Re: Side-by-side saddle and dovetail suggestions

Christopher Erickson

Balancing isn't that big of a deal. All it takes is a wooden pencil and a few pieces of blue painter's tape.

On the floor, use the pencil to find the center of gravity for each OTA setup. Have your cams, wheels, etc. in place and refractors set to approximate focus.

Mark the center of gravity on each OTA dovetail bar with bits of the painter's tape.

Mount the OTA's on your double/triple/quadruple, etc. tandem dovetail bar.

Center them in their dovetail brackets using the tape marks.

Put the entire assembly on the floor and find the center of gravity for the whole assembly with the pencil and mark it with the painter's tape.

Make sure your mount has enough counterweights on it.

Remove the OTA's.

Mount the tandem bar assembly on the mount.

Mount the OTA's on the tandem bar, starting with the biggest/heaviest.

Check EVERY KNOB THREE TIMES for tightness and security.

Go forth and slew.

P.S. ADM makes extra-long dovetail bars for building up double/triple/quadruple OTA assemblies.

P.P.S. I'll guarantee that none of the OTA's will point to exactly the same point in the sky. Use adjustable dovetail X-Y stages or focal plane X-Y stages for all but the biggest/heaviest OTA.


Roland's suggestion is best. Get another AP mount or three. LOL

"My advice is always free and worth every penny!"

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii

On Mon, Apr 19, 2021 at 12:53 PM mjb87 via <> wrote:
Happy to help if I can. One thing to remember is that the mount balancing gets VERY complicated this way. There is an excellent write-up available from Astro-Physics that explains the various steps required.

BTW, if you have trouble securing the 18" SBS bar -- if Astro-Physics can't supply one in a reasonable time -- let me know. Mine is serving as a paperweight now.


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