mount did the Whitmoore & Binyon but you can't really see the flywheel on that. Howeve while looking through some old copies of Dampf Modell magazine for something else, this photo caught my eye and that was all it took.



A bit of time spent with Alibre and I came up with this design. It is 11mm bore x 13mm stroke. Flywheel is 115mm dia x 6.75mm wide (to suit the offcut of thick wall tube I had) Alibre has the option to show the ctr of mass and by looking at this while trying a few different ball bearing diameters I got the design almost perfectly balanced, it does change as the engine rotates and the piston moves in & out.



The "spokes" were cut on the CNC from a disc of 4mm thick steel and then the various steam passages added on the manual mill. Here I am using a long series drill to get air from the hub to the cylinder.



Some further milling diverted the air around the cylinder pivot which had a bronze insert fitted. The hub was made up of two pieces of brass and the rim from the above mentioned offcut of thick wall tube. All assembled with JBWeld and then finish machined.



A 2mm drill shank was ground to make a cutter to form an annular groove in the bottom face of the flywheel which allowed air to flow from a hole in the base during the full rotation of the flywheel.



The cylinder was much the same as the other small oscillators I have been making recently which start a sa rectangular block that is bored & turned



Then the holes added and port face milled to width



I also milled some decorative flutes with a 2mm ball nose cutter.



The last job was a quick lap with 600g silicon carbide powder and oil mix



The base boss like the cylinder end cover and crank pin cap were turned with a mix of conventional turning tools, form tools for the balls and some freehand graver work for the concave parts.

Jasonb:
I used some VHT wrinkle finish paint for the "cast" surfaces altough it did not wrinkle as well as it has done in the past. The Cylinder was done with Fial "orange red" and the rest left bare.

An offcut of Paranna pine provided the base which was finished off with three ebony bun feet.








Alibre seems to have got it right as there is very little tendency for the engine to want to start dancing around the bench. However it is very much a "stationary" engine as once running all that work becomes a bit of a blur, even the slowmo at the end of the video does not capture it very well.

http://www.youtube.com/watch?v=6sGIH-jBQ-k

crueby:
Unique!  Very cool.

Sanjay F:
Wow - that's so different and quite a marvel to watch. It reminds me of the helicopter toy where you pull the cord and the circular disc takes off!  ;)

I remember we spoke about the Whitmore & Binyon engine some time ago and you mentioned it was a shame the flywheel was covered. Now that I have seen your wonderful creation I couldn't agree more!

Jasonb:
Now there's an idea. Alter the spokes to be more like fan blades, join four engines together and I'd have a steam powered drone :LittleDevil:

But that will have to wait, I've a couple of poor castings to work my magic on to get them looking like a half decent model. Where ehave we heard that before   :LittleDevil: But at least at the end of this major rework I will have the full set of three ;)

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