A Question for the G11 Owners

[leon]

Hi Guys.

Could I please ask about the Alt and Dec clutch locking devices on the G11 mount.

Obviously when the scope is being used they are very secure and It is said that you cannot damage the clutches if you over tighten the locks.

When I have finished for the night, I tend to release the clutch knobs to release the continuous pressure that would be applied if they were left locked.

My question is, is this necessary, or dose it not matter if they, the locks are left for extended periods of time in the locked position.

Many thanks for your anticipated response.

Leon

[Omaroo (Chris Malikoff)]

Leon - I don't do my clutches up very tight at all - even when guiding. I set them so that they grip and hold their position without moving, but that's it. The clutches will still transfer rotational force to both axes without them needing to be tight if the scope is properly in balance. I can move the scope against them with hardly any effort at all - but then again I don't run a Gemini system so I won't lose alignment if they are moved after alignment.

I can't answer you question directly because I haven't pulled my clutches apart to look at them - the mount is still brand new - so I'n not sure of the materials involved. I guess the clutches should be Ok if left tight - but tight is a relative term. Does your G11 slip badly or something if you don't really tighten your clutches?

If you haven't already, you can fit your mount with a set of Losmandy encoders and you can plug these into the Gemini - then even if you do push-slew the mount in either axis the encoders will tell the Gemini what's going on - so you'll never lose star alignment or position.

[leon]

Thanks Chris, in answer to the fact if my G11 slips, the answer is No, as it is pretty well balanced, and like yours is easily moved with a finger tip when loose.

I have the feeling, that I maybe over tightning to be honest, so I will give it a shot with less tension.

Also Chris, I'm not fussed with the alignment really, as I usually just do a one or two star align and work from there for the night, and often move the scope out of alignment.

I was just wondering if it would be best to slacken off when not in use, so to speak, thanks for your response.

Leon

[RayOfLight]

Hi Leon,

Have been using the G11 for imaging, and whenever an exposure is about to be taken, I would increase the tightening pressure on both RA and DEC clutches. During drift alignment process, they would normally be a little "looser". When it is not used, I would loosen the clutches generously. Mount has been fine all this while for the past eight years. No slippage. After upgrading the worm to the high precision one, it works even better.

[Bassnut (Fred)]

umm, I notice you guys use small refractors. I have a 12" SCT and a heavy cam on the G11, and found I need the optional handle set to get the clutches as rock hard as I could to stop slipping (especially with even the slightest accidental nudge). I almost never slacken them off (only to rebalance etc) and they are still fine.

And Chris, the standard Gemini encoders are on the motors, not on the output shafts, so if the clutch slips, you lose position.

[allan gould]

Fred
Make sure there is no grease on the surfaces of the washers and then you can tighten up the clutches with no slip. I adjust mine so that just in case the mount suffers a brain f@rt and goes slewing where it shouldnt then the mount will slip on the clutches and do no damage.

[leon]

Many thanks for you responses, much appreciated.

Leon

[Omaroo (Chris Malikoff)]

Originally Posted by Bassnut

And Chris, the standard Gemini encoders are on the motors, not on the output shafts, so if the clutch slips, you lose position.

You're right Fred - I should have said "additional shaft encoders". These act as an adjunct to the standard set and plug into the Gemini through a specific encoders port, and do allow you to loosen your clutches and push to a new location without losing your positional data. I'll be using a set of these in conjunction with an Argo Navis shortly as I opted not to have Gemini.