more Rake Angle stuff

[James Ellis]

Gentlemen:

I have been reading the latest posts on this subject, and I see that some
confusion still exists.  I won't single out any individuals, but I will try
just once more to resolve the confusion.  It's really easy understand, once
you see it.

In a real piano, be it grand or vertical, in today's world, there is no way
to make the crown of the hammer hit the string in a perfectly perpendicular
direction.  You just can't do it.  You can make the hammer perpendicular to
the string easily enough.  We do that all the time.  But the only way to
make anything hit the string perpendicularly is to put the center of the
arc from which it swings in the same plane as the string, and there is no
way to do that in a real piano the way they are made today.  Go back to
that drawing that I suggested you do, and construct it for yourselves.
Better still, just go to any vertical piano.  Slowly move the hammer with
your finger.  Watch the direction of the crown as it touches the string,
and you will see that it is not moving perpendicularly to the string,
despite the fact that the axis of the hammer may well be.  The crown will
have a slight downward component to its motion.  That's because the center
of rotation is away from the plane of the string.  That's just the way it
is, and there is nothing we can do about it.  All we can do is minimize
that grazing effect by putting the center of rotation as close to the
string as possible.

Sincerely, Jim Ellis