Rake Angle, and More

[James Ellis]

I see that my comments about "rake angle" have stirred up other comments
and arguments.  All I was trying to do was to show you fellows that just
because the hammer is pointed straight toward the string, it does not mean
that it is moving in that direction.

Someone sent a jpeg image to illustrate a point.  My computer has jpeg as
well as psp, but that illustration came through as two pages of jibberish.
The system either can't handle it, or else I don't have the right version
of jpeg to read it.  It doesn't matter.  I understood what he was talking
about.

I was trying to expose a fallacy, and I think it worked.  I was not
advocating some crazy impractical design.  Theory and practicality often
don't go hand in hand.

A few years ago, many piano technicians believed that a tuning hammer with
a very short head would reduce the bending force on the tuning pin despite
the fact that the head was bored at a very high angle, which elevated the
handle and put the tuner's hand high up in the air.  (I'm using a grand
piano for illustration.)  I saw that I was getting nowhere when I told them
that the very high angle of the handle defeated the effect of the very
short head, because it put the application of force high up above the
tuning pin.  So finally I said, "OK, keep raising the angle of the handle
until you have it pointing straight up.  Now, what will that do"?  PAUSE -
PAUSE.  "OH, yeah, now I see it"!  Well, I was not advocating a tuning
hammer with the handle pointing straight up.  I was using an absurd
illustration to make a point, and it worked.

As long as we have actions where hammers are attached to shanks that swing
in arcs, we will have hammers that do not move straight toward the strings.
 No matter what we do, that hammer is going to be rotating about an axis as
it moves toward the string, and the crown will hit the string a somewhat
glancing blow.  All we are trying to do is to minimize that glancing blow.
Actions have been visualized in people's minds that enable the hammers to
hit the strings straight on, but they are very impractical, so we don't go
there.  We just stay with what is practical, and try to minimize the
shortcomings.

Sincerely, Jim Ellis, RPT