Well I got around to take some photos of the upgraded astrophotography tracker and to describe my progress.
A few months ago I abandoned work on the tracker due to mechanical instability and started playing with a mini-mill to make a large worm gear and worm. The process has been reasonably successful but I think that I can only use about 1/4 of the worm gear due to concentricity problems. As I used a small mill as a lathe to try to get the worm down to a perfect disk, some flexure in the setup caused the machined aluminium disks to be less than perfect. The cutting of the 130mm worm gear went very well and only took about 1 1/2 hours to cut and polish. See some of the previous posts for the detail.
I had to assemble the worm and stepper motor assembly to the mount and it looks a bit “wonky”, but it works. I have not done any testing yet except to see how smooth the gear operates. It becomes quite sticky and I marked out a quarter of the worm gear disk as useable. That’s ok as it represents 6 hours of continous tracking and it is very fast to backtrack with the controller to the beginning of the “good” section of the worm gear.
The mount makes provision for my imaging camera (normally a Canon 600D or modified 350D) with a set of Canon and Tokina lenses. Tracking is done with a webcam mounted on a Canon lens. The rest of the setup is described in previous posts.
I will now try some bench testing to see how accurate this mount will be. I will also have to re-calibrate the stepper driver to get the correct stepping rate for the specific gear ratio (1:269).