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  1. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    I've just had one of those days where I worked all day and have very little to show for it. I had to make a fixture to align the exhaust flanges with the exhaust pipes for silver soldering. It was one of those fixtures that has to be destroyed to get the parts free from it after soldering. The...
  2. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    YAY!!!---we got fire!!! Last week I went to a snowmobile wreckers and brought home 3 twin lead coils. I couldn't get any of them to work, and thankfully the owner had said that if I couldn't get them to work he would refund my money. Today, as a last resort, I cannibalized the twin lead coil off...
  3. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    This morning I'm wrapping things up. Everything is machined except for the pushrods. I tried to buy shorter set screws for the cams, but everybody is closed today for "Family Day". I tried to buy some metric o-rings to finish off the gas tank, but again, everybody is closed. About the only...
  4. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    The cams are machined, heat treated, and installed. One cam was uglier than usual, so I didn't heat treat it until I had worked my magic on it with a flat file to bring it's contour into a match with the other three cams. I didn't have quite enough room between the camshaft and the underside of...
  5. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Of all the things I do, and I do a lot--I especially hate making cams. I know the formula for calculating cams. I know half a dozen ways to make the cams. The way I make them on my milling machine works for me, but they take forever to make and are a great pain in my a$$. I started this morning...
  6. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Today is cam day. Yesterday I purchased a 12" length of 01 steel (these cams will be hardened). The first step was to turn the o.d. to 0.448" which coincidently is the largest diameter of the cam nose. Next step was to drill and ream the center hole to 0.188". I have parted off two 2" lengths of...
  7. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    I'm down to the ignition and the cams. The ignition is making me crazy right now, so I've decided on a final design on my cams. I have decided to make four identical cams, each one with a hub attached which has two set screws, That way I can set my time camming to whatever I think it should be...
  8. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Jason--At one end of the crankshaft, there is a collar that rides up against the inner race of the ball bearing. The other end floats right now. The con rods seem to locate the crankshaft so I'm not sure if I need to put a spacer on the crankshaft at the other end.----Brian
  9. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Maybe try scoring the glass on both sides first?
  10. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    I just had to assemble the crankshaft with the con rods and pistons to see if everything went round and round and up and down without hitting any obstructions. I'm very pleased with the results.---Brian
  11. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    This morning I finished cleaning up the crankshaft, cut the counterbored ends off, and made/installed the counterweights. After yesterdays marathon crankshaft making day, I'm going to take it easy today.
  12. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    So there we have it.--Fully machined one piece crankshaft. I thought that I could make one in a day, but it's been a long day. Started about 9:00 this morning, and it's almost 9:00 in the evening now. I still have to trim off the ends with the counterbores and drill and tap for the...
  13. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    The crankshaft "throws" have been machined to size. To test them for accuracy I bolted the connecting rods into place. The rods will turn with a small bit of force, but they don't flop straight down under the influence of gravity. I'm happy with the machining. Now I tear down my set-up, do some...
  14. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Now we get to the scary part---What can be cut away with the milling machine and what has to stay because it's part of the crankshaft. This always makes me check about four times to make sure I'm not milling away part of the crankshaft.
  15. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    The crankshaft has one more flat edge, so a third set-up in the vertical mill is required to make certain that the third flat side is perfectly perpendicular to the other two sides.
  16. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Here is a rather nasty picture of me holding a steel ruler beside the machined crankshaft. as far as I can tell, any bowing during machining was very minimal.
  17. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Now the round stock has been flattened on both sides. When I flattened the first side, I just laid the piece in one of the grooves in my mill table. To do this second cut, I slid a set of parallels under each end for the previously cut flat to lay against. This ensures that my two opposite...
  18. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    So, here we are with the first side of the crankshaft milled flat x 0.300" deep. Did it bow when I took so much from one side? Maybe, but not very much or I would have noticed the endmill taking a heavier or a lighter cut.--Tomorrow I will flip the crankshaft over 180 degrees, put a piece of...
  19. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Okay kiddies--Let the fun begin. This is a piece of 1 1/8" diameter 1144 stress proof steel. My first job will be to cut it to 9.403"" length, then remove a slab from each side until I am left with a "plank" 1/2" wide. This will involve milling 0.306" from each side of the round. This length...
  20. Brian Rupnow

    Building a twin cylinder inline i.c. engine.

    Okay--Now we are going to get down to the part that everybody has been asking about---the crankshaft. I just got a price of $9 for a 9" length of 1 1/8" diameter 1144 stress proof steel from my local supplier and will pick it up later today. I've had lots of questions about the one piece...
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