hammer velocity

[Farrell]

This is a multi-part message in MIME format.

---------------------- multipart/alternative attachment
I may not know much about pianos, but I know a little about physics! =
Comments below:

Terry Farrell
 =20
----- Original Message -----=20
From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
To: "Pianotech" <pianotech@ptg.org>
Sent: Saturday, April 26, 2003 2:59 AM
Subject: Re: hammer velocity
=20
> Richard Moody wrote:
>=20
> > YES!  The hammer as it strikes the string is actually slowing
> > down in theory.    A major consideration of the design of the
> > piano action is that the hammer must leave the  impelling device,
> > (jack) and continue to travel for a tiny distance free and clear,
> >  strike the string, rebound, and then come back in contact with
> > the action mechanism which must now "catch" the hammer.
>=20
> I believe there is a letoff position (just under 1mm) that is so close
> that the hammer does not have a chance to start de-acceleration. I
> havent gotten into all this side of things very much yet, so I am not
> sure of myself here, but isnt there some sort of "left over" force =
that
> keeps an object in acceleration for some small period of time even tho
> the origional applied force is removed ?  Like a bullet coming out of =
a
> rifle ?? Doesnt that meet its maximum acceleration some few =
milliseconds
> after the explosion of the shell ?

There won't be any "left over" force directly related to the downward =
push of the keystick driving the hammer forward after letoff. Relative =
to that, the hammer would indeed start decelerating (and hence slowing) =
because of friction. As soon as the driving force is removed, =
acceleration stops. A separate force is required for any other =
acceleration (like friction accelerating the hammer in the opposite =
direction, or decelerating if you prefer). Now like you point out, there =
may be some other additional force acting upon the hammer in that last 1 =
mm of travel like the hammer shank springing back. Although, in an =
upright, because of the mass and hence inertia of the hammer compared to =
the hammer butt, I would think most of the effect of any =
straightening-out the hammer shank does would more greatly decelerate =
the butt. But of course, not so on a grand.

Don't know about bullets and rifles. Too dangerous.

> >     The only aspect of the travel of the hammer the pianist can
> > control is its velocity.  There might be an argument about this in
> > physics because of the difference between velocity and
> > acceleration.
>=20
> I am sure you are right here.... (about the argument part) I have read
> through 8 or 9 articles by those who have done the only readily
> available real science on the subject matter and they dont draw any =
hard
> conclusions. Most say that things seem to point in the direction you
> mention, but the door seems held open and there are others who have
> their foot through that door. The physchology of our perceptions gets
> into play here as well, along with what is heard and coincidently =
felt.
> Physics experiements have a hard time avoiding isolating too much in
> order to afford an appropriate resolution for what they are trying to
> look at, and in effect influence that which they are viewing. We must
> never discount the reported experiences of the pianists in all this
> either. The idea is to find the explaination as to why they experience
> what they do.
>=20
> --
> Richard Brekne
> RPT, N.P.T.F.
> UiB, Bergen, Norway
> mailto:rbrekne@broadpark.no
> http://home.broadpark.no/~rbrekne/ricmain.html
>=20
>=20
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives
---------------------- multipart/alternative attachment
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/56/88/40/12/attachment.htm

---------------------- multipart/alternative attachment--