A second stepper is used to make small corrections for errors in polar alignment and uses a ballscrew that has 3/4" of travel. The second axis is driven by a standard stepper controller.
The scope (100 lbs of load) sits flat north to south and rotates 15-degrees east to west. It can fast forward, fast rewind, fast correct, and slow correct (see drawing of indexer / hand controller). A second hand controller is used for the second axis. This equatorial platform puts an axial bearing through the center of Warren Peters' south cylindrical bearing (see Warren's link below).
I would be happy to help anyone that would like a hand building their platform. Just email me and we can work on any problems you are having. . Chuck is the father of equatorial platforms on the web and Warren used his site to build his platform. The jig that Chuck shows is really a great tool to help you get accurate centers on the cylindrical bearings. I am thinking of using his tool and rebuilding my platform to increase the accuracy of the centers.
Build your own equatorial platform with directions from Warren Peters, Chuck Shaw, Dave Molyneaux, or Jan van Gastel - you'll be happy you did!