Some Tips For Construction

The 10-32 threaded brass rod, which drives the upper mount plate and camera, is curved to a 7-inch radius. It is driven upward by a nut epoxied to the bottom of the large gear, which is turned at 1 RPM. Below the bottom plate is a 4 RPM, 3 VDC gear motor, which drives the rod through a 1:4 spur gear set (16-tooth and 64-tooth). Motor speed is adjusted with a variable DC supply (visible above) powered by a 9-volt battery.

I prefered not to install a stop nut on the drive rod below the bottom plate, as called for in the plans. Thus if the drive is inadvertantly left running, it will not stall at the end of the rod, possibly damaging the gears or the motor.