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.

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.

The roof rollers are automotive bearings that run in lipped channel steel.

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.

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.

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.

Add an electric lift pier, done!