Re: ATM equatorial platform

["Richard Schwartz" <richas@earthlink.net>]

If you want to "average" the sector flaws down, you might try something
similar to what we do in a flotation system: replace each roller with two
rollers on the ends of a lever.   Don Clement will argue with me on this
next point, but that lever should be pivoted on a blob of silicone.   (Don
will tell you to use a piece of steel measuring tape, of course.)

. . . Richard

----- Original Message -----
From: "pdk" <pdk@tampabay.rr.com>
To: "atm" <atm@shore.net>
Sent: Thursday, January 16, 2003 3:57 PM
Subject: Re: ATM equatorial platform


>
> .
> >
> > >  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
>
>