Relocating the Footing and Pier to accommodate an RCOS Professional Series Equatorial Fork Mount and RCOS 24RC Carbon Truss Telescope...
March 2006. First, we had to remove the 24 inch diameter concrete pier that was installed in 1999. This pier was originally installed for a German Equatorial Mount and was centered in the observatory.
The new 36 inch diameter pier had to be offset for an RCOS 24RC on our Professional Series Equatorial Fork Mount. We dug down to the original footing so we could drill and epoxy steel rebar to the footing and sub-footing (seen on the lower right).
After setting the 1 inch diameter rebar for the vertical supports, we poured the concrete footing, which is isolated from the observatory footing. We used rolled 1/2 inch rebar to tie vertical rebar together.
Once all the steel was in place, we lowered a 36 inch diameter SonoTube into position and built a 52 x 28 x 24 inch form for the top of the pier. This is where the anchor bolts and pier cap will be. There is another 12 inch diameter SonoTube inside of the 36 inch diameter SonoTube making this pier hollow as most modern professional observatory piers are. This reduces weight and thermal mass while leaving a 12 inch concrete / steel wall. The strength and rigidity of any cylinder is determined by the outer diameter - not the core.
We used a 36 x 24 x 3/4 inch thick carbon steel plate for a template / pier cap for the anchor bolts. This steel plate was Blanchard Ground to ensure it was flat and parallel on both sides. We then used a CNC mill to precisely locate and drill the bolt positions. The pier cap and stainless steel anchor (L) bolts were assemble and polar aligned using a transit. Note: we also added an anchor bolt pattern for a Paramount ME Pier (right) as an optional mount, making this pier quite versatile.
This is a view inside of the 52 x 28 x 24 inch form for the pier top before concrete was poured, showing the 1 inch diameter Stainless Steel Anchor (L) bolts.
Using a concrete pump, we filled the form.
Lightening Protection - Very important! This is one of 3 heavy gauge copper grounding cables attached to the steel before we poured concrete. These cables join a grounding ring buried around the observatory.
In addition to the pier being heavily grounded, the clamshell is also grounded by wrapping heavy copper cable over the clamshell and attaching to the grounding ring around the entire observatory. There are two static wicks attached at the top. All of this is designed to decrease the potential for a lightening strike
April 2006. A view of the Pier and Pier Cap after removing the SonoTube and forms.
The pier cap showing bolt patterns for the RCOS Fork Mount (right) and Paramount ME (left).
After allowing the concrete to cure for at least two weeks, we are ready to reinstall the Carbon Steel Pier Cap by use of concrete "dry pack". Dry Pack is low expansion concrete that will fill the 1 inch gap between the original pour and the steel plate. This is commonly used for traffic signals and light poles. It allows the steel plate to be supported by the concrete so it will not "oil can" or vibrate.
May 2006. The steel plate is leveled and the remaining "dry pack" is pressed into place. We now have a stable, flat surface ready to receive the pier.
A total of four 1,500 cfm exhaust fans are located around the base of the support building. These fans draw air from above the the clamshell, over the telescope, around the pier, and then exhaust out of the base.
The telescope (upstairs) is accessed by using a built-in ladder through an attic like trap door.
The clamshell is opened and closed using new motors and electronics from Mike Rice at New Mexico Skies. Mechanics by RCOS.
Complete Observatory Control provided by Mike Rice at New Mexico Skies. Mike's control center provides the following:
- Opens and Closes Clamshell either one at a time or both together. Can be partially opened/closed in any configuration.
- Controls all four 1,500 CFM Exhaust Fans.
- Operates Observatory Lights.
- Additional functionality to be determined.
A fully assembled 24RC and RCOS Equatorial Fork Mount is lowered into the clamshell by a crane as a complete unit. This assembly weighs approximately 2,000 pounds.
The Pier Base is lowered onto the top of the concrete pier and bolted into place. Note the hard rubber fulcrum used for vibration dampening.
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