Problem fitting EAF electronic focusser

[JimB]

I am new to astrophotigraphy. I have bought a ZWO eaf to fit to my Altair astro wave 115ED refractor.  The focusser is a rack and pinion type. The EAF should be fitted in place of the coarse focussing knob, however the knob does not have a hole with a grubscrew like the other knobs on the fine focussing side. There is clearly a grub screw in the frame of the mounting just by the coarse knob but I suspect that this is for some other purpose rather than securing the knob. As usual there are no instructions detailing what the various grub screws are for. I don't want tp find out the hard way. It may be that the knob is one piece with the shaft and does not come off. I would appreciate any guidance on what the various screws do, and perhaps  some information on wheather it is likely that the knob will not come off from those with experience of focussers in general.

If the knob cannot be removed and I fit the motor on to the slow shaft justhow slow will the focusser move? will it be useable? and can the settings in the software be adjusted to increase the drive speed.

I would appreciate any advice and help, thanks.

[fozzybear]

Maybe fire off an email to Altair to be safe.

[bottletopburly]

Autofocuser can be fitted to fine focuser I have my auto focuser fitted to my Newtonian on fine focus they work fine never had any problems.

[Xsubmariner]

You would be best to fit the focuser to the coarse focus knob.  If you remove the grub screw next to the course knob in your picture, it creates a hole through which you pass to access the grub screw on the course knob ( just loosen it a couple of turns. Then by rotating the course knob you will see a second grub screw through the hole, undo a couple of turns and you will be able to remove the knob.

[JimB]

Thanks for the replies. I have fitted it on the slow motion side and it works. It is quite slow taking 8.5 seconds to move 1mm using the fast setting on the manual controller, or 45 seconds on the slow settings. When I get time I will operate via the computer to see how it runs from there.

The bearing of the reduction gear is exposed so I will have to find a suitable cover to protect it.

I have ordered a pulley and toothed belt so that I can try a belt driven set up. Luckily the pitch of the teeth on the belt match the pitch of the grooves on the coarse knob so the drive should be quite positive. The belt drive would have the advantage that manual focussing can be restored by simply slipping the belt off. Also the drive would be under the focusser instead of projecting out to one side, so would be less susceptible to damage.