Dome build: I [finally] have a plan!


Following discussion on the Cloudy Nights Observatory forum it seemed sensible to put together a plan of future operations. I have to admit that I have not been giving the project's serial progress enough thought. In fact I have been concentrating on getting the dome construction completed before any consideration of actually getting it up on the octagon's walls above the platform.  

The dome's base ring will be built on top of horizontal 2x6s fixed flat on the tops of the octagon posts with lag screws. The large surface area will provide flat and even support for the ring after checking all round with a water level. Shims below the 2x6s are more sensible than fine adjusting the heights of the posts with a saw. No dome rotation wheels will be fitted at this stage.

The telescope and mounting will be removed to safety. A flanged pipe will then be fixed on top of the bare pier to just reach the inside dome height and then carefully centered. This arrangement will act as a strong support and location for the later dome re-assembly in place on top of the octagon.

Completion of the dome's ribs, observing slit and struts must all take place down on the relative safety of the ground. Though I might build some simple supports to lift it to a more comfortable working height. Wooden blocks will have to be used anyway to level the base ring on the sloping and undulating lawn. So an improved means of support makes sense. The dome will need protection form the weather. I seriously considered buying a PVC tent-style garage and selling it on afterwards. The problem is a serious lack of ground space unless the car is parked elsewhere than its familiar bald spot.

The completed dome skeleton will be dismantled into single segments for ease of handling. Each segment will be carried up, singly, and placed on the completed base ring. Weight and physical manageability are vital factors in safe and easy assembly working well above the ground. I shall work as much as possible inside the dome from sturdy, 5' high builder's stepladders with crossbar stabilizers for feet. 

There is a slight problem with the gores/segments being quite narrow so I can't easily reach between them. Though this shouldn't be necessary as it mostly involves clamping and screwing the already assembled segments in place. Which is hardly taxing provided I can easily reach the top of the dome.
The 2' wide observation slit will be wide and parallel offering improved access.

Working down on the ground it is obviously much easier to work from the outside. The dome is much too low to work easily from below when down on the ground. I could work on final assembly from the veranda but the risks of a fall are greatly increased. Though I do own a proper safety harness if I am suitably tethered. 

Once the dome skeleton is completed I shall clad it in its pre-cut plywood panels. Now the dome is nicely stiffened it can be jacked up at intervals onto wooden blocks. Then the wheels inserted between the base ring and flat, 2x6 wall sill. Work on cladding the dome might be easier if it were able to rotate but the advantage is probably minimal compared with having a flat and stable base.


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