chickering quarter grand-re-scale trichords

[Fenton Murray]

I have no idea.
Fenton
  ----- Original Message ----- 
  From: Greg Newell 
  To: 'Pianotech List' 
  Sent: Tuesday, July 22, 2008 3:22 PM
  Subject: RE: chickering quarter grand-re-scale trichords


  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 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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