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Balancing a Side By Side Setup

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#1 donsinger1

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Posted 03 April 2009 - 10:14 AM

All:

I have avoided using a side by side setup re: fear of flexure during imaging; however, I am going to give it a try on some lightweight gear which will give me some good options, and wanted to know how the heck to balance everything.

Typical setup will be an EM11 Mount with either a C6 OTA w/ 3.3 FR for imaging, and either a MiniBorg 50mm or WO66mm APO guidescope, using PHD.

Thanks,
Don

#2 Joe Cipriano

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Posted 03 April 2009 - 01:33 PM

Don:

1. Lock the Dec clutch, and Slowly release the RA clutch while supporting the scopes. Set the RA axis to home position (CW down), and do a rough RA balance - as long as it's a little CW heavy, you're fine. Don't be surprised if "balanced" is not perfectly vertical - nature of an SBS setup.

2. Lock the RA clutch (axis still vertical), release the Dec clutch, and perform a rough balance on the SBS - slide the SBS in the saddle until the two scopes are balanced in relation to each other. Then adjust each scope so that the entire setup is a little "tail-heavy" (Note: make sure your camera is mounted, and lock the focuser at about the halfway position - you'd be surprised at how much the camera focus position can affect balance with an SBS). Moving the scopes up/down in their rings will change the SBS balance point, so you'll probably need to rebalance the SBS. Continue until balance seems pretty neutral, and a little tail-heavy. Be patient - this can take quite a few alternating tweaks (SBS, OTA1, OTA2) to get right.

3. Recheck your RA balance. If you've got the SBS balanced correctly, the RA should be close to perfectly vertical.

4. Lock the Dec clutch, rotate the RA axis to horizontal, and lock the RA clutch. Release the Dec clutch Slowly while supporting the scopes. Rebalance both the SBS and the individual OTAs, again to a slightly tail-heavy condition.

5. Rebalance RA to slightly "heavy East".

6. Run each axis motor individually, through it's range. You shouldn't hear any oscillating or strain. If you do, tweak the balance in that axis, and check again.

Once your motors are running smoothly, you should be good to go.

HTH

#3 Joe Cipriano

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Posted 03 April 2009 - 05:05 PM

One more note: Make sure you've got the safety stops installed on both the SBS and both OTA dovetails. Almost lost a VC200, ED80, D70, and ST-4 head when I lost my grip while loosening the saddle clamps; the only thing that prevented total disaster was the 1/4-20 safety stop screw on my Losmandy DSBS.

Install the stops.

#4 donsinger1

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Posted 03 April 2009 - 11:28 PM

Thanks very much!! :jump:






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