Orbital – Not your Usual Oscillator!

[JasonBModerator @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 teh 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 conventonal turning tools, form tools for the balls and some freehand graver work for the concave parts.

 

[JasonBModerator @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.

 

[Michael GilliganParticipant @michaelgilligan61133]

Love it !

MichaelG.

[Grindstone CowboyParticipant @grindstonecowboy]

I like that, even though I don’t fully understand how it works!

Rob

[Grizzly bearParticipant @grizzlybear]

Fantastic workmanship.

[Nigel Graham 2Participant @nigelgraham2]

What a wonderful engine!

Lovely work, and very interesting building techniques too.

[Michael GilliganParticipant @michaelgilligan61133]

High Speed drilling machine, anyone ?

MichaelG.

…. I wonder what the original’s intended application was.

[Michael GilliganParticipant @michaelgilligan61133]

Google’s AI image search needed some help, but actually appeared to have learned from my hint:

.

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MichaelG.

[JasonBModerator @jasonb]

Thanks for the comments, even though according to AI it is a Primitive engine.😂

I don’t think there was a specific application, the article that the photo was in featured the models of a German cartoonist, Klaus Kock, better known for his steam powered fish.

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for the copy, Jason

MichaelG.

[John MCParticipant @johnmc39344]

Lovely little engine Jason.  How about a constructional series or some drawings, would make a nice short break from the more “weighty” projects.

[JasonBModerator @jasonb]

I’ve written up several more detailed builds lately that are on this site, some with drawings. Also have one for the recently shown SEL engine that will be going into the mag. All are nice little engines that can be fitted in between longer projects. The new monthly format of the mag means Neil can only run one stationary engine subject at a time so not sure when it will appear as I have one currently running for the Clarkson and then some other articles too.

 

PM me if you ( or anyone else interested in making it) can open .STP files then you can have all the parts and make your own 2D drawings from there for this engine as I don’t tend to make 2D drawings for my own use.

[Jim NicParticipant @jimnic]

A very “different” concept beautifully made as always.

I think I might not try it myself.

Jim

[noel shelleyParticipant @noelshelley55608]

Fascinating in both design and construction. An interesting conversation piece. Thanks for your efforts. Noel.

[Martin Johnson 1Participant @martinjohnson1]

A multi cylinder version would much improve the slow running which would be hypnotic to watch…………

Martin

[Harry WilkesParticipant @harrywilkes58467]

Nice

H

[Andrew CrowParticipant @andrewcrow91475]

Another most unusual design and once again expertly produced, nice job Jason.

Andy

[Martin Johnson 1]

On Martin Johnson 1 Said:

A multi cylinder version would much improve the slow running which would be hypnotic to watch…………

Martin

Here is a quick idea of what a 9-cyl might look like, looking forward to seeing yours running slow😈

[duncan webster 1Participant @duncanwebster1]

Shades of the Gnome Rotary WW1 aero engine

[Mark EasingwoodParticipant @markeasingwood33578]

I like it.

A “stack” of two or three high, on the same pillar, rotating clockwise/anti-clockwise/clockwise, would be an interesting concept. 😈😜

[Howard LewisParticipant @howardlewis46836]

A most interesting engine, very well changed from drawing to hardware.

A two cylinder version should settle any problems with balance.

180 degree opposed, or primary balanced 90 degree to eliminate any secondaries?

Howard

[Howard Lewis]

On Howard Lewis Said:

A most interesting engine, very well changed from drawing to hardware.

A two cylinder version should settle any problems with balance.

180 degree opposed, or primary balanced 90 degree to eliminate any secondaries?

Howard

Sorry to be a Cassandra, but vee twin is not in secondary balance. Straight 6 is, as is a radial.

Might be a definition issue, secondary forces are the result of conrod angularity and vary at twice the rotational speed. For further info see Engineering Dynamics, SAVSwanson page 135 et seq

[Howard LewisParticipant @howardlewis46836]

Duncan, a 90 degree V twin is in secondary balance.

The secondaries act at right angles to the forces produced by the primary balance weights (Hence hammer blow on railtrack from partially primary balanced conventional reciprocating steam locomotives),

Brough always used 90 degree twins. And they were known as the Rolls Royce of motor cycles.

A straight six is not perfect. It is effectively two three cylinders, back to back, where the unbalanced forces from one half are equalled and opposed by the other half, so likely to “wriggle”.

90 Degree V 8s squirm, because the forces from one end of the engine, do not absolutely match the timing of those from the other. (And if a V8 sheds a primary balance weight, you need to be elsewhere before it happens!)

The Lanchester harmonic balancer improved four cylinder in line engines by rotating separate balance weights, in opposite directions,  at twice engine speed.

(We used them on the Rolls Royce C4 and on the Perkins 4.236 family, and on other engines, as well)

Howard

[Howard Lewis]

On Howard Lewis Said:

Duncan, a 90 degree V twin is in secondary  balance…..

If you want to disagree with the likes of Imperial College  thats up to you. Swanson was a lecturer there, I doubt he’s got it wrong.

[duncan webster 1Participant @duncanwebster1]

Here’s a rather poor scan of the relevant page, it does go on a bit…

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