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Beefing Up the Atlas

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#1 BKBrown

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Posted 10 February 2010 - 10:57 AM

I am preparing to purchase a C11 Edge HD OTA and want to use it on my Atlas for imaging as well as visual observing. While I believe the Atlas can handle this requirement, I want to make it as stable and rigid as possible. I am currently working on a heavy stabilizing tray to be installed immediately above the leg locking collars; it will be secured with a locking knob just like the small tray via a threaded rod extension to the original equipment. This should help address the weakest link in the system...the tripod. To assist in stabilizing things I plan to operate with the legs fully retracted, allowing just enough play at the bottom to level the mount. Here is where I seriously need some input: in order to elevate the GEM head and OTA I am considering adding the Orion Atlas pier extension (8" of additional height) to improve the clearance and access above the ground. Will I be shooting myself in the foot by destabilizing the mount in adding the additional height? I don't think it will be a problem but am hoping someone can give me some feedback on this idea. In addition, I am adding a CW rod extension to allow me more freedom in adjusting my counterweights. Thanks for checking in, BrianB. :question:

#2 John J

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Posted 12 February 2010 - 10:08 AM

I did a very similar thing to my EQ6. I operate my imaging equipment with the legs fully retracted and added the 8"pier extension. In this configuration the mount is very rigid. I was very pleased with how steady it was with a 120mm F7.5 EON and 80mm F11.3 guide scope with their long moments. The pier extension is very solidly built. It's almost like having an actual pier mount when you can operate with the legs fully retracted. I wish they made a 12" extension though as the 8" just doesn't seem quite long enough.

Another thing I learned when setting this all up too, was to avoid using one counter weight extended way out on the shaft. This can increase the amount of settle time if bumped. If possible use 2 or more weights moved up closer to the mount head. This helps to increase the mass and reduce the settle frequency. It's a pain hauling more weights but if you experiment with the weights you will see what I am saying.

JJ

#3 Takman

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Posted 12 February 2010 - 04:01 PM

I would advise that you get a set of vibration suppression pads. It will reduce the vibrations significantly and I found them invaluable with my EQ-6 and C11.

#4 Bill Cowles

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Posted 12 February 2010 - 06:58 PM

I don't have a C11, but have added the Orion 8" extension for my C6-R. It is not as heavy but much longer, thus more prone to movement. I added the extension to have the diagonal higher and not have to extend the legs. The extension is very stable and I can view standing, instead of on my knees.

Bill

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#5 John J

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Posted 12 February 2010 - 07:50 PM

Takman
I tried the anti vibration pads and they are ok for visual work. I found that their viscous nature allowed movement if there was a brisk breeze or a small gust of wind. For AP direct coupling of the mount to the ground works best for me it seems.

JJ

#6 BKBrown

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Posted 12 February 2010 - 07:50 PM

Great info so far you guys, much appreciated. Takman - I have suppression pads in bound, thanks. JohnJ and Bill - If I may ask, how much do your OTAs weigh with all your gear on board? I'm looking at about 33-35lbs for imaging, with the additional heavy (3/4" birch plywood) stabilizing tray, anti-vibration pads, and racking the legs all the way in do you think this will cut down on vibration enough? My OTA will be much shorter and more compact then the refractors and the weight will be concentrated directly over the mount's head so I think this will work in my favor but I am concerned about the extra 8" of height from the extender (I really want that extra height though!) Am I missing anything obvious here? Thanks for the feedback, BrianB.

#7 Bill Cowles

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Posted 12 February 2010 - 08:01 PM

I agree, you have more weight than my refractor, but not the long OTA and more centered over the mount. I have noticed no difference with the added 8" in stability, just a heavier mass to lift and load on the tripod. The extension is well made and heavy. I only do visual so I can't speak for imaging, you could be pushing it for long exposures.

Bill

#8 John J

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Posted 12 February 2010 - 08:38 PM

Just weighed my imaging OTA's in at 21 LB's. I would estimate another 3 to 4 LB's of cameras and powermates if used. My main imaging OTA os 120mm X 900mm, so about 3 foot long. I use 2 11 LB and 1 7.5 LB counter weights. These are about half way up the counter weight shaft for balance. I have done subs up to 5 minutes with no problems. I use a Canon XSi for imaging and have found that 5 minute subs are not necessary with this camera and scope.

This image was taken using 3 minute subs and only 8 images out of 56 got tossed by DSS.

http://www.flickr.co...381367/sizes/l/

No vibration pads were used as it was a bit of a gusty night. The mount is very stable even with my 3 foot long scopes and wires dangling. I am very pleased with it's performance.

JJ

#9 Bill Cowles

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Posted 12 February 2010 - 09:05 PM

very nice and tight stars.

Bill

#10 Sky Captain

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Posted 13 February 2010 - 03:33 PM

This should help address the weakest link in the system...the tripod. To assist in stabilizing things I plan to operate with the legs fully retracted, allowing just enough play at the bottom to level the mount.


You might try finding a used Losmandy or Meade SG field tripod. I found a Losmandy and machined the top plate to accept the Atlas head. This will be about the closest you can get to a pier in the ground.

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#11 John J

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Posted 13 February 2010 - 06:04 PM

Sky Captain

Well done. It looks like it was designed to be that way. Very handsome unit. I also have looked for used Losmandy tripods and also the Meade giant field tripods. Seems everyone are right proud of them when they go to sell them.

JJ

#12 BKBrown

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Posted 13 February 2010 - 08:01 PM

This should help address the weakest link in the system...the tripod. To assist in stabilizing things I plan to operate with the legs fully retracted, allowing just enough play at the bottom to level the mount.


You might try finding a used Losmandy or Meade SG field tripod. I found a Losmandy and machined the top plate to accept the Atlas head. This will be about the closest you can get to a pier in the ground.


That looks just like what the doctor called for Sky Captain! Did you also custom machine the saddle and counterweight shaft? The CW shaft looks even more robust then I was imagining, although I never expect to exceed 35-40 lbs at any time with my mount (famous last words) maybe I need to think bigger in that department. One of the first things I did the day my Atlas arrived was install the ADM hockey puck and dual saddle so I think I'm good there. Was machining the adapter a huge deal? I do goldsmithing in a shop here at my house, but I don't have a lathe that comes even close to being able to handle that kind of work...is it a very demanding task if I sublet the job to a local shop? Did you create the pattern yourself or is one available somewhere? Is anyone already doing this kind of conversion commercially? As for the Meade Giant Field Tripod, I am seriously considering that as an option. Does anyone out there have experience adapting the Meade tripod to an Atlas? Still, I really like the way the Losmandy mount looks with the Atlas head...like it belongs there. Thanks for the picture it really helps me refine my program. Any other ideas out there? Very Best Regards, BrianB :bow:

#13 Sky Captain

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Posted 15 February 2010 - 02:11 PM

Well done. It looks like it was designed to be that way. Very handsome unit.


Thanks John.

Did you also custom machine the saddle and counterweight shaft?


I machined and sold dozens of the saddle adapters years ago, and the stainless shaft (1.244" diam.) along with the counter weights back when stainless was cheap.

Was machining the adapter a huge deal?



It was pretty easy. Here is a picture of the bottom end.
If you get one and need some help, just PM me. :)

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#14 Sky Captain

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Posted 15 February 2010 - 02:13 PM

Red arrow shows the adjusting pin that was transfered from the Atlas tripod top to the Losmandy top plate.

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