R,C&S question

[Richard Brekne]

He Jude.

I found Rons answer a bit vague... no disrespect intended.  So I'll 
venture an answer if you dont mind.


    Forgive my density but...

You are not dense my friend :)


    What is it about the 6-6.5%emc at rib glue-up that causes the panel
    to be
    supported, all else being equal in terms of rib crowning & rib
    dimensions,
    panel thickness etc.?

It is the ribs themselves that support the whole thing. The panel is 
just what pumps the air around so we end up hearing the thing.  The MC 
level is decided upon to meet whatever climate conditions one expects so 
that the panel does not come under more then very moderate levels of 
compression at any given time... simultaneously so it doesn't crack 
apart during dry periods


    Is it a question of internal friction, stress and/or compression?

I dont know about internal friction in this context... but stress, both 
compression and tension are definitely a big consideration here.


    I've read notes from classes taught by Del and Ron N. and while I
    get the
    stiffer rib assembly, I don't get why the extra emc makes for a more
    stable
    soundboard?

I'm not really sure it is more stable per se.  There are some 
assumptions I've not seen proven as to the reactivity claims Ron just 
made.  The wood in the panel will respond to climatic changes just as in 
any board. In that sense at least all boards are just as reactive.  Over 
the long term tho... the RC&S board... will (if designed appropriately 
for the climate it winds up in) experience less compression set... and 
in that sense at least is less reactive.


    Please forgive me and refer me to the archives if I'm opening up a
    can of
    worms here!  :)

Its nothing we all haven't dug our grimy fingers in several times 
before... wheres the melted chocolate ??


    Jude Reveley, RPT
    Absolute Piano Restoration, LLC
    Lowell, Massachusetts
    (978) 323-4545


Cheers
RicB