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To make a 2 - 3/4'' X 3/8'' flywheel I started with a 3'' X 1/2'' brass disc. It was a little larger then necessary but when buying scrap your options are limited.
The 3/8'' deep recess and the crank shaft bore were done in the lathe using a three jaw chuck. The flywheel blank was then mounted in a spin index using a machined 1/2'' mandrel. The six holes through the rim and part way into the center hub were drilled and reamed. For this particular pattern every other hole was offset 40 degrees. This is a simple index of 0-4-12-16-24-28. The picture shows the spokes cut oversize in length and already soldered in place.
After cooling the blank was returned to the chuck for a final facing to remove the 1/8'' thickness left from the first operations that held the rim and hub as one piece. The flywheel was then mounted on a mandrel that was machined and left in the chuck. This assured that all faces could be machined to run true. This picture shows those completed operations plus a light sanding over the solder joints in preparation for painting.
And here's the final picture showing the finished flywheel. This spoke arrangement is an interesting variation of the traditional six spoke flywheel.
The 3/8'' deep recess and the crank shaft bore were done in the lathe using a three jaw chuck. The flywheel blank was then mounted in a spin index using a machined 1/2'' mandrel. The six holes through the rim and part way into the center hub were drilled and reamed. For this particular pattern every other hole was offset 40 degrees. This is a simple index of 0-4-12-16-24-28. The picture shows the spokes cut oversize in length and already soldered in place.
After cooling the blank was returned to the chuck for a final facing to remove the 1/8'' thickness left from the first operations that held the rim and hub as one piece. The flywheel was then mounted on a mandrel that was machined and left in the chuck. This assured that all faces could be machined to run true. This picture shows those completed operations plus a light sanding over the solder joints in preparation for painting.
And here's the final picture showing the finished flywheel. This spoke arrangement is an interesting variation of the traditional six spoke flywheel.