laminated ribs

[Erwinspiano at aol.com]

Dale,
Those ribs were originally built into a CC board. How can  a 
compression crowned board get mechanical support from the rib 
scale,  however "good" the scale looks? The ribs in CC boards 
resist the crown  that panel compression is trying to form and 
maintain, and just put more  compression load on the panel.  -----Ron
 
  No, I get all that Ron, but if the ribs are built significantly  taller & 
of stiffer material by design  then more panel  compression can be taken out of 
the equation.  Another thought is, &  I've witnessed this quite a few times 
is, that Stwy A's (1 & 2"s) in  general can produce a pretty wonderful sound 
even with a  flat or  flattish board providing there is some small but 
consistent bearing load  still intact so in this case it would seem that there are 
enough impedance  factors about the rib scale to make the system work rather well. 
Ok maybe a  freak of nature but it happens fairly frequently.  
   About 5 years back I had such an long A I was going to  resell it. It had 
Steinway hammers which were quite soft &  made  it sound really good.  It was 
hard to imagine that a new board would make  it sound much better. It truly 
sounded glorious but it was a spec job  & I don't sell old boards very often. I 
didn't do any thing to the  action until later for a really good A b 
comparison.
   So  I built a board with the same number of ribs  making them crowned at 
about 60 ft. Made em taller but not much. Used sugar  pine in the bottom & 
yellow pine in the top.  The sound was  cleaner and the sustain was about the same 
which was awesome.  It just  had it!!
  I attribute much of this to the original basic rib scale  design. Something 
was working or several things were.  Do you see what  I'm saying?
  I'll crunch some numbers & see what I got.  I greatly  Appreciate the 
design sharing & information swap.
  Thanks
   Dale


It's  an entirely different system. Do a bearing load analysis 
on the ribs as  load carrying beams and see what the numbers 
say. They'll say that the rib  scale isn't adequate to support 
bearing without substantial panel  compression support.

Ron N

 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20060403/3b5e8abb/attachment.html