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<DIV><FONT size=2>Roger:</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>It is a Steinway from the 1980's and its a bit of a
mess. Sharps and naturals have different key ratios (oops). =
The
Renner wippens I put on have a higher profile which forces the capstans =
a bit
lower, but it actually put the cap/heel contact more on the convergence =
line
than it was. I wonder if a longer knuckle radius would result in a =
faster
rate of acceleration through the swing arc. And if it does, =
would
that contribute to a feeling of less control because once the static =
friction is
broken the key would accelerate more easily, i.e., it might feel like =
the key is
flying away from you too fast? Just a thought.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>David Love </FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A title=baldyam@sk.sympatico.ca =
href="mailto:baldyam@sk.sympatico.ca">jolly
roger</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A =
title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">pianotech@ptg.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> August 25, 2001 3:19 =
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: hammer =
acceleration</DIV>
<DIV><BR></DIV><BR>Hi
=
David,<BR> &nb=
sp;
The Abel shanks are lighter than the Renner, this can add to you
observations. Also no graphite depending on the humidity in your =
area,
this can be a significant difference re friction. These are the =
two
reasons I prefer the Abel shanks.<BR>It's been a while since I used =
Renner
shanks, so things may have changed.<BR> I have not noticed any =
thing
amiss with any of Wally's knuckles with regards to friction, and I =
know he is
very vigilant with regards to dimensions, alignment and =
friction.
He gets a lot of feed back, so talk to him, he may have some extra
ideas.<BR>Is this a Steinway? If so the capstan and heel =
geometry is
critical. 1mm change can mean a whole lot, so check =
carefully.<BR>Just
some random thoughts.<BR>Roger<BR><BR><BR>At 11:48 AM 8/24/01 -0700, =
you
wrote: <BR><FONT size=2>
<BLOCKQUOTE cite type="cite">Roger/Newton:</FONT><BR><FONT
size=3><BR></FONT><FONT size=2>In this case it is new =
parts. Renner
wippens, Abel shanks. Center pins are fine everything is =
lubricated
properly and adequately. I am aware of the static friction =
element but
it seems more than that. I do notice that the leather on =
the
Abel shanks is much different than the leather on Renner shanks, =
which I
have generally used in the past. The Abel knuckles seem not as =
smooth
and soft as Renner's. Any comments on that? =
</FONT><BR><FONT
size=3><BR></FONT><FONT size=2>David Love</FONT>
<BLOCKQUOTE><FONT size=4>
<DL>
<DD>----- Original Message ----- <FONT size=4>
<DD>From:</B><FONT size=4> <A
href="mailto:baldyam@sk.sympatico.ca"><FONT size=4>jolly =
roger</A><FONT
size=4> <FONT size=4>
<DD>To:</B><FONT size=4> <A =
href="mailto:pianotech@ptg.org"><FONT
size=4>pianotech@ptg.org</A><FONT size=4> <FONT size=4>
<DD>Sent:</B><FONT size=4> August 24, 2001 10:13 AM<FONT =
size=4>
<DD>Subject:</B><FONT size=4> Re: hammer acceleration<BR><BR>
<DD>Hi David,
=
<DD> &nb=
sp;
Are you noticing this on new parts? Once static friction =
is
broken, I have noted that this happens more frequently with worn =
or
loose keybushings. e.g. Changing a prehung set of Yamaha =
shanks,
with out rebushing keys. At one time I used to change just the =
hammer
sets at the University. Now I insist on rebushing keys =
along with
hammer replacement. It makes a big difference.
<DD>If the friction is high on the knuckle and centre pinning =
friction
is very low it can give similar results. To trouble shoot. =
Remove
a hammer and wippen assembly, and measure the friction of =
the
flange C/P's, Holding the flange horizontal, if it drops under =
it's own
weight, will give you a quick check, but start measuring and =
repinning
if there seems to be problems. This eliminates these as the =
cause. Next
examine the capstan, and wippen cloth, polish the capstan, =
and if
it's old capstans steam out the cup, dry iron smooth, and =
burnish in
some teflon powder.
<DD>FWIW. I have repinned more than one set of flanges on new
parts.
<DD>With friction happening with the right amounts in the right =
places,
the key should go down nice and and steady. Many new Korean =
pianos have
way too much friction on the knuckles, shrinking the C/P =
bushings has
been a common practice to over come friction. It will mask =
the
problem, and give acceptable DW readings. Change the =
knuckles, and
WOW, watch the the friction figures change.
<DD>To to look at geometry issues you have to start with the =
magic line,
key ratio, etc.
<DD>The old adage, "divide and conquer", applies here. =
Just
eliminate one thing at a time.
<DD>Regards Roger<BR><BR><BR><BR><BR><BR><BR><BR>
<DD>At 09:00 AM 8/24/01 -0700, you wrote: </FONT><FONT size=2>
<BLOCKQUOTE cite type="cite">
<DD>I notice, when I am doing a weigh-off on a key board, that =
on some
actions as the hammer rises the acceleration is relatively =
slow and
steady. Other times, once the hammer starts to rise, the =
acceleration is quite rapid. What is responsible =
for that
difference? Friction would seem to be the logical =
answer, but
friction where? I heavily lubricate actions before I do =
a
weigh-off. There seems to be something else at work in =
the
geometry/leverage. Among other things, with the rapidly
accelerating hammer, it is more difficult to determine the =
measured
downweight. I there any way around that problem?
</FONT><BR><BR><FONT size=2>
<DD>David =
Love</FONT></DD></BLOCKQUOTE></DD></DL></BLOCKQUOTE><BR><BR>
=
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