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Equipment Discussions >> Mounts

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old_frankland
Carpal Tunnel


Reged: 03/28/05

Loc: San Francisco Bay Area
GM8 RA clearance issues with Gemini2!!! Hello! new
      #5585660 - 12/23/12 01:51 PM

I'm just now installing the Gemini 2 on my long suffering GM8 mount and was more than alarmed with the clearance issue between the dove tail and RA motor when the scope is aimed at the zenith. I guess I should have anticipated this issue seeing how the drive motors hang out roughly twice the distance from the mount than the older stepping motors.

Not having access to the zenith and a good part of the meridian from the east side of the mount is a major problem if you are doing tempral timelapse videos of the sun or planets. Just as important is the potential of destroying the drive motor while manually moving the scope.

http://www.lafterhall.com/RA_clearance_Gemini2_ferreira_001.jpg

This is most disappointing and I will likely be returning the Gemini 2 and go back to my stepping motors. No other mount in the same class has this issue. Losmandy what were you thinking?

Thanks for any input.
Jim


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Ranger Tim
scholastic sledgehammer
*****

Reged: 03/25/08

Loc: SE Idaho, USA
Re: GM8 RA clearance issues with Gemini2!!! Hello! new [Re: old_frankland]
      #5585956 - 12/23/12 05:06 PM

We need one of those extra spacers like I've seen for the G11. Same issue here with mine except there are regular motors on mine, not Maxxons.

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JoseBorrero
Post Laureate
*****

Reged: 09/04/09

Loc: Puerto Rico Island
Re: GM8 RA clearance issues with Gemini2!!! Hello! new [Re: Ranger Tim]
      #5586012 - 12/23/12 05:40 PM

you will need a shorter dovetail

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old_frankland
Carpal Tunnel


Reged: 03/28/05

Loc: San Francisco Bay Area
Re: GM8 RA clearance issues with Gemini2!!! Hello! new [Re: JoseBorrero]
      #5586181 - 12/23/12 07:46 PM

Quote:

you will need a shorter dovetail




I can move the tube rings down the dovetail for a bit more clearance, but that doesn't help with my solar refractor or C9.


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JoseBorrero
Post Laureate
*****

Reged: 09/04/09

Loc: Puerto Rico Island
Re: GM8 RA clearance issues with Gemini2!!! Hello! new [Re: old_frankland]
      #5586274 - 12/23/12 09:14 PM

or made a double dovetail with the lower one shorter.

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Raginar
Post Laureate
*****

Reged: 10/19/10

Loc: Rapid CIty, SD
Re: GM8 RA clearance issues with Gemini2!!! Hello! new [Re: JoseBorrero]
      #5587658 - 12/24/12 07:17 PM

The MI250 has a similar problem. One fix was the addition of a declination spacer that allows you to adjust for the RA motor...

Maybe you could find a machinist in your area to produce something similar?

www.mi250.com


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old_frankland
Carpal Tunnel


Reged: 03/28/05

Loc: San Francisco Bay Area
Re: GM8 RA clearance issues with Gemini2!!! Hello! new [Re: Raginar]
      #5593515 - 12/28/12 11:05 PM

Quote:

The MI250 has a similar problem. One fix was the addition of a declination spacer that allows you to adjust for the RA motor...

Maybe you could find a machinist in your area to produce something similar?

www.mi250.com




Yeah, after looking at the mount, turning a short extension is pretty straight forward and should get me access to the meridian from the east side of the mount. Good call.


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Raginar
Post Laureate
*****

Reged: 10/19/10

Loc: Rapid CIty, SD
Re: GM8 RA clearance issues with Gemini2!!! Hello! new [Re: old_frankland]
      #5593877 - 12/29/12 07:51 AM

Glad I could help Just make sure you follow his instructions, apparently you need to re-adjust your worm gear tension to prevent damage.

Good luck! And post pictures for everyone when you're done


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RAKing
Postmaster
*****

Reged: 12/28/07

Loc: West of the D.C. Nebula
Re: GM8 RA clearance issues with Gemini2!!! Hello! [Re: old_frankland]
      #5594314 - 12/29/12 12:26 PM

Yes, it's tight in there and that is why the GM-8 comes with that tiny dovetail saddle.

A 1/2 inch spacer would be a great idea and I wish I had access to a lathe.

Cheers,

Ron


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