The Craftmans Shop > Model Engineering
Rockerblock engine--something a little different--
Brian Rupnow:
So--Today we made a start. I like cutting gears. I especially like making gears from left over bits and pieces that I have laying about. I always drill a pair of holes the calculated distance apart in a piece of scrap and fit the gears to shafts which set in the reamed holes. It is much better to do it this way and correct any "tightness" in the mesh, rather than trying to do it in a partially assembled engine. These gears seem to be "just right", although that is never a certain thing.
Brian Rupnow:
The crankshaft is a much more convenient place for the points. True, you get a spark with every engine revolution, but so what? There is nothing in the cylinder to burn on the exhaust stroke, so it doesn't matter. This is known as a "waste spark" ignition. Almost all of my single cylinder engines are built that way.--Brian
Brian Rupnow:
I think that to make the con rod a two piece like I'm thinking of, two separate pieces would have to be machined and bolted (and possibly dowelled) together as shown in the first picture. Then after they are firmly bolted and possibly dowelled together, the hole gets put in as shown in the second picture. The sides would have to be match marked to make sure they went back together the same way they came apart. Then they could be separated and put back together around the rod journal.
Brian Rupnow:
Here is a cross section thru the centerline of the engine. You can see how tight it gets between the rod cap and the underside of the water jacket. Of course, since it is a pressed together crankshaft, I could use a conventional closed rod end and assemble the rod when the crankshaft is pressed together. there's just something about doing that that makes me quiver all over----
Brian Rupnow:
Nope, flywheels won't drag. Won't clear by very much, but won't drag either.
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