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2/17/2007 - Secondary Cage Design Process

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After heading off to play with my new snow shoes in the newly fallen snow in Greenfield and North Adams today I decided to sit down and do the actual design and template generation of the Secondary Cage. This process included creating CAD drawings of the cage rings to use as full size templates to locate aluminum struts, focuser board and mounting holes for the upper pole clamps. These templates will be printed on a plotter and used to mark the various component locations on the rings. You'll find some pictures of the preliminary CAD drawings below plus what the desk of a person designing a secondary cage looks like! NEXT UP: The Secondary Cage comes together!

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Protractors and Scales and tables and AutoCAD oh my! This simple CAD drawing was used to properly place the center of the secondary mirror, and therefore focuser in the cage such that the focuser is 8 inches from the top of the cage. This distance will provide ample light baffle for most dark-ER skies. Should I need more baffling, a simple and LIGHTWEIGHT Kydex baffle can be attached to the top of the cage with Velcro dots opposite the focuser. Using the installation instructions of the Protostar spider and holder, I then properly located the mounting holes on the strut for the spider (left). Here is what will be printed as a full size template on a plotter to mark the locations for the curved focuser board (more on how I'll make that later), strut seats and upper pole clamp mounting holes. Focuser: JMI Next Generation Dual Speed Crayford 2 inch Focuser.

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