Building the crankshaft .......
I started by making the steel blanks for the throws to size and square on the mill and surface grinder. The center throw was made in a rectangle .875" thick x 2.750" high
and 1.594" wide. End throws are .625" thick .875" wide x 1.875" long.
With a mill stop in place and the hole location established on the center throw I spot drilled, rough drilled and used a under size end mill to flat bottom the bores. I decided to use blind holes in the throw rather than through bores as shown in the original plans. Flipping the part against the stop for each hole.
Using ground .500" diameter 12L14 round stock for the journals the bores were sized to allow a bare slip fit with no " wobble " to the mating part.
Similar operations were made to the end throws. These bores are through the part.
The center throw profile was next. A layout was made and the excess stock was band sawed from the blank. Set up on a sine bar to mill the remaining stock within a few thousands of the the layout line. At the surface grinder the final size and finish was completed.
Another setup was made at the grinder to add the 45 degree chamfers where needed on the throws.
Some finish bench work and the journals cut to length the parts were ready for assembly. A " U " shaped spacer was made to establish the distance between the throws where the connecting rods fit. A slight groove was file in the bores to allow air to escape when using Loctite. All parts were primed with Loctite primer and the crank was assembled in stages. The final assembly was done on a small granite plate to insure everything was in alignment.
The end results were excellent with the crank running true.
All done, well not quite ! Later on in the build the joints slipped and threw the crank all out of alignment.
After two separate attempts and some time later I finally was able to save the crank without starting all over. Might have been easier !
The " new " crank shown later in the build has .562" output ends made from W1 drill rod due to resizing the end bores during the fix and I thought would be a little stronger, too.