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<DIV><SPAN class=256013919-30112001><FONT face=Arial color=#0000ff =
size=2>comments interspread below for discussion =
purposes:</FONT></SPAN></DIV>
<DIV><SPAN class=256013919-30112001><FONT face=Arial color=#0000ff =
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=256013919-30112001><FONT face=Arial color=#0000ff =
size=2>Marcel</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT =
face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> =
owner-pianotech@ptg.org
[mailto:owner-pianotech@ptg.org]<B>On Behalf Of </B>Jon =
Rhee<BR><B>Sent:</B>
30 novembre, 2001 12:37<BR><B>To:</B> =
pianotech@ptg.org<BR><B>Subject:</B> Re:
flagpoling or killing pin-block?<BR><BR></FONT></DIV>
<BLOCKQUOTE>
<DIV>My interpretation of the whole issue of bending of the =
pin is
this: The tuning the pin flexes upwards while one raises the =
pitch
whether one realizes it or not. <SPAN =
class=256013919-30112001><FONT
face=Arial color=#0000ff size=2> </FONT></SPAN></DIV>
<DIV><SPAN class=256013919-30112001><FONT face=Arial =
color=#0000ff
size=2>"Only if you use the lever between 9 and 11
O'clock"</FONT></SPAN></DIV>
<DIV><SPAN class=256013919-30112001> </SPAN> This =
is due to
the many forces acting on the pin during the raising of the =
pitch.
At rest there is the string tension pulling downwards on =
the
pin, not only a rotational tension but a vertical tension. The =
rotational force (torque) is balanced by the static friction between =
the pin
block and the pin. The downward force is balanced by the =
strength of
the elasticity of the steel in the tuning pin. The pin IS =
flexed down
while there is string tension on it.<SPAN
class=256013919-30112001><FONT face=Arial color=#0000ff
size=2> </FONT></SPAN></DIV>
<DIV><SPAN class=256013919-30112001><FONT face=Arial =
color=#0000ff
size=2>" Considering the forces in action (distance from =
block or
bushing, diameter of tuning pin and string tension) I wonder =
how much
the tension could deflect the pin (In other words, I don't think
so)."</FONT></SPAN><BR><BR>The tricky part is understanding how the =
tuning
lever is acting on the pin. When the string moves during the =
raising
of pitch the forces are no longer in balance. At the =
very least
(if the force of the tuning hammer is imagined as a person =
pulling
on another string wrapped around the pin the other direction) =
, the
rotational friction between block and pin and the tension of =
the
string have been overcome. If the string is moving (raising =
pitch) has
the vertical tension also been overcome? The =
solution is complicated by the fact that the force from the =
tuning
lever is off center because it has one handle. Which direction =
is it
being pulled from? Usually the from right but the variations in =
lever and
arm position could cause upwards or downwards forces to act on the =
pin. The
technicians arm position may also not be in line with the rotation =
of the
pin (though it should be as close as possible) which is probably why =
this is
more of a vertical piano problem than with a grand. Ever try =
to break
a lug nut free with a tire iron and have it come flying off into the =
ground?
That's because (like the tuning lever) the forces are not =
applied
purely as torque or tangentially to the pin. <FONT
face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=256013919-30112001> </SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=256013919-30112001>" </SPAN><SPAN
class=256013919-30112001> This is why I would never use the =
long tuning
tips that I've seen on the
market "</SPAN></FONT></FONT></FONT><BR><BR>The school of =
thought of
"tweaking " the pin back down into its resting position believes =
that the
pin has been relaxed from its flexed position during the tuning. =
A
third hand to play the note and a T handled tuning wrench with the =
other two
hands on it is what we need. Or a physics (mechanics)
major.<BR><BR>Sorry for the lengthy diatribe.<BR><BR>Jon =
Rhee<BR>Weymouth,
MA<BR><BR><BR></DIV></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>