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Focuser Upgrades/Tricks for CPC 925 EdgeHD?

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#1 BluNos

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Posted 18 April 2024 - 06:46 AM

The scope is used almost entirely for visual use, and the occasional quick smartphone snaps with an eyepiece adapter - it seems like it would be nice to get a bit better fine focus control.

 

I've seen some posts about install issues and whatnot with the Celestron motor focuser, which maybe also seems like a bit of overkill for my purposes.

 

I also found a few posts about putting a clothespin on the knob?  I guess the extended leverage would improve things?

 

There was another post about making a larger focus wheel/knob from hardware store parts etc that fits over the stock one, which I think was on a C11, but there doesn't seem to be the same amount of room around the knob on my 925 (I've got the Baader quicklock setup with the adapter for the visual back).  I've got a buddy with a 3D printer so I was even thinking about seeing if he can come up with a press-on/slip-on knob wheel with bit of knurling/finger notches or whatever maybe.  And I could get fancy with my own colours, logos, hahahhaah.

 

What else have others done?  Other than the motor focuser, are there other upgrade options worth looking at that are relatively simple to install? 



#2 norvegicus

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Posted 18 April 2024 - 07:04 AM

I have a 3D printed big knob.  Works great.  There isn't a lot of room so the dimensions have to be just so.

 

Also ScopeStuff sells one:  https://www.scopestuff.com/ss_foc9.htm


Edited by norvegicus, 18 April 2024 - 07:06 AM.

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#3 BluNos

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Posted 18 April 2024 - 07:35 AM

Nice, any chance you've got and would share the 3D print file for yours?  bow.gif



#4 weis14

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Posted 18 April 2024 - 07:54 AM

I have an old C9.25 and upgraded the focuser to the Starlight Instruments Feathertouch focuser.  It really works well and is easy to install, but it isn't cheap.


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#5 mlord

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Posted 18 April 2024 - 08:15 AM

Just google "thingverse celestron focus knob" or similar.


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#6 BluNos

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Posted 18 April 2024 - 08:54 AM

Awesome, I'm pretty new to the 3D print community resources as I've only ever had one or two car parts made up by my friend with the printer that were shared designs going around on the car group owners forum.  Some good stuff there which I am sure will do the trick even if a little bit of tweaking is needed to fit.



#7 deansjc

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Posted 18 April 2024 - 09:26 AM

You could DIY for mere pennies a 1.5" or so disk with a 7/8" hole from a piece of .25" foam board or wood.  The key is to insert a stiff wire into the perimeter a 6" or so stiff bit of wire.  Voila.  Place over existing knob after achieving rough focus so as to have a placement that is clear of obstructions.  This will provide superior focus control...equivalent to a 12" diameter focus knob!  (Hole diameter of 7/8" is for an 8" SCT.  The SE focuser knob is slightly tapered which makes the fit easy to achieve.)

 

Don't have or want to make those bits?  A second method is to bend a 9" or so long bit of coathanger wire to create a round loop at one end that is just smaller than the diameter of the knob.  Expand the loop manually to place over knob as stated above and release to afix securely over the focusing knob.  (Tape over the sharp end  of the wire for comfort and safety.)

 

Just make sure to select low mass materials so that the arm does not rotate the focuser. 

 

Again. you're done.

 

Happy focusing.

 

 

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Edited by deansjc, 18 April 2024 - 11:41 AM.

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#8 norvegicus

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Posted 18 April 2024 - 09:48 AM

Nice, any chance you've got and would share the 3D print file for yours?  bow.gif

I would be happy to if I had one.  I bought mine before I had a 3D printer, from a CN user who was selling them at the time.  I don't remember who that was and CN soon after locked down the classifieds for such things.


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