The Sliding Roof and Scissor Trusses
Click on the thumbnails for the 640x480 sized image.
September 2002 images
The trusses are pre-built at home, along with the rail bases with the wheels on them and transported out to the observatory site. I used 1x4's for these scissor trusses, a design that is both very strong and lightweight. To ensure that all of them were identical, one was built very carefully, and the parts were then used as templates for the rest of the trusses.
The base frame was installed first, with the rolling wheels on the track. Then the trusses were added one by one attaching with metal angles and screws. Scrap wood was used to hold the top at the correct spacing. This will be discarded later and replaced with a more permanent spacer.
The first initial roll off of the roof ! Until the roof panels are installed, it is a bit shaky, but will firm up greatly later.
End on view of the rolled off trusses. They are all identical except for the first one on the far end, which will have a door in it to clear the schmidt camera when being rolled back.
Next, the horizontal braces are installed, three per side. One at the peak, one at the bottom and one somewhere in the middle. These are what the galvanized steel roofing will attach to.
The sheeting in place. It takes 10 sheets to cover the roof, and each sheet is overlapped by one rib on each side of the panels. A ridge cap is bolted on to seal the peak, and the roof is much more solid now.
An advantage of the offset center wheel design is to be able to roll off the roof the other way about three feet. This makes it easier to install the roofing on the far end, and also allows more coverage of the sky in the rolled off direction, which is normally north.