Platform Stepper Motors.

Thinking of building a platform for my Hardin 12" Dob.

I figured out the dimensions from the yahoo group excel sheet.

I'd like to do a drive system like on the Round Table platforms. I have been cruising ebay for steppers and I'm just not sure what I'm looking for. Seems something around 12V with >120oz torque, 1.8 degrees steps.

Then what do I do for gearing?

I figure my north board is close to a 26" radius for my 40deg latitude and the scope weighs around 80lbs.

Any advice would be welcome.

Jim,

I built a eq platform last year. I never did have time to work out the kinks and am currently rebuilding my dob to alt/az with goto capabilities. The kinks where in my woodworking skills and building of the north and south bearings. The drive system itself worked fine. I use 2 Hurst 3004-001 stepper motors with a drive system including a hand pad with potentiometer for fine adjustments and full speed, stop, and 2x speed. One motor is capable of being plugged in. This took out any backlash if one waits 15 seconds to plug the second motor in after the drive is turned on. I used Dan's site www.geocites.com/birchardvilleobservatory/AstroEQP/
search there for details. I would be willing to sell the two motors and drive system for $100 + shipping. I can send pictures.