Cheap astrophotography dreams

With the unexpected (by me) success of the Canon Digital Rebel in taking wide field astrophotos at relatively long shutter speeds (several minutes), I'm thinking it's time to build a tracking platform for the camera. Typically this has meant a "barn door" tracker. I may just go with that, but one of the problems with a barn door tracker is that it does have some tracking error because it's not a true tangential mount.

I have been toying with the idea of using a microcontroller to drive the steppers, and then I could vary the speed as needed to eliminate any tracking error.

However, it also occurs to me that it shouldn't be that hard to do a true tangential drive with a plywood circle segment. I've seen things on the web of people who have made worm drive gears by applying J.B.Weld to the edge of a wood circle and imprinting a threaded rod onto it.

I will probably still use the microcontroller to drive the stepper motor, because it's just easier and less parts, plus I'll be able to microstep using PWM. But I think I'll just try to build the damn thing first and worry about fancy drive systems later, otherwise I'll never get it done.

I'd like to have this done for the Perseid meteor showers later this month.