[CAUT] pre-stretching new string?

[Fred Sturm]

On 6/5/07 5:22 PM, "Ron Nossaman" <rnossaman at cox.net> wrote:

> "When an elastic material, such as steel, is loaded at
> ordinary temperature, it deforms in proportion to load almost
> simultaneously with the loading. Thereafter, the load may
> apparently act on the material for an indefinitely long period
> without causing any further appreciable change in dimensions.
> Even if the material is stressed above it's elastic limit,
> after an immediate deformation there appears to be no further
> change in dimensions until there is some change in load."
snip
> "At room temperatures, creep is of no practical significance
> in steels, but does reach measurable proportions in such
> metals as lead, tin, and zinc."
Hi Ron,
    I dunno. Those phrases "appreciable change in dimensions" and "no
practical significance" might be loaded (along with "measurable
proportions": who's measuring, and to what accuracy?). Could be "not
significant in 99% of all applications, but there's enough creep to cause
100 cents of pitch drop in piano strings over the course of a year, and
another 100 cents over the next 20." Just the skeptic in me, and, possibly,
years of experience. Of course, I could be wrong, and I could be
misinterpreting my "years of experience." But it sure would be nice to tie
down one of these people who write this kind of stuff and ask some very
precise questions. 
Regards,
Fred Sturm
University of New Mexico

PS In answer to the original question, I chip the piano to pitch (aurally,
rapidly), then chip to 25 cents sharp. I come back next day and chip again
to 25 cents sharp. Then conform the strings to the duplex and bridge pins,
using a brass tool of my own making, similar to the Wurlitzer "false beat
eliminator" sold by Schaff. This "conforming" work is done in a firm but not
jerky way. In some cases I slide the tool along the string toward the
bearing point. Other times I just lean hard - use the whole body as opposed
to a lot of arm strength.
    Generally the pitch is now a bit below standard. I pull again to 25
cents sharp, then conform strings to front bearing points, using a
Strate-mate, the same brass tool, and a string hook where needed.   Piano is
"reasonably stable" at this point. I prefer to give it a week or so to let
things settle before doing a reasonably fine tuning, then level strings,
then install dampers.
    I have been pleased with the results of this system over the years.
Seems to yield reasonably rapid settling - and it makes damper regulation
and hammer mating much faster. Doing the string leveling with a level with
the dampers out is fast and accurate.

    Actually, I guess that was the second question, about full stringing as
opposed to Mark Cramer's firsts question about 100 cents sharp. I sometimes
tune a replacement string 100 cents sharp, and come back a day or a week
later and tune it to pitch. Seems to work well for stability. In emergency
(before concert breakage) conditions, I'll tune to 100 cents sharp, do some
rapid massaging (conform to bearing points, but also heat the string), and
lower to pitch at the very last moment.
    Jim Arledge swears by tuning a full set of bass strings 100 cents sharp,
then coming back next day. He demonstrated that at Nashville, on the
convention hotel bar piano. (Talking about replacing only the bass strings,
not a full restring)