2017-07-27: Tab A To Slot B

Does anyone put things together with tabs and slots anymore? I guess astronomers do. Kinda.

I bought a Celestron Evolution 6 telescope and mount so I could experience the nirvana of a "GO-TO" telescope mount, or at least see if my karma was able to handle the nirvana. The Evolution (Evo) mounts have saddles that are able to grab a Vixen-sized dovetail. These are about 1-1/2" wide. The basic Evo mount is the same for all of the sizes of telescopes in the series (6", 8" and 9.25"). I thought it would be nice to be able to put some of my other telescopes on this mount. They all have Vixen bars...except one.

My Celestron EdgeHD 800 has a Losmandy/CGE dovetail on it that is almost 3" wide. So an adapter had to be made.

That was fast. Good ol' B&H in New York had the Losmandy GM-8 saddle and 4" dovetail that I needed in stock(!), both at the same time(!), and when I needed them(!). That never happens. I ordered them and got them in just a few days.


I scrounged up some nuts and bolts and got it together. The center 1/4"-20 bolt was screwed into the threaded hole on the dovetail. That kept things from sliding around, because the other two bolts were not in threaded holes. It turns out that 1/4"-20 jam nuts will fit into the recessed area of the slots on this dovetail. No tools were needed to keep the nut from spinning while tightening the bolt. The two holes in the saddle were made for for 5/16" bolts, so I found some thin nylon washers made for 1/4" bolts that fit well in the recessed area. That kept the heads fairly well centered while the bolts were tightened.

Even the colors kinda matched. You can see that the shaft of the locking screw on the Losmandy saddle was pretty close to the piece of decorative plastic on the mount. That piece of plastic is the shape of the telescope that was purchased with the mount. A 6" scope in this case. It fools lesser minds, like marketing people, into thinking that the scope tube is at one with mount arm. In this case it just got in the way. The silver spacer needed to be added to get the saddle a little farther out from the arm saddle. Where did that spacer come from??

You may remember that chunk of aluminum as the first piece of astro equipment that I had made way back in 2015 for my first (new) telescope, the Lunt 60mm solar scope. It was made for kinda the same purpose. I measured that the holes would line up (the two with the nuts and bolts are 35mm apart), so I dug it out of storage and used it. Perfect.

Here we go! Hey, it didn't fall off!

What a piece of engineering. I wish I could make parts like that from scratch. If the weather ever clears up I may get to feed the mosquitos and try using it.


UPDATE 2018-05: I needed to take the curved plastic piece off of a Celestron SE mount for a heliostat project I was working on. When you do that on an SE mount a big portion of the elevation gearing is exposed. I had to fashion a flat piece of plastic to cover it all up. This doesn't happen on an Evolution mount, so I just took the plastic off. This made it possible to remove the extra silver spacer from the adapter. Now it works greater!