What I have at present is a C9.25 on a CG5 mount, but I didn't want the observatory to be limited to that configuration. Therefore, the pier is designed for a CGE Pro mount. Why the CGE Pro? First, I easily found dimensions on the Celestron web site, and I didn't have much luck with most others. Second, the CGE Pro with its "electronics pier" is unusually tall for its class. So I figured if I designed for it, I probably would be able to accommodate anything else that I might get in the future. The pier height is such that, with the CGE Pro, any scope I might mount on it would be able to see over the shutter threshold to within twenty degrees of the horizon.
The pier footing is a couple of inches short of three feet deep. The base, up several inches, is three feet in diameter. From there, it tapers at about thirty degrees up to about ten inches below the surface, where it is 12-3/4" in diameter. From there, it is a uniform cylinder to the top where the 3/4" SS anchor bolts extend up another 4". There are six pieces of 1/2" rebar near the bottom of the hole arranged in a six point star pattern around the base of a central six foot high rebar cage which extends upward to within an inch of the top of the concrete. This rebar cage is wrapped in 6"X6" reenforcing wire to within one foot of the top. The entire pier is cast from 5000 psi Quikrete. The pier was formed by digging a 12" diameter hole almost three feet deep with a post hole digger, then using post hole digger and sharpshooter, the hole was tapered from ten inches below the surface at thirty degrees until it was 36" in diameter at the bottom. This was fairly easy to do in early November, if we tried it now the hole would fill with water and cave in
. The hole was carefully trimmed at the top to fit a 4' piece of 12" Quiktube which is 12-1/2" ID, 12-3/4" OD. Concrete was mixed, three bags at a time, poured and tamped until it was just below where the Quiktube was to start. Pouring directly into the hole from elevated platform was easy. The Quiktube was a snug fit in the hole and adjusted to the proper height and leveled. Pouring continued, but now with a shovel from the top of the tube. Fortunately this went faster than the base. There was much tamping and tapping with a mallet to settle the concrete as the tube filled. When the concrete was up to where the bottom of the J bolts would be the template bearing the J bolts was inserted in the end of the tube.
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