Bridgetop Extravaganza Revisited

[Erwinspiano@aol.com]

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In a message dated 12/18/2002 2:14:21 AM Pacific Standard Time, 
sbellieu@mindspring.com writes:

>                Hi Steve

                        Nice posting. And what a problem  I worked on an 
older D that had a similar problem. Apparently Someone thought that seating 
(smashing) the strings into the top of the bridge was going to fix all false 
beats or something. I was in that case able to plane down to the bottom of 
the cut and renotch without ill effects. One note I'll add is that Ds with 
healthy crown also need adequate amounts of bearing to drive the board. 1 and 
1/2 degrees is a place to start.
  What a bummer. Bring the customer in and let em see it.
           Regards and nice to have you aboard
           Dale Erwin

>    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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