Looks like a real work of art Chuck -- nice job! ETA for completion...? --- Chuck Hards <chuck.hards@gmail.com> wrote:
Well, it's been a while, but I have made steady progress on the 17.5" f.4.5. I uploaded some new shots to pages 5 and 6 of my Gallery:
http://www.utahastronomy.com/Chuck?page=1
The clamp-ring mold worked well. Although 4 parts are visible in the photo, I molded 5 so I'd have a spare if one turned-out poorly, but they all seem to be perfect copies of the master pattern. Next week I will finish the machining and bodywork and mount up both pairs on the main tube for final fit checks and adjustments, if required. They will be felt-lined on the completed telescope, and will allow tube rotation as well as longitudinal balance.
I can then make my final decision on the length of the bridge plates (the side plates that join the front and rear clamp ring assemblies). A PVC radius block spacer will provide the interface between the curved rings and the flat plates, in 4 locations.
The fiberglass tube turned-out well. There was a bit of pre-release around the fan pocket and access door, necessitating some minor bodywork, also the rough interior of the Sonotube was of course transfered to the tube, but this was expected and dealing with it is straightforward. Only elbow grease and a long sanding block are needed to eliminate all the minor tube imperfections prior to painting. I like the looks of a traditional white tube, with black trim. Any structural metal parts (aluminum) will be given a high polish, hardware will be stainless steel for corrosion resistance.
I still need to make master patterns for the end ring and back cover plate. These will give the tube a professional, finished appearance, streamlining the tube as well as adding stiffness near the spider. The entire tube will be closed when not in use, keeping dust away from the optics. The primary and secondary mirrors will also have their own close-fitting covers. The primary cover is removable through the lower access door.
So-far, so-good. Stay tuned. _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
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