I recently acquired a Chinese CNC router (6040). I'm really interested in trying my hand at a goto EQ mount for astrophotography. I have an Avalon M Uno that is totally beyond what I need but I'd like to make my own just for the fun of it.
What's got me confused is how the drive components mount and lock/unlock (ie clutches). Looking at an Ed Byers worm drive for example, you see the following components:
I am trying to understand how this actually drives the telescope. The stepper motor moves the worm gear, which turns the wheel. With the friction clutches engaged, they too would turn, thus turning the attached shaft? However when I see DIY scope builds, the shaft does not appear to be keyed in any way -- is this by design? Circled in the pic above is a small hole I'm guessing for a set screw. Is the shaft simply press fit + set screw and that provides enough friction? Or is there a different way this drive is used?
Looking at my EQ6R below, you can see the worm assembly is attached on the telescope side, not mount side. In this case, with the friction clutch engaged, will the RA axis essentially move around the worm wheel? (ie the worm wheel is fixed relative to the mount side and the telescope side worm gear literally moves around the wheel?)
In general, I don't understand how these gears should interface with the load. When researching harmonic drives, it was fairly obvious that you had a choice between turning a keyed shaft or mounting the load directly on to a flange on the drive (seems like there were drives built with load bearing purposes in mind). With the Byers worm drive for some reason I can't wrap my head around it -- it seems like all the load must be on the shaft but I don't understand how the drive effectively turns the shaft.
I feel like this is a dumb/obvious question but for whatever reason the answer eludes me. Be nice