[pianotech] String breakage

[David Love]

I don't think the bends weaken the string any significant amount.  Why would
it?  Wire bends, it isn't particularly brittle.  The breaks that occur at
the bends are more often due to friction at the bearing points and increases
in tension in one segment when the wire doesn't render through those points
easily, not because of the bend itself.  

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of pnotnr at aol.com
Sent: Tuesday, March 02, 2010 6:49 PM
To: joegarrett at earthlink.net; pianotech at ptg.org
Subject: Re: [pianotech] String breakage

 

Thanks, Joe

You're right about the typical breaking %, but my point was just that the
bends we put in the wire are weak spots and are closer to the breaking
point.  So that even though the Mason & Hamlin 9 foot string AO calculation
you mentioned puts it at 75%, the bends in that string must be closer to
100%.

Gordon Large, RPT
Maine

 

 

 

-----Original Message-----
From: Joseph Garrett <joegarrett at earthlink.net>
To: pianotech <pianotech at ptg.org>
Sent: Tue, Mar 2, 2010 5:01 pm
Subject: Re: [pianotech] String breakage

Gordon said: "When a string is at pitch, it's usually around 60% of the
tension that would cause it to break."

 

Gordon,

That is a false statement for the most part. Most strings are in the 35% to
55% of breaking strength @ pitch. There are exceptions, but are generally
few and far between. Most Yamaha scales are "High Tension Scales", so you
will find that string breakage is more common, especially with the U.S. made
versions. The example of a 1900 So/so Grand and how far one had to twist the
t.pin to get the string(s) to break, was an example of a Medium or Low
Tension Scale. 

Just FYI, the thicker the soundboard and the stiffer the soundboard assembly
is, the higher tension and the harder the hammer is required to get decent
(?) sound production. The best example of a string that WILL break, is the M
& H 9footer - A0. That string is at around 75% of breaking strength, at
pitch and WILL break. (Soooner than later! <G>)

Regards,

Joe

 

 

Joe Garrett, R.P.T. (Oregon)

Captain, Tool Police

Squares R I

 

 

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