chickering quarter grand-re-scale trichords

[Greg Newell]

Fenton and list,

                Would that original gold colored wire be the same as the
phosphor-bronze used in harpsichords?

 

Greg Newell

Greg's Piano Forté

www.gregspianoforte.com

216-226-3791 (office)

216-470-8634 (mobile)

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Fenton Murray
Sent: Tuesday, July 22, 2008 11:57 AM
To: Pianotech List
Subject: Re: chickering quarter grand-re-scale trichords

 

Thanks Joe,

Excellent point and yet another that I hadn't considered.

I rebuilt a Schomacker grand that had a gold colored plain wire, original. I
have no idea what it was but I did save some. I did re-scale that piano in
PScale although I realize now I was unaware of the original tensions.

Fenton

----- Original Message ----- 

From: Joe <mailto:defaziomusic at verizon.net>  DeFazio 

To: pianotech at ptg.org 

Sent: Monday, July 21, 2008 10:01 PM

Subject: Re: chickering quarter grand-re-scale trichords

 

From: "Fenton Murray" <fmurray at cruzio.com>

Also, recently someone pointed out that changing wire sizes (plain wire) did
not change the breaking point % of a note. After a few sample problems in
P-Scale I confirmed this. This was really a forehead slapper for me. If this
is true, bridge re-scaling is the only option for changing BP %.

Fenton

 

From: Ron Nossaman <rnossaman at cox.net>





   Also, recently someone pointed out that changing wire sizes (plain

   wire) did not change the breaking point % of a note. After a few

   sample problems in P-Scale I confirmed this. This was really a

   forehead slapper for me. If this is true, bridge re-scaling is the

   only option for changing BP %.


On plain wires, yup. You can change tension, but to change break%, you gotta
change speaking length.

Ron N

 

Hi Fenton,

 

I pointed out the "constant BP problem" a week or so ago only after slapping
my own forehead repeatedly.  Unfortunately, slapping my forehead repeatedly
still left the problem intact and my cognitive abilities less so.

 

Ron is 99.99% right in his reply.  I don't think it will help you much, if
at all, but for logical completeness, I'll add that there is another way to
change break% instead of changing the speaking length:  change the wire
composition.  Stainless steel wire, or phosphor bronze, or yellow brass, or
anything else will have a different modulus of elasticity, density, and the
like, and these physical properties will change the break% when a given
speaking length is tensioned to the given pitch. Unfortunately, I know of
nothing available that will have a lower break% (meaning a stronger wire)
than modern steel piano wire.  

 

I'm only mentioning this for two reasons.  One is that, in working through
scaling formulae there is usually a constant that relates to the wire
composition.  If using a different type of wire, It is this constant that
would be changed.  It is pretty common to take constants for granted, and I
always remind myself to take a hard look at the "taken for granted" parts of
any problem when trying to arrive at creative solutions.

 

The other reason is that I'm hoping against all odds that one of the
engineers/physicists out there on the list might know about any modern
materials that might be investigated for higher strength/lower break%.  If
there are any out there that might realistically be tried (carbon nanotubes
are about a million times too expensive at the moment), I'd sure like to
know about them
.  

 

Joe DeFazio

Pittsburgh

 

P. S. - Personally, I'm guessing that breakthroughs in material science will
be the next big thing in piano design and rebuilding (though CNC routing and
machining is pretty exciting, too, as is 3D printing).

 

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