more Rake Angle stuff

[Keith Roberts]

James, I understand this. I'm sorry my jpeg didn't come through. It was a
drawing of the arcs created by a hammer, with one flange closer to the
string plane. I use the center of mass of the hammer instead of the tip of
the hammer because that is what controls the direction of force in the
hammer.
Well written post. Thanks
Keith Roberts
----- Original Message -----
From: "James Ellis" <claviers@onemain.com>
To: <pianotech@ptg.org>
Sent: Friday, March 14, 2003 2:49 PM
Subject: more Rake Angle stuff


> 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
>
>
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives
>
>