[CAUT] Wire Stretch, was Hardness of termination vs string breakage

[Jeff Tanner]

On Apr 26, 2007, at 7:17 PM, Fred Sturm wrote:

> On 4/26/07 4:14 PM, "Jeff Tanner" <jtanner at mozart.sc.edu> wrote:
>
>> If plain wire does not stretch as much as we traditionally give it  
>> credit, how would one explain the great difference in pitch change  
>> from wrapped wire to plain wire as changes in humidity affect  
>> tension change?  Not just crossing from bass into low tenor, but  
>> it is just as much present when the first few strings of the low  
>> tenor are wrapped.
>>
>>
>> Jeff
>
> Hi Jeff,
>     Wrapped strings are much closer to breaking point/higher  
> tension than the neighbor plain wires. The lower tension wires take  
> much less change in any factor (length, deflection, tension) to  
> produce a given pitch change than the higher tension wires. Think  
> about how much turn on the tuning pin it takes to raise that lowest  
> plain wire 25 cents, compared to what it takes to raise the top  
> wrapped string the same amount. Think about the same comparison  
> when you are first chipping to pitch. Crank and crank on those  
> wrapped strings, where a single yank gets the plain ones to pitch  
> and past.

But which one stabilizes first?

>      There are other ways of saying all this, which are probably  
> more scientifically accurate, but this is the basic reason for that  
> large pitch change in the lowest plain wires compared to wrapped,  
> whatever might be happening in terms of SB rising, bridge growing,  
> bridge lengthening, overall case expanding, etc. At least, this  
> makes sense to me, and others seem to agree.

In other words, the plain wire is more "elastic"?

On Apr 26, 2007, at 7:11 PM, Ron Nossaman wrote:
>
> What could that possibly have to do with old wire stretching with  
> time, assuming that it did?
>
> Ron N

Because wrapped strings "stabilize" sooner than plain wire, but they  
both have the same bearing obstacles.  We all have had the customers  
who either bought a piano and never tuned it, or had it tuned a  
couple times and their kids quit taking lessons, and that was 25  
years ago.  If the piano was never tuned, the bass will be low.  If  
the piano was tuned a couple times or more, the bass will be much  
nearer to pitch, but the treble can drop 100 cents or more.  Last  
Sept. I was called to do a first tuning on 4 new Chinese pianos for a  
school.  I found the bass almost at pitch, or in some cases sharp,  
while the treble was as much as 75 or 100 cents low.  I did two, and  
sometimes three passes in the treble and left them all in very good  
tuning.  I was called back in December to retune one of them, and  
found it almost in exactly the same condition I'd found it the first  
time, as if I'd never tuned it the first time.  The humidity was not  
that much different.  We've been having mild winters the last few  
years in SC.  I just tuned a 12 year old Steinway B that was last  
tuned during the winter.  Bass was almost exactly perfect, treble was  
very flat.  Should have been sharp, right?  It will not be as sharp  
when I retune it in August, as it was flat just now.

I'm no physicist.  But it just seems like plain wire keeps on and  
keeps on stretching over the years.

Jeff
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