ATM [Fwd: BOUNCE atm@shore.net: Non-member submission from [Dan Gray <grayarea@teleport.com>]]

[Mel Bartels <mbartels@efn.org>]

 owner-atm@shore.net wrote:

> From: Dan Gray <grayarea@teleport.com>
> X-Mailer: Mozilla 3.0Gold (Win16; I)
> To: atm@shore.net
> Subject: ATM Drive Roller Slippage
>
> Hi all.
>
> I'm not on the list right now (to many messages per day), but I'm
> still
> activally ATMing.  Please respond directly to me, and to the list if
> desired.
>
> I have a problem with the roller drive on my altitude axis.  Please
> take
> a look at my scope if you have a web browser at:
>
> http://www.tms-usa.com/14inch2.htm.
>
> This doesn't show the drive system because I haven't updated the web
> page lately, but it does show the drive rollers..
>
> I am driving the altitude axis at FOUR points, and am still getting
> some
> slippage!  I have it down to about 1.3 minutes of arc, and that's
> going
> from horizon to zenith, and back to horizon again. That may not seem
> like much for a portable scope, but I want to be able to point to
> within
> 2 or 3 minutes of arc, and this slippage is going to accumulate every
> time I slew the scope.  I added aluminum flat bar on the large drive
> circles (41" in diameter) so now it's 3/4 inch diameter ground and
> polished steel shaft against 1/8th inch by 1 inch flatbar aluminum.
> This is an improvement over steel against the epoxy casting resin, but
>
> still too much slippage.
>
> The slippage is directly related to the balance of the scope.  It
> slips
> more, and in the direction of the balance, when extra weights are
> added.  I want to be able to add a ccd camera or other accessories
> without worrying about counter weights, so if anyone has any ideas for
>
> better friction, let me know.
>
> I did have slippage on the azimuth until I put aluminum sleeves on the
>
> azimuth rollers.  Now I'm getting practically no slippage on azimuth.
>
> Thanks all.
>
> Dan Gray.



--
Clear skies, Mel Bartels    Programmer/Analyst, amateur astronomer
Eugene, Oregon, USA         homepage: http://www.efn.org/~mbartels
mailto:mbartels@efn.org     atm, atm-digest list-owner
Motorize A Dob: http://zebu.uoregon.edu/~mbartels/altaz/altaz.html