On Wed, 14 Apr 2004 10:06:21 -0700, "Evan Gatehouse"
wrote:


"jimthom" wrote in message
. com...
Thanks again for your ideas.

The problem is really what type of coupling to use to resist the
torque forces of the tiller. If I could use flanges, the total
x-section area of the bolts that hold the flanges together should be
the equivalent to the x-section area of the rudder post, so there is
the potential for a lot of torque. As you said, splines may losen and

Uh I don't think so. The polar moment of inertia should be the same
shouldn't it rather than cross sectional area?

So a few little bolts on a very large diameter flange would have the same J
as a rudder stock that is very close to centerline.

Evan Gatehouse

Evan's point should not be hard to grasp in the context of a
tiller/rudder post. A determined push from Jimthom's hand on a three
foot tiller could wring off a one inch rudder post entirely.
Think of it as a 3 foot wrench on a big bolt. Ah, the power of the
lever.
But in this thread, the traditional fixing for the bicycle crank keeps
coming to mind. The old-fashioned pedal crank fixing seems to have no
trouble handling a repetitious, cyclic load of up to 240 pounds at an
arm of 10 inches, 60 rpm for 20 years plus on a 3/4 inch shaft.
All done with smooth round holes, and a single flat worked on the
shaft.....
The cotter bolt is what works the magic: its tapered flat of less than
1/12 slope will hold the shaft tight, even without its fixing nut and
lock washer....

Brian Whatcott Altus OK