Re: Geared Dobsonian question

Mark Suchting (masuch@dap.CSIRO.AU)
Wed, 8 Mar 1995 10:58:28 +1200 (EST)

On Mon, 6 Mar 1995, Mel Bartels wrote:

> I have used roller bearings to reduce friction on my dobs
> for years. For manual dobs, I let 2/3 of the contact pts
> be roller bearings and the other contact pts the standard
> formica/teflon. This cuts the friction down on very large
> dobs to a more managable level.

Mel,

How do you make the bearing surface in this configuration? An aluminium disc with a formica anulas(?) at the very edge for the teflon pad to run on ?

> For my computerized dobs, the 3rd point is a machined conical
> shaft attached to a precision gear reducer. With the roller
> reduction of ~40:1 and the gear reducer of ~60:1 giving a
> total reduction of 2400:1, one can attach motors directly
> to the gear reducer input shaft without need for further
> gearing.

I downloaded your altaz.zip package. Very impressive. I wondered...do you do all your coarse telescope pointing via handpadle slewing? I assumed this as there doesn't seem to be any clutch system on the motors.

Your drive system has rejuvinated my plans for a 20" binocular ( I have the glass ), but I imagine that I will need a driven roller on both altitude bearings. Would this be a very complex modification to your setup? Could I perhaps just use a more powerful motor on one side?

Cheers, Mark.