Some ten or twelve years ago I began to think about the problems of noisy action on the bassoon, and realized that the greatest cause of noise was occasioned by two unrelated aspects of the pivot-screw/arbor relationship. The first aspect is that, of course, any bearing surface will eventually wear, but the bearing surface of the pivot screw/arbor has a much harder surface on the pivot screw, which is made of steel than the arbor which is usually German silver. Thus the wear takes place on the arbor, rather than the screw. If the screw were softer, the wear would take place on the screw which could be easily replaced when wear occurred; a much easier repair than the one which is necessitated when the arbor is worn. The second aspect is that once wear has occurred, the two parts which vibrate against each other are metal, thus causing a relatively high noise potential.
Delrin is a plastic material similar to Teflon, which seemed promising for screw manufacture for several reasons. It has the quality of not needing lubrication against metal, thus avoiding the need for oiling, also since it does not need lubrication, there should be less wear. When wear does occur, it should occur on the screw which can be easily replaced, and additionally, the metal arbor vibrating against the Delrin, even when wear has occurred, is much less noisy than against steel.
Thus I had a machinist make me, by hand, one by one, a set of screws for my bassoon. I installed them, and began using them, meanwhile keeping a set of Heckel screws in my case (they are still there, perhaps one never becomes 100% trusting). I played several tours with no problems and decided to try to get some made up in a more professional manner, both so as to be able to have more of them and so that they would be more consistent. I had a prototype made, which worked perfectly on my instrument, but when I tried it on a student's brand new instrument, the screw would bind. This was, no doubt, because the arbors on the new bassoon had had no wear, and thus the apertures were smaller. So I had the pivots made somewhat smaller. The result was that they worked perfectly in the new bassoon, but were somewhat loose in mine, and in fact in any bassoon which has had some wear. In any event, I had a number made up, and several bassoonists in the U.S. and abroad began asking for screws. I am indebted to Bernie Garfield for a wonderful solution to the problem of using the screws on bassoons which have had some wear, or in any case where the pivot seems loose. Obtain some .001" brass shim stock. Cut a piece 1/4'' by 3/16th''. Roll this into a small tube and place it in the arbor. This provides a new bearing surface for the Delrin screw (a very quiet one by the way) and takes up the slack, thus reducing the noise.