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.
Thanks Paul, that is a book that I would like to read. It is
amazing and inspirational what truly talented people can accomplish
even with primitive equipment. I might try a single rotor e-shaft
as a turning project, working out the process in mild steel
first. Jerry
In an E-shaft case you would do the rotor bearing first
with the chunk on centers. Then cut the mains with off set
centers.
Rather than cut it with a cutter you might try a cheap
bench grinder mounted on the cross slide. The problem with
cutting it is the tool has to dig in each time the chunk
of steel comes around. It will never be in a continuous cut
until the main is almost the right size. That causes a severe
vibration. Maybe a grinder would be a lot smoother as it is
only taking off a thou or so on each rotation.
This is why engine makers start with either a casting or
forging that is roughly the right size to begin with.
Conceivably on an NC lathe the cross slide could move in
and out during each revolution to keep the cutter in proper
depth contact most of the time. I don't know if this is done
or not. It is a lot of monkey motion. I have never even seen
a crank grinder. Here are a few pictures from the WWW.
Looks like the chucks are on rotating cross slides and the grinding
wheel is very large diameter. http://www.alsblowers.com/grinder.html
If it were me I would not bother doing it from scratch.
Let them come up with a two rotor e-shaft and cut it down.
Richard Sohn made one that way. Perhaps he will describe
how he did it.
Paul Lamar ...No rotor no motor.
I found the book at the Wright State Library. It is for sale at
$34.00. Jerry
http://www.libraries.wright.edu/special/publications/
Go for it Jerry. Great book.
Paul Lamar ...No rotor no motor.
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