Re: Kilian's mount: Parts are getting purchased.
Bob Luffel (bobl@hpgrla.gr.hp.com)
Fri, 28 Apr 95 15:45:06 MDT
>
> Bratislav, I liked your post on tube stiffness and the 4^ power. Now that
> surely affects deflections purpendicular to the axis, but what about
> torsional deflection and vibration when using stepper motors? I guess
> there are 3 degrees of deflection, axial, longitudinal and torsional.
> Just speaking about the shaft or tube, not the mount. Longitudinal is a
> throw-a-way. Ah, the art of amateur telescope making can get into the art
> of structural analysis, can it not?
>
The polar moment of inertia of a shaft (or tube) is also to the 4th power,
so torsional stiffness is increased to the same degree as
transverse bending.
I have always wanted to drill out the center of my German Equatorial's
stainless dec. shaft to lighten it, but drilling long straight holes can be
a challenge (though gun-makers solved this one long ago...).
Bob