Best method for balancing SBS setup?
Posted 04 May 2011 - 12:12 AM
I'm wondering, should I mount each scope alone on the mount first to determine and mark it's balance point on the individual dovetails, then put the 2 together (how the were balanced individually) and try to move them around as a unit?
I'd appreciate any tips from my SBS brethren.
Posted 04 May 2011 - 12:25 AM
Posted 04 May 2011 - 12:49 AM
When you position your DEC axis horizontally and release the DEC clutch, the scopes will rotate so that the CM is below the DEC axis and this will tell you which of the two directions is not balanced.
Hope this helps a little.
Posted 04 May 2011 - 10:52 AM
I think what I'll try to do is get the C14 balanced in DEC, then add the 98FLT to the mix and try to maintain balance.
I'll keep everyone posted.
Posted 04 May 2011 - 12:49 PM
Every scope combination has a balance point, you just have to find it. Even taking 10 or so iterative steps I get very close to balance (the AP mounts handle a bit of unbalance just fine) in about 15 minutes.
When starting out I bear hug the biggest scope just in case things go flying when I release the clutches.
Posted 04 May 2011 - 03:26 PM
If you're looking for a good method, try this:
That pictorially describes exactly how I do my SBS setup of a C11 and FSQ106 (and sometime soon may swap one out for the AT6RC...)...
as long as you're methodical, it works fine.
Posted 04 May 2011 - 04:40 PM
Posted 04 May 2011 - 05:45 PM
Shawn, from what you describe it looks like you start with the C14 too far from the center. Since it is so much heavier, it should be almost at the center, and the WO to the side. C14 should be as many times closer to the center as it is heavier.
C14 is about 45lbs and WO 98FLT is 7lbs. So C14 should be 6.5 times closer to the center. If the OTAs are 15 inches apart then C14 should only be 2 inches away from the center, and the refractor 13 inches away.
Posted 04 May 2011 - 09:40 PM
Start with everything off of the mount. But have the telescopes as close to how you plan on using them (eyepieces and diagonals in or cameras)
Find the balance point of one of the scopes using a round object under the rail. A ball point pen or similar works well. Mark the balance point with a wax pen or tape. Do the same for your other scope.
Place both scopes onto your sbs setup with their balance points centered over the dovetail bar of the sbs. Now everything should be balanced fore and aft.
Take your sbs bar with both scopes attached and find the left-right balance point using the same method as above. Mark the sbs dovetail bar and place it on your mount with the balance point directly centered over the dec.
Move the ra counterweight as needed and you're good to go!
I had great luck doing it that way. It sounds complex but I used to be completely mobile and could get it balanced in well under 5 minutes. Let me know if that works out for you
Posted 05 May 2011 - 01:09 AM
Also, I always felt uneasy about putting all the expensive and fragile stuff like a binoviewer on the scope, and then releasing the clutch and sending it all for a spin.
I'l give it a try next time I set up.