Re: [ATM] Concept Review - Dob Mounted Roller Drive / Feedback

[Gilbert Gagne <gil5941@earthlink.net>]

My equatorial platform is driven this way except that the stepper motor 
drive roller assembly is spring
loaded on a  pivot. It can swing out of the way and be locked when not 
in use to prevent permanent
deformation of the sector surface material. This involves some extra 
complication but also allows you
to adjust the roller pressure via different springs.
Gil Gagne
Port Orange, FL

Peter wrote:

>Hi,
>
>I'm working out the design of my next big Dob and I wanted to get some
>feedback about an idea to have the Alt drive and encoder feedback friction
>fed. The obvious reason for doing this is to make a simple plop and go scope
>which does not require encoder or drive installation.
>
>The idea is to replace the glass laminate on the Alt bearing with hard
>rubber running on 4 knurled rollers. One roller will drive the Alt encoder
>through friction and a second roller would be connected to the drive motor.
>Please see the simple sketch: www.kitgear.com/atm/roller.jpg
>
>One concern I have is if the scope sat for a few weeks or months would the
>rubber deform on the 4 roller lines of contact and cause a problem? I'd also
>like to know if you think the friction would be sufficient to adequately
>drive the encoder? I live near the Great Lakes so summer time humidity / dew
>is high, hence the high friction rubber.
>
>If the consensus if that the idea would work then I'd like to do the same
>with the Azimuth drive and encoder so I can use a low profile flex rocker.
>The encoder count would have to be reduced by the drive ratio.
>
>All other ideas are also welcome.
>
>Thanks,
>
>
>Peter
>
>_______________________________________________
>ATM mailing list http://www.atmlist.net/
>
>  
>
_______________________________________________
ATM mailing list http://www.atmlist.net/