The Stylus


That's what it is, a phonograph stylus, as 'seen' by a scanning electron microscope. ...The first impression I got from the one on the top left was that of a Polaris missile breaking the surface of the water.....It may seem hard to believe that the tip measures .0002" by .0007". ....What's even harder to accept is the fact that it's wear is due to friction against the walls of the record groove. . Imagine, as soft as is the vinyl of a record yet it can wear the hardest natural substance known - diamond.



The black area is the worn part and the white goop is dirt. The stylus was purposly not cleaned before taking the photos. It's no wonder one can hear pops or clicks while playing a record. If the black area was an automobile, that white lump would be one heck of a big boulder on the highway.

A quick calculation to bring the above sizes in relative proportion and speed to that of an automobile. At 33 1/3 rpm, the surface of the record moves past the stylus tip at roughly one mph at the beginning of the record. Not fast. However, the narrow width of the stylus is 0.0002 inch. So, at 1 mph, (17.6 in./sec.), the lump passes the stylus in 0.0000114 sec. (1/88000th of a sec.), a distance approximately equal to its width. So, if an automobile had to cover a distance equal to its width, ~6 ft, in 1/88000th sec., it would have to be travelling at 100 miles per second, or 360,000 mph., aomewhat beyond the speed limit on any highway.

I realize this sounds ludicrous but I have read reports that claim that the temperature at the tip of the stylus can exceed several hundred degrees Centigrade. Crystallized carbon, (diamond) burns at 900 deg. C. Considering the small size of the tip and it's short duration at any point on the record, the heat is dissipated as fast as it's generated; well, almost. The record absorbs a lot, probably most, and the diamond, the rest. Perhaps it doesn't actually wear due to friction as much as it burns. Heck, it's only carbon 12.



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