[OzEclipse (Joe Cali)]

Many years ago I built such a structure to hold mount without OTA. I was offered the opportunity to bolt down a pier at Arthur Page's then Mt Tamborine observatory. I built a lightweight box frame out of 50x50mm Oregon pine about 700x700x1600mm(h). I then ordered 4 pieces of 22 gauge galvanised iron from a sheet metal shop. each piece was the size of the side of the structure but each had 90 deg fold on the edge with a 50mm strip on the fold. These returns were all overlapped to prevent ingress of water at the corners and added a lot of strength and stiffness to the structure. One side was removable and the frame at the base on that side was on a hinge with a shed bolt catch.

The sheet metal shop made me a square cap for the structure with soldered seams and 50mm vertical sides. It was a little oversize allowing the removable side sheet to be inserted and removed from under the cap. I made the whole thing as an 18 yo with minimal construction skills. Mt Tamborine was a high rainfall zone, the structure kept the scope dry. Two loxons were drilled into the slab and two 1/2" bolts held the whole structure down in the face of sometimes very high winds. There were two substantial handles on the sides which made it easier to drag off and away from the mount. Two if the cross braces were at "observing seat height." I had a shelf I could insert in there and sit inside it, shielded from the wind during hours of manual guiding that was an unavoidable part of AP in the early 1980's. In the 2nd photo you can see it with shelves inserted.

Were I to build it today, I'd use much lighter weight aluminium siding or fence panels, readily available and cheap.

Joe Cali