Ric I got them from Bunnings about $12 each. They have roller bearings and are rated at 140kg each. I can move the both roofs at once with one hand with ease.
Have you given any thought to securing the roll off roof against storms ?
The weight of the roof alone will not be enough to stop if being blown off.
See attachment , this is what I will do - eventially - if I ever build a roll off roof shed, I've seen southerly busters here take roofs off car ports that were not properly secured, the wind can generate a lot of lift on a standard shaped roof.
wrt The plywood overhangs at the centre end (see picture 2) straddling the rail-trough . plywood is strong in compression but not in axial tension, would be better and stronger if this was reinforced by steel angle.
Last edited by Ian Robinson; 03-08-2008 at 02:25 PM.
Whoa, that's bigger inside than it looks from the outside.
Plenty of room to move around without having to step over cables and avoid bumping cameras.
Great work.
Yes inside it is 3.3x2.8m or 11x9 feet. The walls are 1.8m high to the 'rail'. The unit inside has been cut into two bits as it was too high. It is just the right amount of room. It has all worked out rather well.
Yes Leon it works like a charm. Here are a few more pictures with the Solarspan installed. It started coming down just after we installed the Solarspan and not one leak. The insulation is great and should stop any radiant heating in summer. Note the 600mm overhang to the north.
A few more images. The roof will be great to stop radiant heat from the Sun in summer as it has 50mm of polystyrene sandwiched between two layers of white colourbond steel.
The whole concept for the design was based on the properties of the Solarspan and the size of the deck we started with. Solarspan is self supporting for up to five meter spans and 500mm unsupported overhang. It is very strong yet only weighs about 10kg per square meter. Both roof structures are about 300kg in total so each wheel has nearly 40kg load on average. The Solarspan holds the roof frames rigidly so you can push them from either side without flexure. The beams at their extremities easily support my weight 80+kg. So there is no problem there Leon.
The total area of Solarspan is 17 square meters. The 600mm overhang on the north side ensures the north wall is shaded from the sun in summer. This wall will be well insulated. Having the central opening at the highest interior point will give very good ventilation from the open decking below in summer if opened without allowing the suns direct radiation in. This will ensure the interior is at ambient air temperature and no higher at all times so no cool down is needed at sunset. I will monitor this to see if it behaves as expected.
The major enemy of your optics is excessive heat. Radiated heat in summer is the most difficult to minimise passively. Condensation can be controlled with adequate ventilation. Time will tell if I have thought of everything.
The whole structure evolved from the drawing very early in this thread. Standard building practises were used where possible.
The design is a mixture of Micks building and cabinetmaking knowledge and my requirements for an imaging observatory with good thermal properties especially in summer. I also liked the idea of a split roof as this gives more protection against wind interfering with autoguiding and pesky neighbours lights.
theodog I dont have detailed drawings and have no intention of doing them. There are no sparrows in Eltham or at least where I am. Feel free to use any ideas. Each situation has its own optimum solution.
Matty P I have not taken one image for two months due to the weather. The next will be a combination of narrow band and full colour taken with the Canon 5DH in the temperature controlled fridge on something dim like the Helix Nebula for MEGA data.
Tomorrow we paint the whole thing white weather permitting. The bits that are not white already that is.
theodog I dont have detailed drawings and have no intention of doing them. There are no sparrows in Eltham or at least where I am. Feel free to use any ideas. Each situation has its own optimum solution.
OK Bert
I'm a builder by trade and have built my own simple roll-off-roof obs so I'm aware of the issues involved in designing and construsting one's own obs.
I'm always interested in others solutions to the obs problem.
Split roof looks good, practical and a great idea.
May it serve you well.
Well done.