Trying out a new Altitude drive

My 18” UC Dobsonian uses a toothed belt to drive both axes. The azimuth is neat and hidden below the base. The altitude drive is effective and efficient, but does look ‘unusual’! One of its great features is the adjustable slipe clutch - which is a priority for me.

I like the idea of the roller drives used by SpicaEyes and a few amateur builders. It drives both trunions together and could make the scope even more compact and easier to assemble. But could it incorporate a clutch and how well balanced does the scope need to be? Of course the answer is to build a prototype and experiment.

IMG 4790

Here is the prototype. No base yet, just the telescope mirror and trunnion assembly sitting on the rollers, mounted on one of my workshop benches. Seems to work OK, but I need some decent rubber rollers. Heatshrink over plain bushes just doesnt work well!

IMG 4791

Not installed yet is the actuator for the clutch. I’ll try it first as a straight friction-slip clutch but as a fall back I have a mechanism tested out to motorise it.

© AstroKeith 2022