Thursday, September 8, 2016

DIY Astroscan Telescope Chair Mount

The Astroscan ball scope is my choice of high power binoculars replacement for relaxed observations of wide field objects. To boost the comfort even more, I've made a very simple but extremely efficient and very compact camping chair mount for its base. 

A small pouch and a single pole pictured above are all I need to pack. Both are riding right in the chair's sack.

Inside the pouch, I'm keeping the mount (aluminum thing on the left) and the electric screwdriver, which is a great thing to have for many other occasions as well.

The mount is basically a two-way clamp, which I've made out of four identical aluminum square bars, which I had laying around from an older furniture project. The pole is a steel tube scavenged from an old badly torn apart camping chair I've found near a vacant campground. I ground each bar with Dremel sanding drums to produce rounded clamp cheeks matching chair's round poles radius (chair's back pole and the additional one), and then drilled 4 times and tapped 2 times each (my favorite 1/4"x20 machine screw thread) as necessary to tighten both two-sided clamps. Note that the screws in the middle are mounted as far as possible from the ends. That makes clamp assembling easier, as that way rods can slightly rock around that axis, relaxing the clamp more readily.  

Mount is installed, view from the front.

View from the side.

Closeup One. You can adjust X and Z moving the clamp along the back pole, and moving the additional pole in the horizontal clamp cheeks. And surely rotate both as needed to position the eyepiece comfortably at any position to accomodate a target in the sky or the chair's position (especially crucial when in reclined mode). 

Closeup Two. You can adjust Y axis rotating the clamp around the chair's back pole. I don't clamp it hard, which allows to rotate it more or less freely when relieving the applied weight (hand supporting the Astroscan for a moment), which also allows to get in and out of the chair easier. When let go, the bending force from the scope weight keeping it from sliding down.

The Astroscan ball mount is a simple 1/4x20 allen head center screw (that demo image is incorrect, as the nut actually goes on the other side of the pole; still, it holds very well as is anyway, because of the intentional slant in the base).

After tightening the central screw, I'm moving one of the Astroscan base's legs over the pole, which introduces a springy slant at the screw joint, making a beneficial tension in the construction which holds the base in the convenient position by two contact points much more reliably than only by one. 

Closeup Three.

I can mount that clamp on any typical folding camping chair or a cot.

  1. It's better to add a beveled edge to the clamps cheeks to prevent cutting the poles' sides.
  2. It's counterproductive adding screw handles (yes, I've tried that), as they will interfere with each other, with the chair, and making the clamp piece cumbersome to pack. Also, the electric screwdriver will help to assemble/disassemble it much faster, and it is always with me in the field anyway. 

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