Re: ATM equatorial platform

["pdk" <pdk@tampabay.rr.com>]

.
>
> >  2. I just read in a recent ATM message: "... and dont use soft rubber
> roller
> >  blade wheels or your scope will float like a boat"

The preceeding message was included as a warning for folks who see pictures
of an early prototype of an equatorial platform a friend and I made.
We doubted our ability to make a "perfect" sector, so we thought the
urethane would average the flaws down due to the spread of the contact area.
That it did, and more.  It was fine the first few nights I used it. Then the
breeze
came.  :-(

bottom line...   plain old bearings.

as far as radius of the cone on which your sectors are based I can report
this.
if you use the following assumptions...
A CG of approx 24 inches.
A 1/4 20 threaded rod.
A very stable dob.
A judiciously chosen stepper motor.*
A basic stepper controller that half steps.

You will be hard pressed to see flaws in the design.
Construction flaws MAY be a different story, mine you cant
not that it does not have them, I nor the experienced viewers I have had
observing with
it, saw them to be an issue.
I still personally would opt for a "slightly" longer rather than shorter
radius due to the
enhanced gear / step size.

PK