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Stubborn screws.

That tip about using Chap Stick as a lubricant was terrific (S&T: December 2011, page 66). It reminded me of a trick that I learned four years ago, suggested by my late brother-in-law, Pat Nocera, who was a materials expert.

I mount my 60-mm Celestron zoom spotting scope on a wooden tripod topped with a cast-iron alt-az fork mount. The mount uses two thumb screws to lock the scope in place, but the azimuth screw was always either totally loose or totally tight. Since I often use this scope at the Jersey shore to follow ships on the horizon, I wanted the scope to remain stable in a stiff, ocean breeze yet still be able to pan left and right without my needing to constantly loosen and tighten the screw.

I planned to put a pencil eraser into the screw hole, which I knew should work, but Pat pointed out that it would soon shred and gum up the works. He suggested I try a piece of solid polyethylene, like the "cork" found in some wine bottles. This material has a rubbery consistency but never shreds (in fact, I had a devil of a time just cutting off a small piece with a very sharp knife). I eventually fashioned a small, cylindrical plug, inserted it into the thumbscrew hole, put the screw back in, and tightened it down snugly until the friction felt right.

Four years later it still works flawlessly, with no sign of any wear on the plug. I never need to touch the azimuth screw now. The scope is always stable, yet turns smoothly with just moderate hand pressure. If I want a stiffer feel, I just tighten the screw some more. The hand pressure required goes up, but the smoothness never varies. The same solution worked with the altitude screw, too, although the plug falls out if I remove the scope from the mount. I remember Pat fondly every time I use this scope.

Tom Sales Somerset, New Jersey

For the Record

* In the table that begins on page 70 of the September 2012 issue, the double star Struve 2303 was erroneously listed in Scutum. It is located just across the border in Serpens. A few lines below that, Struve 1181 should say 1881.

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Title Annotation:Letters
Author:Sales, Tom
Publication:Sky & Telescope
Article Type:Letter to the editor
Date:Nov 1, 2012
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