Dismantle WO Megrez 90 focuser to attach motor?

[rogerg]

Hi everyone,

I have a 6 month old Megrez 90. The type which does not have the tripod bracket. It's focuser is the dual speed rack & pinion style.

I would like to attach a motor to the focuser. With my older Megrez 80 (single speed focuser) I did this very easily by taking one focus knob off and installing a bracket with motor on to the shaft.

With the dual speed focuser, am I able to simply remove the knob from the side that only has one speed adjustment knob and not have the whole thing fall apart? I see the hex screw to undo the knob and perhaps then be able to pull it off, but am a bit weary that doing so the whole focuser and dual speed mechanism may spring apart. I'm not familiar with how dual speed focusers are constructed.

If I can simply take the knob off the single speed side of the focuser then attaching my focus motor should be very easy.

Any advice would be appreciated.

Thanks,
Roger.

[gbeal]

Have you considered attaching the motor to the fine focus shat Roger? It is how the Starlight system works on my F/T.
Gary

[rogerg]

I hadn't considered that ... I assumed that taking the dual speed side apart would certainly be more tricky, but perhaps what you're suggesting is that I can take the slow motion knob off no problem? Or is your Starlight system attached to the knob with it remaining in place?

Thanks,
Roger.

[gbeal]

Roger,
the Starlight one (and the W/O focusers too, they are an Asian clone as far as I can tell), are simple. A hidden setscew is all that holds the knob on the shaft, and once the fine focus knob is removed, the shaft is left ready to attach the motor to. Try this http://www.starlightinstruments.com/downloads/InstallationStepperMotorAttachment. pdf it will show how their system fits.
Gary

[rogerg]

Thanks Gary, interesting to see inside the assembly. My focuser is different to that one, but I bet the dual speed mechanism is very similar if not the same.

I will probably give it a shot tonight.

[rogerg]

Well I have taken the focuser apart enough to see it is just as easy as my old Megrez 80 (single speed focuser) to attach a motor to it.

I will attach the motor on the side with single speed control. This means when the motor is not attached I easily retain dual speed manual focusing with the other side.

I think a small piece of aluminium with three holes drilled and it will be all done.

Thanks,
Roger.