[pianotech] scaling

[David Love]

You need to provide the speaking lengths for the whole scale to have it
calculated (mm's is better).  Where there are 4 hitch pins per two notes I
would guess that it's really 2 hitch pins per one note and that one is a
single.  Once the scale is calculated then you can fit the even or odd
number of notes per gauge to the available hitches in that section.  

 

Maybe you can post the formula you are using on a single string that is
yielding an incorrect tension level so we can see what you are doing.

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Larry Fisher RPT
Sent: Tuesday, July 28, 2009 2:13 PM
To: pianotech at ptg.org
Subject: [pianotech] scaling

 

I have a Hardman 5 foot 7 grand that was destrung and the scaling notes were
lost.  My job is to reconstruct the scale to fit the plate.  (I have the
bass strings and the number of wound strings matches the number of hitch
pins for the bass bridge) This sounds easy enough but there's about half of
the tenor or middle section that is 3 hitch pins per two notes and the other
half is 4 hitch pins per two notes.  That sounds easy enough to overcome as
well however I'm trying to get a way point, a bench mark, an indicator on
string size for a few notes in that area, specifically in the lower part of
the scale (just above the bass strings).

 

Ok so I refer to some books, pull out some formulae and get garbage for
results no matter what formula I use.  I even got my nerdy brother to help
and I'm afraid that just generated more questions and no foward movement.
(he's an engineer)

 

"The Calculating Technician" and "A Restringing Guide" are two books I've
pulled formulas out of so far.

 

A440 note number A49, length of 15.75 inches and A220, note A37 length of
29.375 inches are two notes I've used just to get the formula up and
running.  I should have a string tension of somewhere in the neighborhood of
160  (155 to 170 roughly) and I'm so far off using ANY formula that there's
something amiss somewhere.

 

B27 is 43.675 inches

F33 is 34.75 inches

C40 is 24.675

F45 is 18.375

C52 is 13.25

 

>From there on up the scale is about the same as any other grand.  (using a
four six or six four method)

 

If someone has a formula that WORKS I'd appreciate some help here.

 

Ready to scream in The Coov.

 

Lar

 

 

 

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