Update May 29, 2004

I believe that I have found a reliable concrete contractor. Above: preparing to use a polar-aligned telescope to verify the N-S line that I had previously laid down with a compass. In the foreground is the octagonal form for the concrete pier footing. The minimum depth of this footing from the surface will be 40" and, as seen above, it will extend a considerable number of inches above the surface as well; the idea is to have the top of the concrete pier footing and the concrete observatory floor, which are in the same plane, 1-1/2" above my driveway so that water cannot run off the driveway and into the observatory. Like just about everything related to this little project, this is a bit of overkill, as the driveway does not drain in the direction of the observatory. It is, however, also important for aesthetic reasons for the observatory to be slightly above the level of the driveway; we don’t feel quite right when stepping down into a building.

Above: The pier-footing concrete form as seen from due south -- the string at center being the N-S line. The other string marks the height of the pier footing and the observatory floor. Sitting on the pier-footing form is the Astro Pier mounting hardware. The three bolts form a “V” that points due north.
Below: a closeup of the pier-base concrete form with the Astro Pier mounting hardware in place. The mitered edges are held together with pieces that I cut from scrap on a band saw. The same is true of the bottom of the form. Each screw location is marked, as it will be necessary to split these pieces with a wood chisel in order to remove the form after the concrete has set. The center of the dome will be over the northernmost bolt, six inches north of the center of the pier.
Bottom photo: The Astro Pier mounting hardware as supplied by Le Sueur. They ship this hardware as soon as one orders an Astro Pier so that when the custom-built pier arrives one can have the base ready for installing the pier. (Due to the delay, my pier has already arrived, but I have not unpacked it.) When installed, the bottoms of the three massive j-bolts will point inward to keep them from being too near to the edge of the concrete base.
Next Observatory Construction Page: The Completed Pier Footer
Previous Observatory Construction Page
Observatory Project Introduction

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