PST Stage 2 Mod - Upgrade

[Merlin66]

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......

Certainly now looks the part!

[axle01]

Nice work old mate, how is the etalon lever connected to the PST Etalon and I’m assuming the mark on the masking tape is a reference guide.

So why didn’t you just motorise the helical focuser, I’m pretty sure Borg make a kit to motorise the helical focuser.

Al

[Merlin66]

Alan,
A small aluminum angle held by heavy duty plastic wire ties around the rubber ring.

I never did see a drive for the Borg, and the SW motor solution is relatively cheap and easy.....

[Merlin66]

The final PST Stage 2 Modification in action...
Looks neat and tidy and works very well......

[Saturnine]

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.

[Merlin66]

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.