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Mount balancing in 3D?

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#1 Hilmi

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Posted 15 January 2013 - 07:11 AM

I'm having difficulty balancing my mount in Declination.My equipment is an 8" SCT with a motorized moonlite focuser and STT-8300 camera with it's big as a barn door filter wheel and telrad. I set it up so that it is parallel to the ground and move it backwards and forwards till it balances. Now when the scope points up it won't stay up, so it's obvious it is not balanced to the left and right. Is this significant enough to impact guiding performance? If it was a scope in tube rings, I would have been able to rotate it in it's rings, but with an SCT, you cant rotate the scope. I am clueless as to how to fully balance out the DEC axis in all directions.

In RA axis, it's pretty straight forward for me and I am clear about how to handle that axis. It's only declination which drives me nuts.

#2 Thomas Karpf

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Posted 15 January 2013 - 08:10 AM

I imagine testing will show you if it's enough to impact guiding performance; we have insufficient data :).

Add weight to the side that's clearly light, as far from the balance point as possible. What to use for weight, how much, and how to attach it is left as an exercise for the student. I would imagine that several ounces of magnets (assuming the tube is steel) would be sufficient since your scope was otherwise balanced.

#3 MikeML

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Posted 15 January 2013 - 05:39 PM

Find a copy of All About Telescopes, there's good info on balancing in both axis
http://www.scientifi...copes-book.html

#4 Phil Sherman

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Posted 15 January 2013 - 10:32 PM

The way to balance out the off center weight on top of the mount is to make the counterweight off center.

Drill a hole and tap it on the perimeter of the counterweight. Attach a shaft and another small counterweight that can be adjusted to balance out the off center mass of the scope and camera gear. You may need to add a second screw lock on the original counterweight to keep it from spinning on its mounting shaft.

Phil

#5 EFT

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Posted 16 January 2013 - 09:53 AM

Perfect balance in DEC is not going to be necessary nor desireable. If you get perfect balance and have gear backlash, then the mount will tend to bounce around in the backlash area. You really just need to get it close so that it does not strongly influence the RA balance. The one thing you may want to do, if you haven't already, is add some wieght to the front end of the scope (attached to the dovetail) so that you don't have to mount it at the very end of the dovetail. That may also make things a little easier. All the off-center wieghts on the SCT will always make perfect balance very difficult to achieve.

#6 Hilmi

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Posted 16 January 2013 - 10:20 AM

Many different views and ideas. Wont be fiddling with the ballance tonight. My mount tracked well for the first time last night. I dont want to spoil that






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