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Disable Meridian safety feature in CGE mount?

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#1 Peter in Reno

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Posted 14 January 2010 - 10:42 PM

I am looking for a good GEM mount for C-8 (don't own it yet). I have narrowed down to CGEM, CGE and Losmandy G-11. So far my favorite is CGE because of high load capacity, nice software (same as CGEM) in hand control and resonable price.

One thing I don't like about CGE is that it won't track past the meridian without flipping. I would like to be able to image at least an hour past the meridian. Because of rear heavy and short tube, the C-8 would be mounted in a position to allow the mount to track past the meridian without the scope hitting the tripod.

Is there a way to open the CGE mount and disable this safety feature? I will always be supervising the tracking so I can make sure the scope won't collide the tripod.

My second choice is Losmandy G-11 and after that is CGEM.


#2 jrcrilly


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Posted 14 January 2010 - 11:02 PM

Is there a way to open the CGE mount and disable this safety feature?


#3 Peter in Reno

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Posted 14 January 2010 - 11:31 PM

OK. I was hoping there would be some kind of switch that could be bypassed.


#4 SleepIsWrong


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Posted 15 January 2010 - 01:49 AM

There actually is a switch that can be bypassed - which should allow you to run the declination motor housing into the RA motor housing about 20 minutes after meridian passage. I surely wouldn't recommend it!




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Posted 15 January 2010 - 09:18 AM

The CGE has hard stops. There is no way to bypass them. There is no way to avoid a meridian flip. One of the few weaknesses of the CGE.

#6 mclewis1


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Posted 15 January 2010 - 12:28 PM

So to be clear, there are switches on the CGE that are checked at the beginning of the initialization sequence ("Switch Limits"). If you put an external switch across the internal switches you could theoretically get the mount to track a bit farther across the meridian.

The stops that Luke mentioned are on the motor housings and have little rubber bumpers. If you used an external switch to by pass the internal ones then you could also drive the scope into those stops. The reason the bumpers are even there is to prevent any damage when the scope is being moved manually (release the clutches and swing the mount axis to it's limits).

Different mounts have different physical characteristics when it comes to bearing, motor and gear housings, and cabling clearances. Then there are the differences in the type of scope on the mount. All of these things affect where any particular mount may get into physical trouble when tracking across the sky. Some mounts have the extra protection in the hardware (like the CGE), some rely on some controller software (slew limits), and some rely solely on the operator.

Personally while I would prefer a bit more "freedom" when tracking and slewing around the meridian with my CGE the annoyance factor is very low. I simply plan the meridian flip a bit earlier than say someone with a G11 ... but we both have to do it.

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