[leon]

For those that may be interested, this is really going to show my age.
In 1980, yea 1980, i was just starting Astronomy, there were not many mags around on the subject, an hell, there were no computers either to the general public.
Anyway, I used to get the American Sky and Telescope Mag delivered to my door, and on page 333, October edition there it was (Some Experiments With Curved Bolt Drives), well i thought, I can do that, and did, I still use the one I built in 1982, ready for halleys Comet.

This is how it goes...

Firstly the Formula (R=1,436.5x(n/2nt)
This is where (n) is the turning rate of the drive nut in revolutions per minute and (t) is the pitch of the curved bolt in threads per inch.
For my assembly i used a (one reviluntary per minute motor, and a 3/16th curved bolt, which had to be exactaly 9.5200 inch's from the center of the polar shaft.

With some minor adjustments it came pretty close, and truly, i still use my old drive as we speak.

The actual construstion is really to the individual, it can be as elaberat as you like as long as you keep the formula spot on.

By this i mean, if you use a larger thread pitch, you arch will be larger.

I will try to attach some photo's of the drive, please feel free to talk to me.

Leon