Building my Roll-off-Roof Observatory
By David Rolfe
I hate carry my gear from the house to the yard all the time. I am fairly strong but carrying the mount itself is heavy and awkward. I decided I needed an observatory. I looked around the web and was considering a Sirius, but they were too expensive. Then I nearly bought a XL3 Skyshed pod clamshell, but the wait was too long and people complained about water leakage and the inability to view the zenith. It looked like a good week for a DIY project.
I started out by finding a location in the back yard with the most sky view and then applied to the wife for a building permit. I decided to make the roof slide over an existing water tank to save yard space. I liked the roll-off-roof design as you can see the whole sky when slewing around. Looking at the conventional styles I felt claustrophobic, only seeing a small slit. The additional expense of roof movement for unattended imaging was also prohibitive.
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I drew up plans checking there was enough room for a desk and the full movement of my longest OTA. Then the frame went up.
I used steel for the roof rolling track and gantry over the tank. The remainder was from treated timber pine.
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The roof rollers are automotive bearings that run in lipped channel steel.
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Next step was to pour the concrete floor. I dug out the floor for 100mm of concrete that would be steel reinforced. The concrete beneath the pier was 1 m deep (into the clay layer) and 1 m wide each way (1 cubic meter). This is required to minimise vibration and movement.
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The remaining jobs were to finish the roof (0.55mm colour bond) on a 25x25mm RHS frame and clad the walls. I used fibro sheet on the inside and timber on the outside to match existing features on the house. I built a desk in the corner and some shelves as well. The room has dim-able red lights and power across to the pier.
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Before I put the pier down I installed vinyl flooring to keep the dust at bay and some added insulation bats and foam inside the roof area to stop condensation drips. Then I painted the inside walls a light colour so later I could take flats of it.
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Add an electric lift pier, done!