Saturday, April 23, 2016

Mt Lowe observatory telescope dome

Once the wings were done I moved on to finishing the dome that forms the roof of the telescope room. Prototype pictures appear to indicate that at various times the dome had different types of doors: at one time there were external sliding doors, and later there was one that slid up and down over the opening. I chose to incorporate the latter because that's the open I figured I could make into a working model without too much trouble.
This isn't an exact model of the dome door, just an approximation that I could make work and didn't look too bad. The first job was to install an internal track. I took a length of U-section styrene and cut off one arm to convert it to an L-section. I then cut a thin piece of card to the width I wanted the two tracks to be separated and taped the L-section rails to the card. This assembly was gently pushed into place and liquid plastic glue was used to bond the rails to the inside of the dome. This was a rather tricky bit of installation and I had to think it through and practice holding the various pieces through several mock installations before I actually worked up the nerve to finally glue it in place.
I let this set for a few hours then peeled back the tape and carefully slid out the card spacer. The rails held in place and looked good. All that was needed was to trim the ends.
The door is a strip of 0.010 in. styrene cut to the track width and a little longer than the opening. Friction holds it in whatever position you want.
Here it is slid into the fully closed position....
... and likewise here it is fully open. It slides back and forth quite easily in the track.
The next job was to make a base ring for the dome. This is built up from 4 layers of 0.020 in styrene. The top ring matches the diameter of the dome bottom, the two middle rings match the outside diameter of the telescope room, and the bottom layer matches the inside diameter of the telescope room. 
Here it is all glued together and ready for attaching to the dome.
Before painting some trim strips of 0.010 in styrene were glued to the dome's bottom edge and around the opening. Some 0.020 in styrene was used as filter sections at the top and bottom of the opening. A piece of decorative trim was glued inside the dome at right angles to the opening. That's it! It's ready for painting.
The dome was first sprayed with Tamiya's white fine surface primer and sanded a little when dry. A coat of Krylon flat white was then sprayed on to make the dome more opaque. Finally, a mist coat of the white primer was applied to finish things off.

That's it for basic construction. I'm moving on to building the roofs for the wings - they'll be removable - detailing the interior, and applying the remaining trim to the exterior. Until then, keeping with my random-walk state-of-mind these days, I leave you with another Lowe that I have absolutely no relation to,

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