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Thread: Vertical hit and miss engine

  1. #141
    Join Date
    Mar 2008
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    Barrie, Ontario, Canada
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    So here we are, all ready to rock and roll. The cad model shows the crankshaft overlayed on the material which it will be cut from. The crankshaft will actually be 1/2" longer at both ends to match up with the raw material. Then it will be trimmed to length after all turning is completed to get rid of the countersunk ends. The picture shows the 1144 stress proof all ready to go into the lathe. I am going to spend some time tomorrow making a new lathe dog that doesn't rattle back and forth between the chuck jaws. That scares the Hell out of me.

    Last edited by brian Rupnow; 08-07-2019 at 08:16 PM.
    Brian Rupnow

  2. #142
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    Mar 2008
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    Barrie, Ontario, Canada
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    First section of crankshaft is turned between centers. I kept checking it with my con rod until I was happy with the fit. Last evening I had all kinds of ideas for a new, super duper lathe dog that would fit on both sides of a chuck jaw. This morning I looked at what I had, and decided to just drill and tap another 1/4"-20 hole in the opposite side of the machinists clamp. Now I have a bolt setting on each side of a chuck jaw, so it doesn't rattle back and forth between chuck jaws. Works great!!!

    Brian Rupnow

  3. #143
    Join Date
    Mar 2008
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    Barrie, Ontario, Canada
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    So there we have it gentlemen--a crankshaft at 95% finished. I still have to trim the ends and do a little clean-up, but that is a full days work. I really liked the way my new improved lathe dog worked. Now my back hurts from standing at the lathe all day, and I still have to go for my "fat mans walk". That blob in the center is a spacer glued in place with hot melt glue to keep the center gap from closing up when I tighten the tailstock center.
    Brian Rupnow

  4. #144
    Join Date
    Aug 2016
    Location
    Appalachian Ohio
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    802

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    Quote Originally Posted by brian Rupnow View Post
    That blob in the center is a spacer glued in place with hot melt glue to keep the center gap from closing up when I tighten the tailstock center.
    I have learned a lot from you. Thank you.

  5. #145
    Join Date
    Mar 2008
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    Barrie, Ontario, Canada
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    Thanks Dan--It's always a good day if people learn something from me. The crankshaft is finished except for the keyway, which I will probably cut tomorrow. The main thing that I don't like about turning between centers, is that you can't readily check the size you've turned to by sliding the bearing over the shaft. You just keep checking with your micrometer and praying you don't turn undersize. In a perfect world, I like to leave about 1/2 a thou on the shaft and take that down with 200 grit carborundum paper. In this case, I must have guessed right, because a 3/8" bearing will just start to slide onto the shaft ends. A bit of sanding should bring things right. 1144 stress-proof steel does move a little when machined. Not anywhere near as much as cold rolled or even A36 steel, but it still moves some. The crank as shown has about .010" total indicated run-out. If that poses any problem when I assemble the engine, I will set one end up in the 3 jaw chuck and whack it with a dead blow hammer. These little one piece crankshafts are amazingly flexible.
    Brian Rupnow

  6. #146
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    Mar 2008
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    Today was major assembly and gasket day. Everything was calculated to have the outside to outside measurement of the crankshaft hubs to match the inside dimensions of the side-plates and bearings, with the cylinder being exactly in the center. It was close---really close, but no cigar. However, I knew that by the time I put a 0.030" gasket between the side-plates and center section, that it would free up a bit of room. It did, everything cleared and went round and round. I was afraid that I was going to break the cast iron rings when trying to put them on the piston. 10w30 oil saved the day, and I got them on VERY carefully. Then came the question of how in heck do I compress the rings so I can get the piston into the cylinder. This lead to dismounting the cylinder, putting it up in the lathe, and turning a 30 degree internal chamfer on the end which sets closest to the engine. That worked, as with a good deal of butt-clenching I tapped the piston with rings mounted on it into the cylinder (again with lots of 10w30 oil. So--Engine is assembled and everything clears when I turn it over by hand. All I have left to do on the engine is to make the counterweights which mount on the crankshaft.
    Brian Rupnow

  7. #147
    Join Date
    Mar 2013
    Location
    West coast of Canada
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    Here is a trick you can put away in your bag when you don't have a ring compressor for a small bore engine. Get a hose clamp that fits the size you need. Take a pair of side cutters and carefully make some raised notches like you would see on a ring compressor. Put the clamp on with plenty of lube and tighten it up, then back off slightly. Put the piston in the bore and tap lightly keeping everything straight. It should slide right in without too much diffeculty.
    Larry

  8. #148
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    Mar 2008
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    Barrie, Ontario, Canada
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    Larry--That was what I tried first. Didn't work. It does compress the ring everywhere but underneath the screw (it was a gear clamp). I frigged around with clamps for half an hour before putting the cylinder back up on the lathe and turning a 30 degree lead in on the bottom.
    Brian Rupnow

  9. #149
    Join Date
    Sep 2012
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    Wellington county Ontario Canada
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    I have used the skin from a beer can with a zip-tie for a ring compressor on an old inline 6 Merc outboard, worked great with lots of lube.
    Awesome work as always Brian!
    Cheers,
    Jon

  10. #150
    Join Date
    Jun 2007
    Location
    Anderson SC
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    1,492

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    Quote Originally Posted by brian Rupnow View Post
    Larry--That was what I tried first. Didn't work. It does compress the ring everywhere but underneath the screw (it was a gear clamp). I frigged around with clamps for half an hour before putting the cylinder back up on the lathe and turning a 30 degree lead in on the bottom.
    Next time you are out, stop by a auto supply and get a high pressure hose clamp. That type clamp is a smooth steel band full circle on the inside and smooth. They are a newer hose clamp style intended for the higher pressures of todays fuel injected cars.

    Commercial cylinders on lots of engines have a taper like you made on the lower edge of the cylinder. Its very common.

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