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Do I need another counterweight?

Celestron equipment astrophotography
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#1 johnnh5126

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Posted 28 May 2020 - 10:36 AM

I set up my Meade LX-85 with my Celestron Rasa 8.  When I went to align the scope the scope side slid down like it was heavier than the counterweight even though the motor was running.  I tried moving the counterweight out more, but the same issue.  I dont want to destroy the gears.  Is the included counterweight enough, or do I need to add or maybe replace it?



#2 Hesiod

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Posted 28 May 2020 - 10:57 AM

If, with open clutches, the mount moves in AR and is heavier on the side of the tube then you need more weight (or to move the existing CW farther*) to achieve balance.

If this happens even with tight clutches and while tracking, then you risk damages to the mount's gears as the system is wildly unbalanced

 

Ideally the mount should be perfectly still even with fully released clutches even if, depending on the system's geometry, this may not happen at every possible point: in such case I try to have the mount well balanced for the range of movement  am interested in (typically the 30-60° arc the mount has to cover to track the object)

 

 

 

*I opt more often for this solution because implies moving less weight, but having more weight closer to the axes' intersection may save some other issues


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#3 DSOGabe

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Posted 28 May 2020 - 11:54 AM

If you are at the very end of the CW bar and it's still occurring then you will need another CW.



#4 sunrag

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Posted 28 May 2020 - 08:52 PM

If you can add a small extension bar to the end of the CW bar, you can get a bit more balancing range. I installed a M6x75mm screw to the end of the CW bar (where the usual safety screw is attached). With this, I can either move down the main CW another 75mm down or use a second, smaller CW in the 75mm extension. (I have a Celestron CG-5 which takes a M6 screw, your Meade LX-85 may take a different screw. My smaller Meade EQ-1 tripod also uses M6 screw). You also need large fender washers to hold the CWs since the safety screw has been removed and the hex head of the M6 screw is not large enough to serve as safety stop.

 

Another trick I learned is to remove the heavy 2" diagonal and eyepiece before slewing the telescope. Not only does this reduce the load on the motors considerably, it also eliminates (or reduces) collision hazard with the tripod legs. 


Edited by sunrag, 28 May 2020 - 08:56 PM.


#5 johnnh5126

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Posted 28 May 2020 - 09:29 PM

I'd rather just add another counterweight.  But I dont see anyone else using one with the LX85 & RASA 8 with more than one counterweight.  Plus im not sure if it would be too much weight.



#6 johnnh5126

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Posted 28 May 2020 - 09:49 PM

But what confuses me is that the LX85 specs says that the load capacity is 33 lbs, and the RASA 8 is only 17 lbs, so the weight  should be ok, no?



#7 sunrag

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Posted 28 May 2020 - 11:00 PM

Yes in that case your mount should be able to handle it. But check the weight of the Counter weight. It may be too small (i found that my CW was only 7.5lbs whereas the spec’s said 11lbs).

It helps to lock one axis, and balance the other. Then reverse the process so that both axes are simultaneously balanced. It was an iterative procedure for me. I first practiced with lighter telescopes and was able to balance in one iteration. Then when i put a heavy telescope i had to repeat 4 or 5 times to get it to balance.

#8 Waldemar

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Posted 29 May 2020 - 02:44 AM

But what confuses me is that the LX85 specs says that the load capacity is 33 lbs, and the RASA 8 is only 17 lbs, so the weight  should be ok, no?

The load capacity specs don't say anything about the supplied counterweight... most of the time the counterweights are not by far enough.

 

I set up my Meade LX-85 with my Celestron Rasa 8.  When I went to align the scope the scope side slid down like it was heavier than the counterweight even though the motor was running.  I tried moving the counterweight out more, but the same issue.  I dont want to destroy the gears.  Is the included counterweight enough, or do I need to add or maybe replace it?

Balancing is critical for any mount. Do not assume it is balanced, because the supplied counterweight is on it. Do the balancing procedure and make sure the mount is balanced in all directions. Randomly moving counterweights is not a good idea...
If you do not know how to balance your mount, check YouTube. Enough balancing videos are available.


Edited by Waldemar, 29 May 2020 - 02:46 AM.



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