Fitting the ZWO EAF to a William Optics GT81 Mk4 , photo guide.

[fifeskies]

Very simple , takes 5 minutes.

No additional parts or tools needed , only the 2 allen keys included in the kit.

 

 

 

Step 1  Remove the coarse focus knob (one with the thermometer). You can use the small allen key supplied with the EAF. 

Place the removed part in a secure bag for safe keeping , you will need to refit it if you remove the motor at a later stage.

 

 

Step 2  Remove the focus lock knob AND the blanking grub screw on the other side. (small allen key) Place in secure bag for reuse if you remove the motor.

 

 

Step 3  Fit the coupler that suits (3rd largest in the 4 supplied in the kit. Remember to match up the first grub screw with the flat on the spindle. There should be a small gap so the coupler does not rub against the OTA body.            (small allen key).

 

 

Step 4  Fit the motor onto the coupler. Remember to match up the first grub screw with the flat on the spindle.

I also made sure both the flat on OTA spindle and the flat on motor spindle were aligned. This may not be necessary but I think it helps them align best.

There should be a small gap between the coupler and the motor housing to avoid rubbing. (small allen key).

 

 

Step 5  Fit the mounting bracket LOOSLY onto the motor using the screws in Pack A , use the washers for good grip.   (Large allen key)

 

 

Step 6  Fit the bracket LOOSLY to the GT81 using another 2 screws from the Pack A , again use washers. (Large allen key)

NOTE: there are several uTube videos showing WO fitting where only the focus lock knob is removed and a single screw connects the bracket. While this will work the bracket runs the risk of moving a little front to back as the motor changes direction , this will ruin accuracy by creating unreliable positioning. The OTA has a blanking grub screw covering the second hole (to keep dust out), Use both screw fix points.

 

 

Step 7  Check alignment and that the coupler is not touching scope body or motor body, tighten all the screws a bit at a time till all are nice and tight. DO NOT OVERTIGHTEN!

A moderate force on all 4 screws is all you need to fix the motor securely.

 

All done and ready to go

 

 

 

 

I placed the removed coarse focus knob and the focus lock/grub screw in their bag into the ZWO EAF box , so if I ever go to remove the motor they are there to put back on.

 

Edited July 7, 2021 by fifeskies

[scotty38]

Same as I did mine apart from the knob is sat on my desk and tells me the temperature in my office 😃

[Adrian J]

Thanks for taking the time to share with others. I saw another YouTube video with only one screw holding the bracket on the GT81 which didnt look right.

[Skyline]

Your fitting is correct. Done the same with my WO73II.