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Thread: Double acting Double cylinder Oscillator

  1. #1
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    Mar 2008
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    Barrie, Ontario, Canada
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    Default Double acting Double cylinder Oscillator

    This is an engine which has always interested me. I think I first seen an engine like this posted by Tel from Australia. I was bored today, so I thought I would begin sussing out a design for one, built from bar stock. The one in this post has 1" bore cylinders with a 1.732" stroke. The flywheel is almost 4" in diameter (I am still trying to find a way to use those two steel rings I made up for the Kerzel. They didn't work out on the Kerzel, but they may do fine here.) Stay tuned, and as the design develops I will posted updated models.
    Brian Rupnow

  2. #2
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    Another 4 hours and we go from concept to an animation of the finished engine. I decided that a 4" flywheel was small enough that it looked out of place, so I bumped it up to 6" diameter.
    https://www.youtube.com/watch?v=FUln...ature=youtu.be
    Last edited by brian Rupnow; 05-24-2018 at 11:56 AM.
    Brian Rupnow

  3. #3
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    Dec 2008
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    Kendal, On
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    Default

    Interesting looking.

    Looking forward to seeing it run in a couple days

  4. #4
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    If I make the spacer transparent, you can see the 1/4" diameter pivot that is attached to the cylinder and passes thru a 1/4" hole in the angle. A stiff little compression spring and a 1/4" nylock nut ensures that the "face" of the cylinder body is held tightly against the face of the angle to avoid pressure loss, but still lets the cylinder pivot.
    Brian Rupnow

  5. #5
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    If this was going to be a real "working engine" I would make the cylinders from cast iron or bronze, and make the angle from cast iron as well, because of the high wear factor at the point where the cylinder face pivots against the angle. Since it will only ever live as a "demonstration" engine, the cylinders and pistons will still be made from cast iron, but the angle will be 6061 aluminum. The green colored end caps will probably be made from brass for a bit of contrast. The flywheel is massive enough that I am considering making it from solid aluminum.
    Brian Rupnow

  6. #6
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    Apr 2005
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    You could also put in bronze or rolled brass facing plates to improve the wear resistance of the aluminum angle plates.

  7. #7
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    Dec 2015
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    Chilliwack, BC, Canada
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    Quote Originally Posted by bob_s View Post
    You could also put in bronze or rolled brass facing plates to improve the wear resistance of the aluminum angle plates.
    Or even drill oversize in the angle stock body and make up brass "top hat" shaped inserts with the proper size air holes? That way the cylinders run against the raised brass surfaces. They would fit into the body and a touch of CA would bond and seal them. Then a light facing off to ensure the faces are flat and planar. Being round these would be easy to make.

  8. #8
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    The angles are full of air passages, which would make it difficult to lay in any kind of bronze insert in the face of the angles. I'm not overly concerned about it. I have a couple of early "wobblers" that I built about 10 years ago where the cylinders were bronze and the main body was 6061 aluminum, and they don't have any galling nor severe wear patterns where the cylinders rock. Truth be told, these engines might see two hours running time in total, then they go "up on the shelf" and may never be ran again. Thanks for stopping by and leaving a comment.---Brian
    Brian Rupnow

  9. #9
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    I've just been publicly whipped by someone on another forum. I had suggested that the engine would run "smoother" with better balance if the crankshaft was set up for 180 degrees. I was wrong. With the crank throws at 180 degrees, you only get a power stroke twice in one full revolution of the crankshaft. With the crankshaft set for 90 degrees, you not only get self starting capability, you also get a power stroke every 90 degrees, so consequently the engine should run much smoother and slower with a 90 degree crank.---Brian
    Brian Rupnow

  10. #10

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    I was only going to suggest that nicely but I regret I'm too late.

    The 180 crank has better balance but that's not enough of an advantage to offset the other problems. I don't know if judicious balancing holes in the flywheel would be worth considering. They would be ugly unless you hid them under an outer rim ring.
    .
    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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