Bridgetop Extravaganza Revisited

[Tony Caught]

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Hi Jon,

Tools we are all interested.  Yes please would love to see it.

Regards  Tony

Tony Caught
Darwin Australia
caute@bigpond.com
  ----- Original Message -----=20
  From: Jon Page=20
  To: Pianotech=20
  Sent: Wednesday, December 18, 2002 9:48 PM
  Subject: Re: Bridgetop Extravaganza Revisited


  I wouldn't trust a shallow fill of epoxy to resurface the cap, recap.

  As far as pounding the string, I agree that it is over-rated and have
  tapped the bridge pins as Roger Jolly suggested to relieve false =
beats.
  I also devised a tool for removing the natural curve from the wire at =
the pins
  to improve the termination. I posted to the list a few years ago about =
it,
  I have a jpg file if any one is interested in viewing it.=20

  Regards,

  Jon Page

  At 02:13 AM 12/18/2002 -0800, you wrote:

        Hi All, =20
    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) =20
        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.  This is an institutional piano which =
has probably been in Southern California its whole life.
        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?=20
        Looking forward to peoples responses.
    =20
        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. =20
    =20
    Thanks,  Steve Bellieu

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