A string's treatment

[Isaac OLEG]

Stephen,

I have not explained really well what the method is.

The question is not to go slightly above the plastic deformation
limit, but to stay near the zone, but slightly under.
Then there is a transformation of the string that is well known in the
metallurgic trade I was said.

This is to obtain the plastic deformation that happens with time, but
under the normal elastic limit, and at once.
If the deformation occur obove that, thats bad indeed (and immediate
as you said), we just want to get the slack off the string.

You say :
The tensile properties of high quality music wire should
> be: (1) high uts consistent with desired working stress, (2) yield
point as close to uts as possible, and (3) sharply defined transition
to plastic  deformation. It's quite difficult the make wire with all
of these  properties - modern patented high carbon steel music wire is
a  marvellous product that is too often taken for granted. If you look
at something like Roslau wire you get a yield point of  about 2200MPa
with UTS of 2400MPa [these values are typical]....yield may begin a
> bit lower, but the sharp dive is around these typical values. There
is no room in that tensile curve for the sort of "conditioning"
described, so whoever is doing it is using bad wire to  begin with.

We see no interest in having yeld point as close as uts, seem more
than dangerous to us.

You give us values as 2200 and 2400 Mpa, what are they from ?
I was explained that these value are looking like the values for the
Phosphored iron strings you wish to produce.

The actual value for elastic limit of Roslau wire is 80%(approx) of
the breaking strain as checked by an independent laboratory once
(other tests will be made in the fall this year.

Beside, I was amazed you have find yourself aggressed because you
fairly know who is Stephen Paulello, so in the same post you say he
use bad wire/bad scaling, with a little complement to Malcom Rose.
There was absolutely no marketing or commercial in my post, Stephen
tells that if you are able to provide the famous strings you say you
will produce, he will be the first to be happy to try them - same for
the model on piano action.

What a world !

PS Beside, your comments are true when it comes to the plastic
deformation, that is not what we want to obtain.

Another comment : the fact that a major third is used to begin with is
applied to the "standard piano scaling" with lower tension values near
the break. Indeed it may well be computed before acting, but I was
said that we have margin for error, unless the high treble is yet much
sollicited.

BTW, Joe, we checked the scaling of a little grand Shimmel, with 55 mm
at c8 and 93% of breaking strain (at 442 pitch) this is  not really a
low tension scale, other octaves give us values between 75 and 85%
breaking strain. where do that appreciation comes from ? (other models
may be ?)

Greetings

Isaac OLEG

Entretien et reparation de pianos.

PianoTech
17 rue de Choisy
94400 VITRY sur SEINE
FRANCE
tel : 033 01 47 18 06 98
fax : 033 01 47 18 06 90
cell: 06 60 42 58 77

> -----Message d'origine-----
> De : Stephen Birkett [mailto:sbirkett@real.uwaterloo.ca]
> Envoye : mercredi 9 juillet 2003 07:01
> A : oleg-i@wanadoo.fr; Pianotech
> Objet : Re: A string's treatment
>
>
> Isaac wrote about wire:
> >I come back with this post that you may not have noticed. It is a
> >prcocess to produce some sort of annealing on new strings
>
> well no, not  annealing which is done by heating the wire. The
> process being used here is a mechanical manipulation.
>
> >if you want the strings to sound more brillant, may be they may be
> >aged (other strings as well)
>
> Sounds like cheese or wine-making, not wire-making... I don't like
> the method for music wire as described. Presumably, the
> procedure is
> being applied to raise strings past their elastic limit but
> below the
> ultimate tensile strength (uts). This would tend to enhance
> stability, but only if the working stress on the wire is
> too close to
> uts to begin with, either because of bad scaling or bad
> wire. And the
> result is a second-rate tonally-poor wire in my view.
>
> Isaac, methinks you had a song and dance from your
> wire-maker friend
> about this, or at least whoever told the original story is playing
> fast and loose with the metallurgical facts with a dash of
> salemanship thrown in. There is some basis in reality but
> not a good
> one in my view.
>
> The tensile properties of high quality music wire should
> be: (1) high
> uts consistent with desired working stress, (2) yield point
> as close
> to uts as possible, and (3) sharply defined transition to plastic
> deformation. It's quite difficult the make wire with all of these
> properties - modern patented high carbon steel music wire is a
> marvellous product that is too often taken for granted. If you look
> at something like Roslau wire you get a yield point of
> about 2200MPa
> with UTS of 2400MPa [these values are typical]....yield may begin a
> bit lower, but the sharp dive is around these typical values. There
> is no room in that tensile curve for the sort of "conditioning"
> described, so whoever is doing it is using bad wire to
> begin with. It
> is  undesirable anyway to stress wire beyond its yield point - this
> does  raise the yield point to some new value closer to UTS, and in
> fact the deformation is actually almost instantaneous, so
> there is no
> need for the hours of sitting of original yield point, if you did
> want to do this. Why undesirable? Well, in my view, the sort of
> "brilliance" you could achieve this way is metallic, almost
> unpleasant - plastically stretched wire is metallurgically quite
> different from drawn wire. I can see why it might be resorted to in
> some cases, for instance if the wire product being used is not
> properly drawn as music wire, and yield point is too low in
> relation
> to UTS [but the result will always be second-rate]....this is the
> problem with all Rose wire for instance. Or I can see it being
> resorted to because of a bad scale with working stress too close to
> yield point, but not really a good solution. Better to use better
> scaling more appropriate to the wire product being used. I can also
> see it being used as a bandaid solution to fix wire which has a
> shallow transition to plastic zone from elastic, instead of the
> desirable sharp transition, as I expect is the case with many
> subsitute "low tension" wires [although I haven't tested many of
> these wire types yet]. In all cases it is better to fix the
> problems
> at either the design level or the wire product level, rather than
> tinkering with the mechanical properties of the wire by
> stretching it.
>
> >comments welcome.
>
> Hmm. Not sure I said what you were hoping to hear Isaac....
>
> Stephen
> --
> Stephen Birkett Fortepianos
> Authentic Reproductions of 18th and 19th Century Pianos
> 464 Winchester Drive
> Waterloo, Ontario
> Canada N2T 1K5
> tel: 519-885-2228
> mailto: sbirkett[at]real.uwaterloo.ca
> http://real.uwaterloo.ca/~sbirkett
>