At the risk of yet another Observatory-Building thread, I thought I might throw in this idea that I am pursuing with my own project. I am not a "spring chicken" any more and so heavy construc tion projects are out. I therefore went looking for a relatively simple ready-made solution to the question about how to construct a Roll-off observatory. PODS are out because I want this to house a big Dob.
I had planned a 5 x 4 metre design in order to accommodate both a 16" Dob and a Meade Maksutov about the same size as an 8" SCT. The Dob needed a working radius of 2.4 metres and the Mak another 1.5 minimum so 5 metres was a must along at least one side. By the time this option presented itself, I had already dug the holes for the Dob Slab and the Mak Pier and poured them both; and also dug the holes for the supporting saddles for a raised floor.
By chance, I was driving near Gatton one day and saw one of the usual "Shed" shops and thought, 'what the hell, I'll go in and have a look'. I came across these things called paddock shelters for horses. They are 4100 x 4200 and have an optional 1500 extra length awning - meaning with a bot more steel and a bit of welding, it can be rejigged to my required size.
The beauty of these sheds is not their size, though, but the way the walls are constructed. From the picture attached, you'll see that the bottom 1200 of the walls is lined with heavy conveyor-belt rubber sheeting - so horses can happily kick the #$@% out of it. And the top section of the walls drops into the bottom and is then scrwed and braced into place. But with a bit more 50x50 2mm gal box section, the top section can simply be put on a frame with a few rollers and can happily slide off on a bit more gal box section and voila - a ready-made Roll-Off. The open wall that would normally be the point of access for Dobbin can be framed up to the same height and the top section likewise with a saloon door arrangement in both top and bottom for full-height access.
The top and bottom wall panels and roof sections come pre-built and simply bolt and brace togehter and also onto a slab or as I plan to do it - a raised floor.
At 1200 the walls are probably a bit low when you think about wind and the like but this can be accomodated some external flaps that fold up on all sides as a wind barrier. And to deal with the height of the scopes inside - particularly an equatorially mounted Mak on a pier, one wall will also have to have the top section hinged so it can be raised when (before) the roof is rolled away. Not a big deal.
Cost - even with a discount, it cost me $3400 but that is OK with me because it significantly reduces the problems of an old stiff back and working alone out in a fairly remote bush location to get this Obs built.
For anyone interested, the pier is a piece of 1700 of 150mm dia steel pipe with about 8mm walls filled with concrete and the top plate is a 25mm thick steel pipe connector with a bunch of pre-drilled holes so I can pretty easily build an adjustment plate on top. The pier is 600 in-ground and has a 400 cube on top of that so it sits in a metre of concrete. The pier cube and the Dob slab are both about 350 above ground level and will be about 150 above floor level so I expect to have pretty darn good horizin access for the Dob - something you don't generally get with higher walls. The big triangular slab has 3 anchoring bolts at each corner to take a very specific Dob base and will hold it like a vice.
