How do you remove knobs off a Celestron pinion ???

[spaceboy]

Hi All

How do you remove the knob of a 130P/ C100ED pinion ??? There is no grub screw, as far as I can make out it's not threaded and it appears there are no caps to flip off. I plan to fit an auto focuser but to do so you have to remove the focuser knob of the pinion. I figured I'd just replace the pinion with an old type from astro boot but they don't have any in

Any suggestions ?? It appears to be the same synta pinion as used on the Celestron C100ED R&P focuser.

[spaceboy]

Surely someone must have tried to fit an auto focuser to a C100ED or 130P ????? no one ????

OK anyone got an old pinion they don't want ???

[brantuk]

They might be the "push fit" type that Celestron have taken to using on some scope/mounts. Have you tried giving them a really good tug?

[spaceboy]

I've tried twisting and tugging. Searching for hidden grub screws and all sorts. I take it if they are push fit they won't work with an AF anyway ???

[brantuk]

Far as I know they still use the same bevelled pinion that you tighten a grubscrew onto. So in theory an autofocuser is directly attachable. It's the inside of the knobs that have changed to push fit (on mounts at least)

[Bizibilder]

Maybe loctite (or whatever the equavelent is) used to glue them on?

[spaceboy]

Thanks guys. I will try warming them up and see if that helps loosen them.

[Kolloth]

I have the Skywatcher 130p on the AZ goto and my mother-in-law got me the Skywatcher auto focuser for xmas (well she gave me the money and told me to get something astronomy related).

The if the Celestron 130 is anything like the skywatcher one then the knobs are screwed onto the pinion directly. I had grab the two knobs and twist in opposite directions fairly hard to get them to budge at all but then one was able to be unscrewed and the auto-focuser fitted.

hope this helps.

[spaceboy]

Thank you Kolloth your a star. I'm always hesitant to go in heavy handed until I'm sure how some thing is fixed.

[Kolloth]

"kak-handed" is my middle name

[A McEwan]

If you managed to unscrew one of the knobs, can you tell me how deepthe threading is on the end of the shaft? I wonder if it would be possible to swap the knobs for aftermarket replacement ones like the Orion Racing Style knobs? I know the original ones are "flared" to match the contour of he focuser body, so maybe the replacements would screw on too far and contact the body~?

Ant

[spaceboy]

Hi Ant

They did come off and I did manage to fit the auto focuser. Just for the record I was not all that impressed. I think on the 130P the combination of a plastic focuser and R&P was just to much to ask of the AF and the motor seemed to struggle for most of the travel.

As regards you question Ant there is roughly 10mm of thread and no taper. While anything can be made to fit with some modification I doubt the knobs you refer to would be straight forward. I doubt the shaft of the pinion is the correct diameter (girth too large) to fit directly into later focus knobs and then you would either have to tap or drill the trunk of the knob to attach to the shaft of the pinion. There are these Orion Classic Brass Set of Focus Wheels | Orion Telescopes which I am assuming would work as a straight swap and certainly look a lot better than the black plastic rubbish that they fitted to the earlier R&P focusers but I again assume they are the same diameter so add no other benefit other than looking pretty.

HTH