Re: ATM Alternatives to Nylon-tipped screws

["clement.focuser" <clement.focuser@verizon.net>]

Hello Chuck,

> 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.

The problem of Nylon screws loosening is news to me. I have found that Nylon
screws do not loosen. The threads deform and hold the screws in the same way
as the Nylon locknut works. Could the effect of loosening  have been due to
some other cause? Aluminum screws, unless hard anodized, will gall.

A method of making for making plastic tipped metal adjustment screws that I
have used is to start with a SS allen head socket screw. At the end of the
screw I turn a nipple with an undercut (ideally a spherical nipple). I then
cut a cylinder less than the screw diameter of  plastic, such as Delrin. A
blind hole is drilled in the end of the plastic cylinder slightly less than
the nipple diameter. The plastic cylinder is pressed onto the nipple. A
press-on thumb screw head is pressed onto the socket head  to complete the
adjustment screw. The advantage of this arrangement is that the plastic tip
can rotate and swivel as the screw is adjusted. Sometimes I will use
anaerobic blue or purple Loctite to the screw threads for that Nylon screw
thread feel.

Don Clement
Running Springs, California
Rim of the World