Saturday, July 17, 2010

Case for upper cage

Now that the upper cage is complete with the exception of installing the secondary mirror, I had to build a case for it to keep dust and inquisitive little kitties from getting into it. Nose prints and cat hair all over the secondary mirror won't lead to the best views I could get from a premium quality set of optics, so I bought a sheet of high quality softwood core, hard wood veneer plywood. After taking careful measurements of the cage, I made a box with inside dimensions of fourteen and a half inches deep and twenty three and a half inches on a side. After all six sides were glued up, I carefully split the box into two parts on the table saw, then made a support to rest the cage on. I cut an radius to accommodate the inner shell of the upper cage, and drilled two holes in the cross pieces for the struts. Alas, the assembly turned out a little too big, so I split it into two and glued two more cross pieces, then glued them together before gluing them to the bottom of the case. I then uses a trim bit to knock off beads of glue followed by a 3/8-inch round over bit on all outside edges. I plan to finish the case with three or four coats of exterior grade, glossy polyurethane. In the bottom will be foam padding in which the Telrad and computer for the digital setting circles will be stored. I will make a lip of 12-gauge steel flat bar to keep the lid in place, and skids will keep the cage from bumping the sides of the case. I'll be using padding on the bottom support, lid and skids to keep the upper cage in good condition for many years to come.