[pianotech] Breaking bass string

[John Delacour]

At 09:00 -0700 11/04/2011, Delwin D Fandrich wrote:

>It could also be that wire--generally--is tougher than it is given credit
>for. The formula commonly used by scaling and/or rescaling programs is one
>popularized by Al Sanderson and it is significantly conservative. I'm not
>sure what wire specifications he based it on but it gives a % of breaking
>strength that is considerably below that of actual test with both Roslau and
>Mapes IG wire.

There is only one fundamental formula for calculating the _tension_ 
of a string; it's not a question of opinion, and in my article at 
<http://pianomaker.co.uk/technical/string_formulae/> I extract 
practical methods from this one basic immutable formula.  If anyone 
reaches different conclusions from the same data, then they are 
making a mistake somewhere because the laws of nature do not change.

As to the strength of different gauge numbers of wire from various 
makers there is no absolute law, of course.  The only certain way of 
determining this is by repeated tests on a specially designed 
machine, such as those used by Pleyel and Schiedmayer in the tests 
carried out on competing wires in the second half of the 19th 
century.  Failing this we have to rely on the tensile strengths 
claimed by the wire makers.

I have emphasized that the maximum of 70% **of the figures I gave in 
the table I posted earlier** in this thread is the maximum that I use 
for bass string manufacture using Röslau wire and I know from very 
long experience that if this percentage is exceeded there is a very 
real likelihood of the string's breaking.     The evidence is 
presented to me weekly in the form of broken odd strings and broken 
strings in sets that I am asked to replace.  My bass strings do not 
break, and they also sound good.  In practice it is only for a small 
minority of pianos that I need to reduce tension with respect to the 
original tensions and experience seems to have taught hundreds of 
piano makers the same lessons as it has taught me.

At 09:11 +0100 11/04/2011, I wrote:
>surely the only question worth asking is, do these pianos produce a 
>better or a stronger sound in the high treble?

You didn't answer this question.

JD