Soundboard thoughts / questions

[Farrell]

> -- Load support for soundboards needs to run (roughly) perpendicular to 
> the bridges.

I wouldn't think that it needs to, but I suspect it is most efficient that 
way.

> -- Given a low enough tensioned scale,  this could be accomplished by 
> running the grain of the soundboard (roughly) perpendicular to the 
> bridges. Especially if that soundboard was laminated crowned in that 
> direction.

I wonder if there is an efficiency in concentrating soundboard spring 
strength by using ribs. Maybe building the crown support into the panel 
would make the whole soundboard too thick for optimal sound production. I 
don't know.

> Questions relating to the above:
>
> -- How do you calculate load bearing strength of such a laminated board ? 
> Any straight forward formulas ?

I know folks use load-bearing beam formulas - I suppose you could use such a 
formula if it doesn't break down as the "beam" gets very wide and very thin. 
I suspect you'd need to test the formula's efficacy anyway, so perhaps it 
would just be best to experiment and observe.

> -- What would be the needs and purposes for ribbing this kind of board 
> across the grain ?

I don't know.

> Perhaps this all sounds a bit off the wall... but I would apreciate any 
> thoughtfull answers.
>
> Thanks
> RicB

I've got a question or two myself. Grain angle. Most manufacturers have the 
grain running roughly 45 degrees to the belly rail, parallel to the long 
bridge and perpendicular to the ribs. Was this done to facilitate 
compression crowning the soundboard? I can see that grain running parallel 
to the long bridge would be the most efficient arrangement for compression 
crowning. What effects does grain direction in the various areas of the 
piano scale have on tone, sustain, dynamics or whatever a designer would be 
concerned with?

Terry Farrell