Re: ATM Alternatives to Nylon-tipped screws

[George Anderson <georgea@cam.org>]

If you have enough space on the end of the bolt (finder bracket screws)
why not install a nylon acorn nut? It should give you the paint
protection and a drop of loctite will ensure that it stays on the bolt.

George Anderson
Montreal Canada

Clear skies and good health

Chuck Hards wrote:
> 
> I recently made some finder-bracket alignment screws by using aluminum
> screen-door thumbscrews (these come in 6-32 & 8-32, with a knurled top for
> gripping) and gluing-on a "pad" of flocked paper.  The end of the screw was
> flatted first in my mini-lathe, but you can do it by hand with a sanding
> block.  The flocked paper "fuzz" flattens out fast, but stays on the end of
> the screw and provides paint protection if you don't tighten it enough to
> drive it into the finder barrel.  The screws must be mounted in the ring
> straight.  If the hole was tapped off-center or misaligned, the edge of the
> screw can gouge the paint, especially on longer tubes.  A little chamfer on
> the screw tip allows for a teeny bit of misalignment.
> 
> Using an aluminum or metal adjustment screw eliminates the major problem of
> Nylon screws:  They constantly loose tension, and must be re-tightened.
> Sometimes several times during the same observing session.  Owners of Meade
> finder brackets know what I mean.
> 
> On the 3" finder for our club's 16" Cassegrain, I used standard round-head
> 1/4-20 bolts for the adjusting screws.  I flatted the head in the lathe, and
> lined it with flocked paper.  They were threaded into the rings backwards,
> and a plastic hand-knob superglued on the threaded end, now on the outside
> of the ring.  The flatted head of the screw is so large (about 3/8") that
> the finder tube curves away from it and it only contacts it on a line down
> the center, running fore-and-aft.
> 
> Chuck