"mc" wrote in message
. ..
"Karl Uppiano" wrote in message
news:XTrtf.800$yW1.129@trnddc05...

Off topic, and a bit of a quibble, but it isn't centrifugal force that
causes inward skating. If you draw a line straight back from the tonearm
shell, you will find that it misses the tonearm pivot by a distance
(offset) of about four inches. The force of friction of the stylus
dragging on the record times the offset creates a torque around the
tonearm pivot that makes the whole thing tend to skate inward.

Thanks - that's the clearest explanation of skating I've ever heard. The
essence of it is simply that the record is pulling on the cartridge, but
not pulling it directly away from the tonearm pivot, hence the tonearm
wants to pivot in the direction in which it's being pulled. Right?

By the way, my explanation is a first approximation. The head shell angle is
a compromise. It is only parallel to the grooves at one point in its arc.
What you really want to do is draw a line tangent to the groove at the point
where the stylus contacts the record at any given moment.

The force of friction of the stylus also varies as it moves to the center of
the record, as well as with the amount of groove modulation, vinyl
composition, stylus shape and tracking force (the only things designers ever
really even attempt to take into account) and so on.