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<DIV><FONT size=2> Hi All, </FONT></DIV>
<DIV><FONT size=2>Just joined, first post to this or any other
group. Serendipitous timing, just read all the recent =
bridgetop/
bridgepin posts. Have a 1985 Stwy D in the shop for action =
overhaul and
restring. I thought I was noticeing something funny about the =
bridges but
was in denial until I started taking all the teardown notes.
The plain wire strings have been pounded (seated) into =
the bridge
so that at the edges there is more wire diameter below the =
bridge top
than above it. When viewed from the side the wire makes a =
pronounced
curve up onto the bridge and down again out the rear making accurate =
component
readings impossible to do from on top of the wire. It =
was
showing negative front bearing until I realized what was happening and =
started
using the actual bridgetop as reference. Situation is most severe =
at capo
sections and diminishes down to what looks like normal grooves to =
me under
the bass strings. Deflection in strung piano is .5 deg at =
bottom of
low capo, 1-1.5 deg rest of capo sweeping up to 2.5 deg at =
note
88. There is .250" crown at low capo. (measured from top of
board) </FONT></DIV>
<DIV><FONT size=2> Is it possible this condition is =
due to the
quality of the capping material? I usually work on much =
older
instruments. I have never seen string cuts like this. Also =
the
various pressures have caused dead wood to swell up and check here and =
there
around the terminations. Again I'm not used to seeing this.
Inspection of the pins under magnification shows the string =
resided in two
distinct locations. My theory: Pre- and Post
Pounding. There are also a lot of unexplainable nicks on the side =
of the
pins. The pins pull out easily. No cracks to speak of. =
</FONT><FONT size=2>This is an institutional piano which has probably =
been in
Southern California its whole life.</FONT></DIV>
<DIV><FONT size=2> What I'm thinking about doing is =
similar to
what Dale Erwin just posted. I've never done the epoxy bridge =
thing but
I'm familiar with the nasty stuff. I'm imagining thickening it enough =
with
colloidal silica so it won't run down the notches or too much into =
the
holes and applying it with a small spatula. I want to fill those =
deep
grooves (at least on the speaking side) and then sand the top =
flat. If I
put the stuff on in the morning can I pare/renotch and redrill at the =
end of the
day before it gets too hard and while I can still find the original
holes? </FONT></DIV>
<DIV><FONT size=2> Looking forward to peoples
responses.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2> I want to stop using the misnomer =
"string
seating" in favor of wire straightening (or something similar) =
which is
what I do at a low lateral angle (around the bridges anyway). =
I have
never been convinced of the need of downward tapping pressure at the
bridges. For some reason this is one of the first things new =
technicians
are taught and the thought of them going around with little hammers =
and
pounding on pianos scares me. We straighten wire for control of =
damper and
hammer contact and for quick stabilization of new strings. Perhaps =
having
the wire come straight out of the bridge helps the string to vibrate in =
a more
perpendicular plane even. I don't really know. After you =
take a few
pianos apart you find that even in a negative bearing =
situation
the angled pins hold the string tight to the bridge. If there =
is so
much negative bearing that they don't then no amount of pounding will =
hold them
there. But I guess that is another thread. Right now I =
need
help getting out of this mess. I have finally accepted I have to =
pull the
plate. So much for the quick restring of a fairly new =
instrument.
</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Thanks, Steve =
Bellieu</FONT></DIV></BODY></HTML>