For veteran Southern Skies Star Party participants, the issue of reaching the 16 degree declination is a problem for most fork-mount and schmidt-cass telescopes on the market. This year, in preparation for his trip, one resourcefull participant opted to build his own sollution in a garage-made wedge and mount.
On the Wedge for the NexStar:
There's a place by me that sells what I call "bar stock" which would be flat, angle, and either round or rectangular tubular pieces of metal in 20 foot lengths. Well they also sell used (leftover) barstock, and they will cut things for customers. So they end up with odds and ends. Well I found a piece of aluminum I beam with about a 2" by 4" dimension, and rather sturdy thickness. There's probably no reason the same thing couldn't have been done with a piece of box tubing, but there might be some bolt accessibility issues.
Well, since the shorter dimension is only 2" I was able to simply cut it at an angle with my $140 Sears 10" table saw. Aluminum cuts very well with a table saw, but unlike cutting wood, it spits high speed but light weight metal bits at you and you definitely need safety glasses, and you'll probably shield the rest of your face with your free hand. It will also need to be touched up with a file so that the sharp edges don't remove meat from my hands and any other body parts that touch the wedge.
I simply did my best to get a 16 degree angle (by adjusting the angle between the blade and the table), knowing that I might have to either shim between my tripod and the ground or simply put the correction between the tripod and the bubble level ($1.50 at Sears).
Okay I actually started out with two separate pieces about 14" long that had perpendicular cuts. So by cutting a ~16 degree angle on one end of the first piece, its rails rest along the rails of the other piece at a 16 degree angle from perpendicular. Before I even started I drew a diagram with a circle for the world, a tangent line at 16 degrees south of the equator, and a line through the north and south pole. This helped me visualize the angle that I needed to achieve (106 degrees).
Now since we don't know each other very well, it might be useful to agree on the verb form of the word "sister." To "sister something up" usually means to place two boards next to each other and fasten them together securely, straight and adjacent. Like two sisters that are always together and inseparable, walking side by side.
I sistered each side of the angled I beam with a piece of 1" square box tubing (4" long) that extended to the horizontal I beam that it rides on, and simply bolted through the box tubing and into the rails of each I beam. But before I did that, I bolted two peices of the 1" box tubing to the outside edges of the horizontal I beam at the end, perpendicular and reaching up to the extended end of the angled I beam.
I used washers and lock nuts on all bolt joints and I didn't crank on them too hard because this is Aluminum. It feels rock solid, but I hope that it is of appropriate scale for the NexStar.
The tripod was different. I bought a circle of nice wood (looks like the top of a wooden stool). That will be the horizontal platform of the tripod. I bought about 9 feet of 1.5 outside diameter aluminum tubing (round and about 1/8" thick) and cut it in three equal pieces (here's the first time I measured the length of anything). Again, I cut it with the Craftsman table saw. Then I went and bought a wooden dowel of 1.25" diameter, hoping it would fit right snug inside the aluminum tubing. It's just a little too thick so I had to sand the pieces down a bit. I bought a 1.5" holesaw (for the drill) that can cut deep holes. I dreamed up an angle that I wanted, and cut two pieces of wood with that angle (I just eyed it up, no compasses). These two pieces I fastened to a piece of 2x6" pine, placed it under the drill press, and drilled three similar angled 1.5" holes through the pine. Then I cut the 2x6 pine into three separate pieces, each with a similar angle hole. Then I glued the dowels into the holes (about 6 to 8" of dowel total).
These three pieces of wood can now be easily fastened to the circle, and will have legs protruding at reasonable looking tripod leg angles. After sanding the dowels, I can stick the three aluminum tubes onto the dowels. For the feet, I cut pieces of dowel at the same angle (using the pieces of the fixture I made earlier) and I can fasten hockey pucks to them to make nice soft feet that hide the sharp edges. It disassembles but is not adjustable.
I thought all of this through, but none of this is a proven design yet. But it is cheap, strong, lightweight and transportable. The wedge could probably be enhanced with another accessory to make it 45 degrees for Minneapolis, or maybe I can just leave the wedge down there where it is 16 degrees. Right now I don't know of anywhere else I might go that's 16 degrees, except maybe Oaxaca, Chiapas...
Jim Russell, Minneapolis MN
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