I've been using the Borg helical focuser on many PST Mods over the past few years. Very effective, but manual operation.
I've just upgraded my Stage 2 PST Mod, which has a front adaptor which allows the assembly to be mounted on the TS102/1100 or behind the SM60/ED80 as a double stack. I also fitted a Lunt Crayford focuser and added a SW motor.
A significant improvement - I can now precisely focus remotely.
To improve the aesthetics, I also added a covering "tube" on the PST etalon, with a lever adjustment......
Hi Ken
Nice work on the Stage 2 and focuser. Hope you don't think I'm copying you but I'd actually bought some XML belts and various toothed sprockets a few weeks ago to make a motorized focuser set-up for my refractors, using an servo motor for the drive unit. Initially tried using O rings for the drive belt but they stretched too much and not enough surface contact area so not enough positive drive. Just need to do some machining and fabricate a bracket that is adjustable.
Yeah,
I find the XML belt, especially when applied to the 10:1 focus knob, is a great solution. It can easily be slipped off the knob for manual adjustment and quickly replaced.