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DEC balancing issue

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#1 Jganz

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Posted 11 September 2019 - 01:21 PM

Hi All!  So I recently noticed that when I’m balancing my scope in declination, I can balance it fine when it’s horizontal, but when I point it straight ahead again, it pulls to the left like crazy.  My best guess is that my autofocusrt, which is mounted on that side, is throwing it off balance.  I solved it temporarily by mounting another vixen dovetail plate beneath the main one, perpendicular to it, and strapped some weights to it with duct tape and zip ties. It’s hideous, and will eventually fail, but I’ve never guided so well!  Does anyone know of an easier way to counterbalance an asymmetric load like this? I found a counterweight with a side mount that looks perfect, but it’s for a regular dovetail, not a vixen.  Any recommendations are much appreciated!  Clear skies!



#2 macdonjh

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Posted 11 September 2019 - 01:47 PM

I have the same problem with my Parks hybrid Newtonian/ classical Cassegrain: the Newtonian focuser is pretty heavy and makes the scope nearly impossible to balance properly.  If I used the scope regularly, I would install a permanent counter weight inside the OTA, opposite the focuser.  I would likely have to have the weight custom made anyway, so I could size it so it doesn't intrude into the light cone, and would only require one bolt to secure it.

 

A photo of your scope would help...



#3 mich_al

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Posted 11 September 2019 - 01:48 PM

P1010751 20
 
Notice weight offset from center. This worked well on my CGEM for Dec balance.  Later I removed it because it turned out that the mount really needed a bit of bias.

 



#4 Phil Sherman

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Posted 14 September 2019 - 10:11 AM

You can try the following:

 

After you balance in dec with the tube horizontal, rotate it till it's vertical. Rotate the tube in the rings  until it balances again. This uses your guide scope as a counterweight. Be careful the scope doesn't slip in the rings while doing this. Finally, continue with ra balancing.


Edited by Phil Sherman, 14 September 2019 - 10:14 AM.

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#5 emflocater

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Posted 15 September 2019 - 09:15 PM

You can try the following:

 

After you balance in dec with the tube horizontal, rotate it till it's vertical. Rotate the tube in the rings  until it balances again. This uses your guide scope as a counterweight. Be careful the scope doesn't slip in the rings while doing this. Finally, continue with ra balancing.

Very good! This the correct way to balance in Dec when in vertical.

Cheers

Don



#6 macdonjh

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Posted 16 September 2019 - 08:31 AM

 

 
 
Notice weight offset from center. This worked well on my CGEM for Dec balance.  Later I removed it because it turned out that the mount really needed a bit of bias.

 

Clever, I'd never thought of that.

 

You can try the following:

 

After you balance in dec with the tube horizontal, rotate it till it's vertical. Rotate the tube in the rings  until it balances again. This uses your guide scope as a counterweight. Be careful the scope doesn't slip in the rings while doing this. Finally, continue with ra balancing.

Also clever, and also not thought of...  I don't think it would work in my specific case though.  My problem scope is a Newtonian mounted with rotating rings, so it changes orientation all throughout an observing session.  Wish I'd thought of this when I had my C11, though.  It was a little off in declination balance, too.




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