ZWO EAF Adapter Plate for GSO Ritchey-Chretien Telescopes

Needs 2x M3-.50x20 screws

ZWO's Electronic Automatic Focuser doesn't officially support the GSO RCs sold by iOptron, Astrotech and others. The bottom plate of the focuser is curved, but this adapter fits nicely into the curve for a flat surface to attach the mounting plate. Here are my steps for attaching the EAF:

1. Print this adapter. I used 0.15mm SPEED setting in PrusaSlicer. The exact settings shouldn't matter too much. This is just sitting between the bracket and the focuser

2. Replace the tensioner screw (bottom middle of the focuser) with one of the tiny anti-loosening screws from the EAF

3. Install the flexible coupling on the coarse adjustment knob.

4. Flip the plate on the EAF L-bracket using the two screws on the short end. The grooved side of the long edge of the L-bracket should be on the same side as the short edge.

5. Remove either the front two or back two screws on the focuser adjustment knob assembly

6. Place this adapter and then the mounting bracket on the focuser. Use 2 M3-.50x16 screws (not included with the EAF, you'll need to buy these separately) to attach everything together. The screws should be in the first and third slots of the bracket, which inline with each other. Note that this does make the bracket slightly offset from the center. The tensioner screw is still accessible with the ball head hex wrench in the EAF box

7. Insert the EAF axle to the coupling and attach the EAF to the bracket. Because the bracket is offset from the center of focuser, the EAF should be at a slight angle to align the EAF axle with the focuser axle.