RC&S question in general

[Fenton Murray]

I hope this doesn't quiet the recent belly chatter on the list. I've been 
enjoying it.
Fenton
----- Original Message ----- 
From: "Richard Brekne" <ricb at pianostemmer.no>
To: <pianotech at ptg.org>
Sent: Sunday, January 27, 2008 11:55 PM
Subject: RC&S question in general


> The debates around these different board types seem to have two distinct 
> aspects to them.  The first is and most obvious is the combatant aspect 
> where folks doing different board types go to no ends discredit the other. 
> They do about anything then topically confront the opposing sides views. 
> This applies to all camps pretty much equally as far as I can see.  I 
> stand here on the outside looking at a host of different designers, 
> builders, manufacturers asking the same questions and getting the same 
> basic message back.  "We know best... obviously the other guy is full of 
> hot air and you shouldn't listen to him"  And with few actual exceptions 
> from any camp, thats about as far as it goes.
>
> The other aspect is all the stuff going on about how soundboards actually 
> work that quite obviously far less is known then all, each from their own 
> perspective would have it.  Nothing could make this more clear IMHO then 
> the apparent total lack of anyone to be able to predict the load bearing 
> capacities of a compression reliant board. This is used on the one hand as 
> a criticism against compression reliant boards... but then on the other 
> hand these same critics can not account for the degree of compression 
> (beyond what humidity vs rib restraint) itself imparts into any panel at 
> all... including so called non compression reliant boards.
>
> It is easy to demonstrate that the initial support provided by a CC board 
> is far beyond what the rib structure itself is able to bear. Again... the 
> entire reasoning for building an RC&S board underlines this as the stated 
> goal in RC & S boards is to design said support into the ribs themselves. 
> This directly implies and recognizes that the stress conflict between the 
> compression of the panel and tensioning of the ribs in a CC board is what 
> creates the support and strength against downbearing at any given time. In 
> a new board, other relevant factors are knowns... or should be.
>
> The only unpredictability I see in any of this is the lack of anyone to be 
> able to describe in math mechanics terms the functioning of the rib 
> restraining against a glued panel wanting to expand due to a given 
> downwards force on the panel. If this was calculated... all the guess work 
> goes out of the compression reliant picture as it is the only <<unknown>> 
> factor.  We already know how beams work as beams.  We already know how to 
> figure what compression in the panel and tension in the ribs forms for RH 
> changes given known starting points for these.
>
> Personally... I don't give a hoot which kind of board anyone decides to 
> build. I'll try anything myself.  My only interest is to find out how 
> things work. Getting into some kind of crusade for one or the other type 
> is TMMOT a waste of time as history proves the hopelessness and 
> meaningless of such endeavor. The fact is...and this is a bold faced 
> fact... that experienced manufacturers have been building boards of all 
> types for 300 years... and there is no statistical grounds for doubting 
> the viability of any of the basic methods employed (when done so 
> appropriately) today .  Nor does that fact prevent, impead, or threaten 
> anyone from trying anything new.
> End of rant.
> Cheers
> RicB
>
>
>