I am adding a drive system and Dan’s SiTech Servo Controller to my 22” F5 Dobsonian. I plan to use it in "drag and track" mode for visual observing. After about 8 years, I have gotten just a little bit tired of nudging the scope to keep things within the field of view.

It looks like I will be able to hide all the mechanicals within the rocker box. Almost all the parts are made and I plan on doing a partial mockup before I actually start cutting into my scope.

I will post  pics as things progress.

Gary Rizzuti

Azimuth Drive - mockup


The drive for the azimuth will go in a corner of the rocker box. Here it is mounted on some scrap plywood, which is standing in for the base of the rocker box. The 2 vertical pieces just show the location of the corner of the rocker box. Under this is a 29” dia. plywood wheel with a timing belt wrapped around it.


The drive mechanism is a motor connected to a 20:1 right angle drive. A couple of pillow block bearings above and below the rt angle drive position a drive shaft that goes through a hole in the base to drive the timing belt.


There is the “standard” Ebony Star and Teflon bearing between the rocker box and plywood wheel and between the wheel and the ground board. The white strip around the edge of the wheel is Teflon. You cannot see it but there is also a disk of Teflon around the center pivot (bottom center of picture).


I was not sure if I could get away with just bolting the drive to the base of the rocker box and still keep a consistent tension on the belt.  What I did was to spring load the drive mechanism so that it can move in and out a bit. The 2 small ugly blocks in front of the drive have a spring between them.  I did a bit of limited testing and it looks like it should be possible to just bolt everything to the base.


In picture below you can see the drive pully and the plywood wheel. The Ebony Star on the bottom of the wheel extends out a bit beyond the wood. I thought this might help to keep the belt from ever slipping off. I'm not sure how good an idea this actually is, I guess time will tell. Does anyone have any thoughts on this?  Along the bottom edge of the picture you can see just a bit of the ground board.