pin comparisons

[larudee@pacbell.net]

Ed,

It's not just the difference in the amount of string moved per degree of
rotation.  It's also the the amount of flex in the pin, the torque exerted by
the string tension, and the increased block friction required to overcome that
torque.  All of these factors combine to make a difference.

That's part of the problem with having the article split between two Journal
issues.

Paul

A440A@AOL.COM wrote:

> Greetings,
>    I have just finished Paul's article this month in the journal.
> Interesting views can be found on all aspects of tuning pins, since we all
> spend so much time with them,  and I am wondering what the numbers can tell
> me. Specifically, the difference in tuning control between sizes of pins.  I
> don't think that the increased radius of the larger pin is a significant
> factor.   I find (admittedly, I am NO math whiz, so if I have missed a step,
> please disregard everything that follows), that by determining the
> circumferance of two different sizes of pins, and then relating that to
> degrees of movement, the differences begin to seem academic.
>     Here is how it looks to me:
>
>    A pin that is .272" in diameter has a cir. of .85408".  This equates to
> .00237" per degree of rotation.  A .286" pin, by the same calculation has
> .0025" per degree of rotation. This means that the larger pin will move the
> string approx.  .0001" more per degree of rotation.  If we consistantly move
> pins by increments of 6 degrees in fine tuning, then the difference in pin
> size accounts for maybe .0006" (that is 6 ten-thousandths!!) difference in
> string length being pulled around the pin.   ( I have omitted the 1/2 string
> diameter from the circumferance equations,since that is a variable on a per
> string basis, though increasing the diameters of the two calculations would
> further reduce the percentage difference between them).
>    Since difference as it relates to tuning is based on changing the tension
> per degree of rotation, and tension/pitch relationships are functions of the
> square,  I have to ask just how much difference can be found from  .0006" of
> string movement, at the pin?  I don't think it would be a discernable
> quantity. Others?
> Regards,
> Ed Foote RPT