Downbearing Guidlines

[Porritt, David]

Have you considered Pure Sound wire?

dp

David M. Porritt
dporritt at smu.edu

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On
Behalf Of Ric Brekne
Sent: Friday, December 22, 2006 10:45 AM
To: pianotech at ptg.org
Cc: caut at ptg.org
Subject: Downbearing Guidlines

Hi experts out there...

Just a quick question I'm hoping for a few hints on.  Given a
soundboard that deflects from 4mm of crown to 1 mm of crown with 250 lbs
of presure spread over its surface roughly evenly....  what kind of
downbearing pressure should I be looking at achieving. Said another
way.... what kind of string tension should I be looking for.  The scale
I am working with is a very low tension scale with plain wire breaking
%'s around 35 %. with modern wire used as a base for figureing.  I'm
thinking that an increase to 45 % should be perhaps a minimum.  The
scale needs to remain quite low tension because of structual concerns..

Thoughts ?

Cheers
RicB