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Thread: Design and build Side-shaft hit and miss from barstock

  1. #1
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    Default Design and build Side-shaft hit and miss from barstock

    I have spent enough hours this summer frittering away my shop hours on flame-sucker engines, Sterling engines, and clutches. My plan for the coming winter is to design and build a side-shaft hit and miss engine from bar-stock. I have built enough engines now that the only really "new" thing will be the gears that run the side-shaft, and the governor that controls the "hit and miss" action. I hope to purchase gears, bearings, etcetera from commercial dealers so that when I eventually have a running engine, other people will be able to buy the same parts from the same dealers. The engine will be water cooled, with a horizontal cylinder, 1" bore and 1 3/8" stroke. The intake will be an atmospheric valve with no cam to actuate it. Probably about 90% of this engine will be similar to parts I have machined before on the Kerzel and the "Odds and Ends" engine from Philip Duclos. I don't plan on using a Viton o-ring for a piston ring, because although they create a wonderful seal on the piston, I think they have enough residual "drag" that they prevent the engine from having very many "miss" cycles. In fact, I hope to use no rings at all, but will lap the piston into the cylinder for an air tight fit like I did on my marine engine. I hope to aim for a compression ratio of about 4.5:1. Ignition will be the Dodge points and condenser that I have used on all of my other i.c. engines. Both piston and cylinder will be grey cast iron, and the flywheels (2-of) will be 6" diameter. I am still doing research on the cam and governors, and haven't fully decided what I will use. Whatever it is will no doubt be a copy of someone else's successful design.---Brian Rupnow
    Brian Rupnow

  2. #2
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    Brian, you have my undivided attention now. I like the idea of what you're suggesting. It might be one of the few times I buy plans for something I didn't design myself.

  3. #3
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    George Britnel showed me pictures of how the governor works on a "domestic stovepipe" hit and miss engine, which he has recreated on a very small "tiny" hit and miss engine--It took me a while to get my head around this, but I think I have it. Things are not modelled to any particular scale, but that's okay for "show and tell". Red indicates the flywheel. The light blue indicates the round part which fits over the flywheel with about half a thou radial clearance. The slot milled in the center of that light blue part is long enough to give the offset required. The light blue part has a rod extending from one side of it thru the pink counterweight and thru the spring and thru the light brown bracket. The pink counterweight is firmly attached to the rod. The rod goes thru the light brown bracket with a clearance fit.--Normally, at zero rpm, the spring holds the light blue part centered on the crankshaft. As the rpm increases centrifugal force makes the pink weight want to move away from center, and as it does it pulls the blue part away from center until it is limited by the other end of the slot coming up against the crankshaft. The dark blue eccentric strap and rod which runs out to the bell crank doesn't move at zero rpm. as nothing is eccentric. As rpm's climb and the light blue part becomes more and more eccentric to the crankshaft, the eccentric strap follows it and the rod extending from the eccentric strap moves in a linear motion to operate the bell crank at the far end to lock out the exhaust valve.----Brian
    Brian Rupnow

  4. #4
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    Something about the previous explanation troubles me. Obviously, the counterweight and the light blue part it is attached to have to rotate with the flywheel in order for centrifugal force to pull the light blue part off center. At zero rpm when the light blue part is centered on the crankshaft, the dark blue eccentric strap and attached rod isn't going to move.---But--As soon as the light blue part is pulled off center the eccentric strap is going to follow it, and the rod attached to that eccentric strap is going to move back and forth. Somehow I think that the rod attached to the eccentric strap shouldn't be bopping back and forth to do it's job properly. What am I doing wrong?
    Brian Rupnow

  5. #5
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    It moves farther (twice as far) when it is "engaged" (eccentric).

    That should be the rod for the exhaust valve, so it would be open when not eccentric (miss), and opened and closed so the engine takes in a charge and has compression when in "hit" mode.

    I'd expect some sort of over center type setup so it is either in valve closed or valve open mode, because I see issues with it being in a "part open" position.

    Thanks for the explanation, I had misinterpreted the mechanism as some sort of dog clutch.
    1601

    Keep eye on ball.
    Hashim Khan

  6. #6
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    Okay--George came thru with an explanation---"You're correct about the strap and lock-out rod moving back and forth. The trick of this is when the rod moves forward it pushes the lock-out lever into contact with the rocker arm but the lock out lever isn't fixed to the lock out rod rather the lock-out rod slides through the lock-out lever so it only pushed it in one direction. There is a stop on the lock-out shaft that moves the lock-out lever. If you look at picture 9422 you will see that the end of the lock-out rod is threaded and has 2 nuts on it. The one nut is for adjusting how far the lock-out lever moves and the other is the lock nut. The travel of the eccentric has to be greater than the required movement for the lock-out lever so that's where the adjusting nuts come into play."
    gbritnell.
    Brian Rupnow

  7. #7
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    I have checked out the two part numbers for the helical gears from "Martin" in USA that are on the engine being built by Craig DeShong. The 12 tooth helical gear is part #BS1612-2 and sells for $38 USA. The 24 tooth helical gear is part #BS1624-2 and sells for $63 USA. That comes out at $101 American money and $133 Canadian money. Ouch!!! Maybe it's a good thing that I'm rich instead of good looking.
    Brian Rupnow

  8. #8
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    In back issues of the magazines, there is an article on making helical gears. I forget the author's name, but it was a good article. You could make your own.....
    1601

    Keep eye on ball.
    Hashim Khan

  9. #9
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    Jerry--Chuck Fellows posted a pdf about his method of making helical gears, and George Britnell also posted his method. It looks like they got good results, but it looks a bit daunting to me. Thing is, if I sell the plans to this engine I think most people would rather spend the money for a finished pair of gears than trying to make them.
    Brian Rupnow

  10. #10
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    Quote Originally Posted by brian Rupnow View Post
    Jerry--Chuck Fellows posted a pdf about his method of making helical gears, and George Britnell also posted his method. It looks like they got good results, but it looks a bit daunting to me. Thing is, if I sell the plans to this engine I think most people would rather spend the money for a finished pair of gears than trying to make them.
    You could make them of a size that either would fit. Just a suggestion. Possibly in mind because I have a plan to set up to make them myself....

    It is true that it is hard to "fake it" with helical gears. You do it or you do not, there are not "degrees of proper-ness" as with bevel gears, etc.
    1601

    Keep eye on ball.
    Hashim Khan

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