[asimov (John)]

Hi.

Just a quick post to show you the tracking setup I came up with to drive the 12.5" newt.

The radial arm is constructed out of galvanised sheet metal & tack welded together. It is 209mm long & attaches to the RA axis. There are 2 lengths of 1/4" X 20 TPI all-thread, curved to the radius of the arm & tacked in position. Attached to the 1.8 step motor shaft is a piece of the same all-thread. With this reduction, it is necessary to have the motor rotating exactly 1 RPM to track at the correct rate. The close up of arm & stepper is just a representation of the setup used..(a previous prototype that failed)

She's a rough set-up as you can see, but it works, & works good. Total cost was about 10 bucks for the all-thread. & my labour if you want to include that. The stepper & controller were free. Same for the battery, which was a 12V car battery from the local dump cut in half to make it 6V.

Still some fine tuning to be done at my leisure.