For the last several months, we have noticed some motion in one or our two telescope piers in the observatory. This is never a good thing.
The piers were built in the fall of 2002. First a nice hole was dug 4 feet down, then a custom made wooden pier made of 2″x4″ wood was set inside the hole and a lot of concrete was poured around it, tamped down and let to set. The 2″x4″s were built with a hollow core, which we poured in sand to help damp vibrations. The floor was not in contact with the pier, also to help prevent pier vibration during walking around the observatory.
So, finally, we had some time in May to empty the place out pull out the carpeting and cut some floorboards to see what was going on.
The floorboards were originally an open deck concept before the observatory building shell was added ontop of it. In addition to the pier moving problem, some of the floorboards were warping twisting and causing an uneven floor.
Turns out the concrete had cracked bigtime.
We were kind of expecting this, so in went a couple of tubes of liquid concrete patch filler, with the pier re-centered and made vertical with shims. The stuff takes 72 hours to cure so in the meantime we
screwed down any floorboard not perfectly flat and started on the next phase.
It gets cold during the winter and our biggest issue was cold feet a lot of the time. So in went a layer of 1/2″ pink rigid styrofoam followed by a 3/8″ layer or plywood. It took some manuevering to try and arrange the fewest number of cuts around the tables, the piers and other infrastructure. The various pieces were leveled when screwing down so now we have a warm-in-the-winter floow that is actually level.
We put the carpet back down again, to help keep it warm and cartep also acts as a dropped eyepiece protector.