I made the coupler smaller in diameter to reduce the  polar moment
of inertia and gyro reaction stress. The  4130 rectangular
tubes are off the shelf at AC Spruce.  The advantage of
this design is: everything can be  changed if necessary.
For example if the main 4130  plate cracks the thickness
can be increased in later  version.

It does not depend on a proprietary part  that could
be discontinued at any time. I will build  one some time
this year.

Paul Lamar

Getting the driving and driven elements into the same plain is the  key,
so as to eliminate bending loading in the discs. Would not round  tubing be
just as effective and easier to machine and install?

Lynn E. Hanover

It cries out for more or less rectangular blocks of rubber :)


Paul Lamar