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Help with AT65EDQ Focuser Knob?

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#1 Scott Mitchell

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Posted 14 September 2020 - 07:31 PM

Hi everyone, I was hoping someone could help me figure out how to remove the coarse focuser knob from my AT65EDQ so that I can attach a stepper motor. 

 

The picture below shows the focuser, and there you can see the socket in the right-hand knob for the set screw. I have removed the set screw, but I still can't get the knob off. I can get the know to rotate (without the focuser racking in/out) when the set screw is removed, but something seems to be preventing the knob from slipping off. 

 

I'm a little terrified to pull super hard (but honestly I've just been pulling harder and harder to no avail). Anyone have any ideas what I'm missing here?

 

focuser.jpg



#2 syxbach

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Posted 15 September 2020 - 09:42 AM

Let me answer this questionlol.gif  The knob is very tight. You might take the pinion off and remove it carefully. 

 

Yuexiao

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#3 Scott Mitchell

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Posted 15 September 2020 - 11:48 AM

Let me answer this questionlol.gif  The knob is very tight. You might take the pinion off and remove it carefully. 

 

Yuexiao

Thanks Yuexiao. You would certainly have good insight to share there. Maybe I'm just not pulling hard enough. 

 

When you reference using a tool, what are you thinking there? Something to pry the ends of the knob up?



#4 syxbach

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Posted 15 September 2020 - 01:13 PM

I have no idea about the tool. When I disassembled the motor from it before I sent it to you, it was pretty tight, but I still managed to take it out or insert it in. 

 

 

Thanks Yuexiao. You would certainly have good insight to share there. Maybe I'm just not pulling hard enough. 

 

When you reference using a tool, what are you thinking there? Something to pry the ends of the knob up?



#5 Scott Mitchell

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Posted 15 September 2020 - 01:33 PM

I have no idea about the tool. When I disassembled the motor from it before I sent it to you, it was pretty tight, but I still managed to take it out or insert it in. 

OK, gotcha. I'll keep pulling. wink.gif



#6 fmeschia

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Posted 15 September 2020 - 03:33 PM

Double check that you have unscrewed the set screw enough... ideally you may want to remove it altogether. The pinion shaft has a machined flat for the set screw, but it doesn’t get all the way to the end of the shaft, so if the set screw still protrudes a bit into it, the knob won’t come off.



#7 Scott Mitchell

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Posted 15 September 2020 - 06:03 PM

Double check that you have unscrewed the set screw enough... ideally you may want to remove it altogether. The pinion shaft has a machined flat for the set screw, but it doesn’t get all the way to the end of the shaft, so if the set screw still protrudes a bit into it, the knob won’t come off.


Yeah, I've been going on and taking it out entirely (mostly because I was afraid of it randomly falling out and never being seen again).

One suggestion was that there may be a second, interior screw holding the knob in place, but I can't find any evidence of that.


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#8 fmeschia

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Posted 15 September 2020 - 11:17 PM

Yeah, I've been going on and taking it out entirely (mostly because I was afraid of it randomly falling out and never being seen again).

One suggestion was that there may be a second, interior screw holding the knob in place, but I can't find any evidence of that.


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On mine there isn’t any second set screw – but I bought it second-hand, so it might have originally been there.


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