Bridgetop Extravaganza Revisited

[Jon Page]

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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.

Regards,

Jon Page

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

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