Soundboard drydown for installation

[Erwinspiano at aol.com]

Hey Jude

Hail Dale, (Sorry had to return the rhyme), et  al,
 
I come from the land of a very strict adherence to the  doctrine of CC 
boards. Speak up if I offend any neighbors here on the  list, but I think I am the 
only heretic in this part of the land that has  abandoned the CC for a hybrid 
and even gone as far as experimenting with the  RC & S. 

  You heritic

Currently, I have settled on a hybrid. I think the  primary reluctance to 
abandon the lower ranges of MC (3.5-5%) has to do with  the knowledge that most 
households here range from RH in the low teens in  winter to the high 80s in 
the summer. We just can't count on our customers  maintaining the RH in their 
piano room, hell we're lucky enough if we can get  them to move their $80,000 
investment away from the fireplace, heating  register, window and exterior wall 
(like my piano for example, not the price  just the situation).

    With the Sitka that you are using your  boards stand a way better chance 
of surviving than the Much softer varieties of  spruce such as the white 
boards that Or Eastern spruce.  At 5% emc when  ribbing and crowning ribs you have 
a great sounding piano with less opportunity  for damage.
 
 

We know our wood can withstand the compression set of the  expanding board 
better than the contracting board so we ere on that side and  deal with the 
compression ridges. Udo Steingraber also mentioned that their  drying schedule had 
more to do with protecting the wood from the driest  environs than promoting 
crown. Some speak of the ethereal qualities and tonal  color that only a CC 
board can yield but I'll leave that one alone  :).

  I've heard many incredible sounding C.C. soundboards of  many ages. The 
point of course as stated many times is we strive for greater  Reliability and 
predictability.  This is the reason we are  trying new techniques. 
    The C.C. panel is a very strong structure  when built this way & that 
stiffness is IMO vital component to producing an  even sounding scale. If too 
much compression is left out of a C. C design but  the old ribbing pattern is 
retained the possibility for board resonates are  greater. I.e.Such as a weak not 
on a c sharp 52 & the next note is  strong.  We all hear these anomallies in 
most pianos.  Our goal  as board builders & designers is to eliminate them 
with our methods &  materials.

 
Using my handy-dandy "Crownulator," [see archives] the other  thing I've 
noticed is that my traditional CC brethren, that rely on low MC and  forced 
crowning (i.e. in a dish) to promote crown, end up with way more crown  than they 
thought. Their go-bar decks may measure 60' radius, but by the time  the board 
is glued in, they usually have about a 35' to 40' radius which  is more than 
what I've seen in some rebuilders' boards that are pre-crowning  their ribs, 
unless of course they are using a more ambitious radius in their  rib scale from 
the get go, as I am. This is all measured in  the unloaded state across the 
grain. Loaded states are even more  interesting, but I would like to collect 
more data before making any  statements.

  Yes more initially but even my own practice I can see a huge  belly before 
it goes in but as the board conforms to the rim some of that extra  crown 
disappears. I think the numbers of radii you state are fine.  I've  introduced 
some pretty steep crown with my methods/press/ribs with no  adverse results.  How 
much is too much.  I dunno

    
 
 Still, I won't be happy until I can say that  this species of wood with such 
and such modulus of elasticity, given x  amount of load, with y rib scale and 
design, and so and so's hammers yield  this type of sound. Yeah, dream on...

  Yeah...Well said Jude.  I have other  thoughts about the crowned bridge 
stuff.  Maybe there issomething to it  that we just can't quantify.  Yes I know 
the idea has been thoroughly shot  down on list & we can agree to disagree but 
I can think of one board I  did that had a real sparkle to it when I did this. 
 Not only that but the  board set right into the piano & the trebles & bass 
corners didn't  require the requiste stress to get them down on the rim. Yes 
there is a slight  bending stress that is introduced along the grain but is that 
a bad  thing.....  Is it a positive  thing?  Perhaps
    its' like the little Mason  & Hamlin Crown demonstrator jig where the 
thin piece of spruce is bent along  the grain & then the sound suddenly come to 
life.  Aye?
  Many folks do it this way who have decades  of practice.  My Motis operandi 
has always been try stuff &  listen.  Then I get to decide for 
myself......Ain't it  great?
  Dale

 
Back to work,
 
 


 



**************Start the year off right.  Easy ways to stay in shape.     
http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20080122/2f718c5b/attachment.html