[pianotech] Pianos that have frequent broken strings

[Paul T Williams]

Hi Mike,

On the Knabe.(I know, Aeolian!)

Yes! the flattened and grooved hammers are contributing a great deal!!. 
There's too much hammer hitting the strings, and reshaping (if there's 
enough felt left) will reduce that a great deal.  It sounds like new 
hammers are called for, unless you can re-shape them to a more "Steinway" 
style.  I'm replacing some on a Steinway B in a piano faculty studio where 
the capo is fairly good, but the hammers have a 1/4" groove in them.  I've 
been replacing strings a lot!  Im making this professor deal with only one 
of his two B's for a time to replace the hammers.  Tired of going up there 
to fix it and there's nothing left to file away....

The flat and grooved strings will also contribute to the bass string 
breakages.

Try to sell them a hammer replacement.  Just filing old worn out hammers 
is like putting a bandage on a broken arm!  It will be fine for a while 
and then come to haunt you again. But, if there's plenty of felt left, by 
all means reshape them! That'll buy them a little time to save up to 
replace them.  If these are original hammers, then it's passed due for new 
ones!

My cent and a half....(inflation don't you know!) ;>)

Paul





Mike Erickson <merick1948 at yahoo.com> 
Sent by: pianotech-bounces at ptg.org
02/03/2009 03:29 PM
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Subject
[pianotech] Pianos that have frequent broken strings







Only a few particular pianos come to mind (over the last 28 years). 
The latest is a 1960   about 6'3" Knabe grand on a high school stage (plus 
it's twin at another high school)
 
The strings rarely bust during a tuning, but sometime inbetween tunings.
Since January 2006, 3 wound strings have broken, and 12 treble strings, 
all terminate and break under the de cappo bar,  and most in the 2 highest 
octaves.
 
The breakage is accelerating.  It does get played quite a bit.  Mirror 
inspection of the decappo termination shows a little nitch (which I have 
been lightly filing at each replacement) and a fairly defined point (as 
opposed to a more rounded termination point).
 
I don't know how much the flattened & grooved hammers are contributing. 
Monies have been tight over the last decade, and maintenance beyond tuning 
and obvious repairs has been put aside.  In the upper two octaves, 
rounding the flattenened hammers would bring the stike point maybe 1/16" 
to 1/8" from the inner felt, in-other-words, it would probably be the last 
shaping the hammers could receive before cutting through the white felt.
 
Has anyone have a significant improvement in curtailing frequent string 
breakage with simply hammer shaping/voicing? 
 
I'm sure this beatup instrument is ready for replacement or at least 
rebuild, but if any of you have already been experiencing a similar story 
on this era of Aeolian built Knabe, I would appreciate knowing if anything 
you tried, helped out temporarily,  or if nothing worked.
 
I've also encountered "string busting pianos"  that were much younger than 
this. 
An 80s Kimball console, 
( 2) 1985 Young Chang grands, 
1987 Wurlitzer studio (even my replacements bust within a year or two) , 
and to a lesser degree a couple of older Yamaha consoles.
 
Any shared experiences appreciated,
 
Mike, Tucson Arizona

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