Bridgetop Extravaganza Revisited

[Farrell]

I'll be very interested to hear the recommendations for this one. I don't have a lot of experience - so don't do anything based on what I say. But that won't stop me from typing away here! It just seems this is clearly a case for recapping. This is assuming there is crown everywhere in the board, and no killer octave region.

I would have concern about the epoxy adhering to the small string depression. This is likely a highly polished, smooth, and compacted tiny area of wood. If this were a 1922 4' 8" Brahmbach, it might be worth a try. But on a 16 year old Dumbo? Good epoxy adhesion often requires good surface preparation, in much the same manner that good surface preparation is the foundation for good refinishing results.

Is it not logical to think that anyone that can shell out the dough for a new or recent model D, cough up the bucks for a proper recapping?

Terry Farrell
  
----- Original Message ----- 
From: "Stephen Bellieu" <sbellieu@mindspring.com>
To: <pianotech@ptg.org>
Sent: Wednesday, December 18, 2002 5:13 AM
Subject: Bridgetop Extravaganza Revisited


    Hi All,  
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)  
    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? 
    Looking forward to peoples responses.

    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.  

Thanks,  Steve Bellieu