George,    producing e-shafts is beyond my ability.  It is not a
simple thing.  BTW, I took the problem to the local technical college
to a guy who builds small steam engines that are works of art.  His
opinion is that a one-inch crank throw is about  maximum for a manual
lathe  which is far less than an e shaft would require. I cannot
imagine a way to do it on a lathe but I would be pleased to learn if
anybody knows how.   People have been building cranks for years but I
could not find a description of the process anywhere including
google. There are cast cranks and forged cranks. Are there also
billet cranks turned out by CNC lathes?        Jerry

Yes on the billet cranks. You take a huge chunk of steel
and use a large four jaw chuck with the chunk of steel off set
the same as the stroke.  The other end has a center off set as well.
You support that end with a live center. Start hogging the rod journal
or rotor eccentric at very low speed due to the off set mass. Leave a
large flange on the live center end. When the rod journal is done.
Reposition the chuck around the center of the main bearings and cut
the mains. When finished cut off the temporary flange on the live
center end. Needless to say it takes a very robust lathe.

The Wright Brothers mechanic Charles Taylor started with
a thick flat slab of steel 6" by 31" by 1-5/8". Drilled a lot of
holes in the slab using a drill press. Then knocked out the unneeded
pieces with hammer and chisel. Wound up with the shape of a single
plane, four cylinder crank. Then used something similar to the process
I mentioned above. He built this on a 14 inch lathe. The crank
stroke was four inches as was the bore. He machined and assembled the
motor in six weeks once he had the aluminum block casting.

This was extensively described in a book called "Charles E. Taylor
1868 - 1936 The Wright Brothers Mechanician"
by H.R. DuFour Limited 1997 First Edition signed by the author
belonging to my wife Robin. ISBN 0-966 9965 -O-X

BTW the Wright Brothers totally understood the relationships
between HP, Torque, Thrust, RPM and speed.

Paul Lamar ...No rotor no motor.

Paul,
That pretty much how I see it as well and I discussed this with a local
machinist. Jerry the eccentric is only 15mm, but I guess your saying it's a
30mm throw. It is important to get the eccentric as accurate as possible,
although the apex seals do allow for some error. One of my reasons for
wanting CNC is to maintain the accuracy for eccentricity.

The local chap said he would rough it out on my machine for free, just as a
neighborly gesture, I have helped him a lot, but I'd prefer to look for
accuracy and repeatability of CNC.

Paul was correct to say you need a four jaw chuck for the drive end on a
manual lathe, but you really need to clock the live centre end  for
reasonable accuracy to maintain that 15mm.
George ( down under)


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