Soundboard rib question

[David Love]

I don't know if people will answer specifically as you haven't provided
enough data and these things need to be calculated.  The question I would
ask, though, is if you want to "beef up the ribs" then you are changing it
and if you are going to change it then why not just change it.  Have a rib
scale calculated based on the scale design (which can be kept original in
terms of its overall tension) and address the issues that you want addressed
in the redesign.  I don't think anyone will be able to give you a "beef up
the ribs by x" answer.  

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf
Of Ric Brekne
Sent: Saturday, January 21, 2006 7:11 AM
To: pianotech
Subject: Soundboard rib question

Hi folks...

Despite knowing that the major rebuilders are probably not going to 
answer this because they dislike my foul rotten guts (for some 
mysterious reason... :) )  I will put this to the forum anyways, hoping 
to get some insights.

I have this first year production Bluthner straight strung that I am 
getting ready to pull the soundboard out of.  One of the options I am 
considering is to alter the ribbing system on this.  The instrument 
measures about 195 cm, and has only 6 ribs. These are not very 
substantial ribs at that... The ribs are wide and short and get taller 
in the middle and have a  _^ shape as opposed to a rounded shape..  28mm 
wide, 9mm tall along their sides, 14 mm tall in the center.   There is a 
long extra "rib" that runs roughly parallel to the bridge and crosses 
over the cross grain ribs as well.  It measures 55 mm wide and 15mm tall.

I suppose given the dimensions of the existing ribs this was a so called 
<<natural>> crowned board in its time (ie compression with flat ribs in 
a flat caul). My question is just how much beefing up of the system is 
advisable ?  I am assuming  the amount of downward force on the board 
was significantly less then present instruments have.  I want to try and 
keep close to the origional sound picture these instruments had but at 
the same time I want the thing to be structurally strengthened (if 
necessary) and try and create a bit cleaner treble then fortes I have 
heard typically have.

I could just pack the thing off to Bolduc and get a re-creation.... a 
nice easy option I suppose... but before I do that I wanted to hear what 
some of you think.

I will be greatfull for any replies.

Cheers
RicB


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