2015-12-10: SOL FINDER

So is this how people find their sol-mate??

Just about every picture you see of a small Lunt telescope shows a Tele Vue Sol-Searcher mounted on the scope. Clever name. It is, of course, a viewfinder for locating the Sun when initially getting the telescope set up -- which is not quite as easy as you would expect. It works like a pin-hole camera with the light from the Sun coming through the hole on the front and projecting a small disk of light on the white spot in the back when the telescope is aligned. I didn't want the other telescopes to make fun of mine, so when I ordered the scope I ordered one of these too. During first light it was pretty much dead-on accurate. I didn't have to adjust anything. The only problem I had with it were the two silver things laying in front of it.

One of the first reviews I read about the Lunt 60mm after it started being sold complained about there not being enough room in the carrying case to leave a Sol-Searcher attached without having to cut a hole in the lid foam. I didn't want to do that. How tacky.

At the top of the clamp ring that goes around the telescope's tube there is a groove and two bolt holes that look like they were made for the Sol-Searcher. Actually, it's probably the other way around. The holes are 3/4" apart, are about 1/4" deep, and are threaded for #10-32 bolts. Just for future reference the groove is just under 5/8", or is close, if not exactly, 16mm in width.

I went through several iterations of how to do this modified mount, and finally decided to use two non-stainless steel set screws. Why not stainless? Because stainless steel isn't very magnetic. Get it??

I've used a lot of magnets in woodworking projects the last year. You can get just about anything you want in terms of little magnets from K&J Magnetics in New Jersey. It took a couple of orders, but these 2/10" diameter, 3/8" long Neodynium Rare Earth magnet cylinders ended up being just right.

   

To start I put a dab of medium Loctite on the set screws and ran them into the holes in the ring. The holes are 1/4" deep and the set screws are 1/4" long, so I screwed them in all the way, then back out 1-1/2 turns. This makes them stick up into the holes on the Sol-Searcher a bit and provides a little mechanical support to keep the finder from sliding back and forth. The next size up in set screws that I could find were 3/8" in length, which would have left about 1/8" sticking out. That seemed like a bit much, and I didn't want to leave the screws all of the way in to where they touched the telescope tube, so backing them out 1-1/2 turns would have made them stick out even more. If I left them screwed all of the way in THEY WOULD HAVE SCRATCHED THE PAINT, OK?? (I'm still at that stage of ownership.)

Next I applied a bead of the 'no run gel' version of Krazy Glue to the area of the two magnets as indicated in this NASA simulation picture. I couldn't take a picture of this step, because I was too busy trying to not glue myself to the magnet. After the glue was on I pushed the end nearest the glue down from the top into the bolt holes in the Sol-Searcher. I was trying to get a nice layer of glue between the magnet and the sides of the holes without getting any near the heads of the set screws. It seemed to work OK. I put the finder on the scope and finished pushing the magnets down until they touched the set screws.

The sizing of everything left just a fraction of an inch of the top of the magnets sticking out of the tops of the bolt holes, but still down in the counter-sink holes. I put a good drop of the runny kind of Krazy Glue into each hole to further help keep the magnets in place...which makes more sense than putting glue in there to grow flowers.

The set screws poking up cause this end of the magnets to be recessed a little, and the length of the magnets keep them down below the tops of the counter-sink holes, so there won't be much of a chance that they will become stuck to many random things. If you take these two magnets and hold them an inch or two apart and let them snap together I'd say 80% of the time one or both of them will fracture. They are magnetically strong, but very brittle. I didn't want any part of the magnets sticking out into thin air so they could smack onto anything and break. You can see in the first picture of the magnets that I ordered three of them. I learned that lesson a couple times.

And thar she blows. When you pack up the scope you just have to pull the finder off. It's always a bit of a crap shoot to get the pull right, but the 3/8" long version of these magnets appear to have the right amount of power to keep the finder stuck to the scope even in a slight gale. If I get caught in a storm at least I won't have that to worry about.

THE END

2018-03-03