Hi everyone!
I am posting some images to show my setup
The big pulleys are made from trolley wheels I bought at Bunnings for $2.50 each. I cut the groove with grinder into the rubber wheels so the belt sits in nicely. Since its hard rubber on both pulleys the chance for belt to slip is minimal
Arrow #1 is showing the wing nut with short tube to tighten when everything lines up.
Arrow #2 showing Az wheel with groove cut in
Arrow #3 showing 2 piece of alloy plates with holes cut that way so adjustments can be made, both up and down and left and right.
Arrow #4 showing the pieces of wood I had to put under big wheel to keep the same distance between base and wheel. I put some grease in between so the friction is minimal.
I put piece of fuel hose on encoder shaft (first pic arrow showing the groove i cut). Before that I cut the groove with grinding stone while the piece was spinning on drill, so its centered as much as possible. I used the same way to cut groove into big wheels.
The belts are timing belts from old printer/scanner and are inverted (teeth out).
As you can see, its all simple and rough but it works fine, and the main thing is there is not slip errors at all
Malcolm,
I had the same problem with my dob. Not enough space between scope and base.