Telescope Reviews: The Blue Moon observatory

I gleaned much information about pier design, shed design etc. here, but I was unable to find as much about plate design for a CG-5 GEM. And even less on how to secure the mount to the plate.

Here is what I did. I started with two 8” x 8” x 1/2” aluminum plates from McMaster Carr. I used four 1/2” holes for the threaded stock going into the concrete, and four more for the 8” long threaded stock tying the upper and lower plates together. This much I learned from you guys. Here is how I clamped my CG-5 to the top plate. I went to my local home center and bought a 2 3/8” metal cutting hole saw. The tapered sleeve at the bottom of the mount that sets in the tripod head is almost exactly 2 3/8” at it’s widest.

I cut the hole in the top plate, and saved the plug that I cut out. That hole is a tighter fit than the hole in the top of the tripod’s head. And the GEM sat down onto the plate nicely. Another smaller hole tapped for a bolt of it’s own makes mounting the right ascension post on the upper plate a piece of cake.

With my upper plate all but finished, I turned my attention to mounting my mount to the plate. Taking that plug of aluminum I cut out of the upper plate, I started to fashion a hand knob to cinch down my rig.
I picked up a 2.5” long 10 mm bolt with a 1.5 thread count as it is what is needed to thread into the bottom of the mount. I drilled the plug to accept the 10 mm bolt as a press fit. After pressing (read hammering) them together, I chucked the bolt/plug combo into a hand drill and clamped the drill in a bench vice as a poor man’s metal lathe, I then shaped with a flat file and polished with steel wool the aluminum plug until I had fashioned it into a fine hand knob. I slipped a bronze sleeve over the bolt just to act as a spacer, until it seated onto the hand knob, and then set a large flat steel washer on top of that.

I then cut another 2 3/8” hole in a piece of 1/2” plywood, then cut the hole out to make a 3 1/2” outside diameter, 2 3/8” inside diameter donut. I cut another 3 1/2” circular piece and glued them together. And I slipped the bolt/hand knob through the center of this wooden spanner to finish my tie-down. The hole in the upper piece of plywood slips past the mounts sleeve as it is coming down and passing through the aluminum plate. The lower piece of plywood stops the bolt as it is passing up into the mount. It is an very elegant and effective solution to how to securely tie the CG-5 GEM to the plate.

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11” Celestron XLT SCT
Orion ED80 APO
CG-5 GEM
JMI NGF-CM Focuser
Orion SSDSI
Meade DSI Pro
an assortment of 1.25” & 2" stuff
all tucked inside the Blue Moon Observatory
http://tinyurl.com/29b9wn
Basically more scope than my abilities warrant

"I know I can never look upon the stars without wondering why the whole world does not become astronomers."
Thomas Wright