A 10-inch scope became too heavy for me to carry every time I wanted to observe something in the sky from my back yard; I priced some aluminum domes, but due to cost I decided not to go that route. After reading several articles on domes I decided that the easiest way for me to go would be with 2x4's, external plywood and 1/8-inch tempered masonite, the total cost was around $900.00.
All masonite was attached with stainless steel screws, all joints were sealed with silicone caulking and all surfaces were painted with several coats of primer and latex paint.
The 10-inch scope and tripod were set up several different nights in various locations in the back yard to determine the ideal location for an observatory.
An 8-foot diameter circle was marked off at this location. A 6-inch pipe 8-feet long was set in cement with an offset to the south for a Schmidt-Cassegrain fork mount (height above floor level was 41-inches). A round flat plate was welded to the top of the pipe, it had holes bored in the top and threads were cut for the bolts to mount a wedge.
Floor sills were then cut from 2x6's and bolted to the floor. They were cut to 3 1/2-inch by about 24-inches and at an outside arc of 8-feet, a band saw was used for this. Most of the plywood and tempered masonite was cut with two jig saws, because they tend to get very warm. It was later observed that when good hollow-ground blades were used the saws did not get nearly as hot.
Two sets of arcs of 5/8-inch plywood 4 1/2-inches wide were cut to an outside radius of 4-feet. These arcs were glued and screwed together to form a ring (a power screwdriver was used on almost all of the screws on this project).
This ring is the top of the base and is attached to the sills with 2x4 studs.
These studs were set 24-inches off-center and cut to a length that would let the 4-foot wide masonite siding rise up about 1 1/2-inches above the ring. Two of the studs were 30-inches apart and were parallel to each other to form a door facing for a 30-inch wide by 44-inch high door. The door was made from 2x2 framing with masonite on front and back.
Masonite siding was then attached with stainless steel screws. Glue was not used on any of the masonite sections so that, if necessary, they could be replaced easier.
One-inch angle iron was commercially rolled and welded to form a circle with an outside diameter of about 96-inches. This was screwed to the top of the base ring to form a rail for four 5-inch V-grooved wheels.Again two sets of arcs were cut but this time it was 3/4-inch plywood 5 1/2-inches wide cut to an outside radius of 49-inches. These arcs were glued and screwed together to form the ring for the base of the dome. Four 5-inch V-shaped wheels were bolted underneath the base ring.
One more set of arcs were assembled the same size as the base ring for the dome, except rather than a complete circle, two half circles were used. These became the main upright structure for the dome and opening for the shutters. They were parallel to each other and 32-inches apart. They were attached to the dome base with 3-inch corner braces. A 2x4 was used as a cross-brace. It was placed about one foot past the top of the dome on the back side. A temporary brace was also placed about half way between this brace and the base ring on the front side.
A 5/8-inch x 4-inch arc of plywood was glued and screwed to the outside of each of the two upright structures. This arc is a little smaller because it fits flush with the edge of the base ring.
All the rest of the arcs were of 5/8-inch plywood 4-inches wide glued and screwed together. Five upright ribs on each side spaced evenly. Three-inch corner braces were used at top and bottom except at the top where angles were too sharp and hinges were used.
An 8-inch skirt was attached and each panel of masonite was individually fitted and screwed in place with stainless steel screws.
This observatory can be unbolted from the floor and easily moved to another location on a trailer.
