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Maximum weight for CG-4?

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#1 Adrian Lopez

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Posted 21 February 2009 - 02:54 AM

Does anybody here know the maximum weight you can put on the Omni version of Celestron's CG-4 mount? I can't find that information anywhere.

According to the manual for the XLT 120 refractor, the OTA weighs 12.5 pounds, while the counterweights are 7 pounds for the big one and 4 pounds for the skinny one. This is a total of 23 and a half pounds.

I'd like to add a guide scope on top of my XLT 120, but I'm afraid that even without a guidescope it may already be pushing the mount's capacity. I'm considering a Meade 70AZ for manual guiding, but perhaps it would add too much weight to the mount?

Short of getting a stronger mount, what would you advise with regard to guiding on my XLT 120?

#2 watcher

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Posted 21 February 2009 - 07:48 AM

Many on this board believe that the 120 ota with its long moment arm is already too much for the cg-4. I think that weight wise, it's good for about 15 or 16 lbs. not counting counterweights. I think if it were me, I'd do a tuneup on the mount, put some good grease in it, and adjust the tolerences, and give it a try. If it does'nt work, you can always use the 70 az as quick look scope until you can upgrade the mount.

Joe

#3 Adrian Lopez

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Posted 21 February 2009 - 07:07 PM

Thanks for replying. I think I'll call Celestron on monday to see if they have concrete info about the mount's capacity. I also need to know the weight of the Meade 70AZ-AR telescope, so if anybody here knows I'd appreciate the info.

As for tuning up the mount... what kind of grease, specifically, would you suggest?

#4 watcher

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Posted 22 February 2009 - 01:42 AM

Super-Lube is the grease of choice for Synta mounts. As far as a tuneup is concerned, there is a lot of info available for the cg-5, and I think it's similar enough to get the job done.

Joe

#5 Adrian Lopez

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Posted 22 February 2009 - 02:00 AM

Thanks. Other Cloudy Nights posters have recommended this CG-5 tune up page. From glancing at it, it indeed looks similar enough that I might eventually try it.

#6 hudson_yak

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Posted 22 February 2009 - 06:57 AM

Adrian, your CG-4 is new enough that it is unlikely to have the old black grease mentioned in those tuneup pages. They switched to better grease a few years ago.

I don't think there's much question that the mount is not going to be rigid enough for long-exposure AP using the setup you are planning, but that doesn't mean you can't try it anyway.

Mike

#7 Adrian Lopez

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Posted 22 February 2009 - 01:19 PM

I'm now considering the Celestron Travel Scope 70 (400mm focal length) along with a barlow for use as a guide scope, which I'm guessing is lighter than the Meade 70AZ-AR.

OK. So it's likely the grease on the CG-4 isn't as bad as it used to be. Do you think there's no point then in regreasing it? What about smoothing out rough edges in the gear mechanisms? Would that help make it more stable for use in long-exposure AP? I'm not sure I'd like to try that (afraid to damage the mount) as opposed to just re-greasing it, but I won't rule out the possibility.






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