[CAUT] pre-stretching new string?

[Richard Brekne]

Hi folks

Had to respond to a couple things in the back and forth between Fred and 
Ron.

First... strikes me that most of the discussion about what constitutes 
"significant" in terms of metal creep is because Fred and Ron are 
talking past each other. Ron speaks from an engineering perspective... 
what formulas tell us etc etc.  Where as Fred is comming directly from 
the perspective of what happens to metal piano wire. And I agree with 
Fred here... the <<significance>> factor of metal wire in the two 
perspectives can very easily be two very different things. To put it 
this way... are the engineers who design suspension bridges going to 
take the kind of elongation it takes to cause a 50 cent change in pitch 
in the piano wire application of steel cable as significant for their 
purposes ?.... an open question that I think Fred is correct in raising 
and has not been directly addressed in reply yet as far as I can see.

As to the below bit... I would say to Ron, that while I agree entirely 
with him on this issue of soundboard vertical rise and fall... (for that 
matter I'd go further and discount bridge dimension in the vertical 
direction changes as unlikely too... due to the amount of increased down 
bearing even a 1 mm change causes... this despite the interesting point 
of the length change of the string segment on the surface such a rise 
would result in because of the bridge pin angles.)  ,,, In anycase... 
this is not something that is <<determined>> conclusively.  There are 
just those of us who think along these lines and have presented some 
fairly weighty evidence to support the view. But when this discussion 
last came up there were many who disagreed and stated outright that 
vertical rise and fall of the soundboard does indeed significantly 
effect pitch. 

Cheers
RicB

         >I do know that new strings drop in pitch over time on old
         > instruments with zero to negative bearing, in my experience
        (meaning wood
         > crushing probably wasn't a significant factor there).


    Wait a minute. We did this already. Why would wood crushing
    not be a factor with negative bearing? Hasn't it already been
    determined fairly reasonably that soundboard rise, or fall,
    isn't a significant (there's that word again - not absolute or
    exclusive, even if measurable) factor in pitch change? Isn't
    there still lateral pressure on bridge pins? Isn't there still
    longitudinal pressure on tuning pins? Haven't we all seen
    bridge pins that had been pushed back by string pressure
    enough to produce a visible gap between the pin and the side
    of the hole? Haven't we all seen in removed pinblocks how
    deeply indented the block is where the edge of the plate
    flange sat, and how detailed an impression of the plate
    irregularities is pressed into the surface? Haven't we seen
    tuning pins (lots of them) that had a very noticeable gap
    behind them where string tension through the years pulled them
    toward the hitch pins? How is that not wood crush, and how
    could that not be a very *major* factor in long term pitch drop?

    Be a skeptic, by all means, but hopefully with an eye toward
    accumulating better data, rather than discounting obvious
    evidence that doesn't fit the preconception.

    Just an observation of evidence needing processing.
    Ron N

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