Jump to content


Photo

GM8 RA clearance issues with Gemini2!!! Hello!

  • Please log in to reply
8 replies to this topic

#1 old_frankland

old_frankland

    Mercury-Atlas

  • -----
  • Posts: 2612
  • Joined: 28 Mar 2005
  • Loc: San Francisco Bay Area

Posted 23 December 2012 - 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.lafterhal...erreira_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

#2 Ranger Tim

Ranger Tim

    Viking 1

  • *****
  • Posts: 892
  • Joined: 25 Mar 2008
  • Loc: SE Idaho, USA

Posted 23 December 2012 - 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.

#3 JoseBorrero

JoseBorrero

    Gemini

  • *****
  • Posts: 3170
  • Joined: 04 Sep 2009
  • Loc: Puerto Rico Island

Posted 23 December 2012 - 05:40 PM

you will need a shorter dovetail

#4 old_frankland

old_frankland

    Mercury-Atlas

  • -----
  • Posts: 2612
  • Joined: 28 Mar 2005
  • Loc: San Francisco Bay Area

Posted 23 December 2012 - 07:46 PM

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.

#5 JoseBorrero

JoseBorrero

    Gemini

  • *****
  • Posts: 3170
  • Joined: 04 Sep 2009
  • Loc: Puerto Rico Island

Posted 23 December 2012 - 09:14 PM

or made a double dovetail with the lower one shorter.

#6 Raginar

Raginar

    Fly Me to the Moon

  • *****
  • Posts: 6138
  • Joined: 19 Oct 2010
  • Loc: Rapid CIty, SD

Posted 24 December 2012 - 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

#7 old_frankland

old_frankland

    Mercury-Atlas

  • -----
  • Posts: 2612
  • Joined: 28 Mar 2005
  • Loc: San Francisco Bay Area

Posted 28 December 2012 - 11:05 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


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.

#8 Raginar

Raginar

    Fly Me to the Moon

  • *****
  • Posts: 6138
  • Joined: 19 Oct 2010
  • Loc: Rapid CIty, SD

Posted 29 December 2012 - 07:51 AM

Glad I could help :D 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 :)

#9 RAKing

RAKing

    Fly Me to the Moon

  • *****
  • Posts: 6310
  • Joined: 28 Dec 2007
  • Loc: West of the D.C. Nebula

Posted 29 December 2012 - 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






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics