[pianotech] Pitch change, etc.

[Ron Nossaman]

Scott Nelson wrote:
  > What was interesting was under favorable lighting 
conditions, you could
> see the horizontal lams statring to split apart and lift at many of the 
> bridge pins, almost as if the pins were leveraging the cap apart where 
> it was weak. I used to think that the laminated structure would be 
> stronger, but apparently the material was yielding in this case.

Laminated stuff is prone to that. It's not that difficult to 
damage the top lamination. The advantage is that the damage 
doesn't propagate further into the structure, like it will 
with solid wood. The more impregnated the layers are with 
glue, the less prone to damage the outer layer is. An example 
is Baltic Birch plywood. It's wonderful stuff, hard and 
stable, terrific to work with. But it's not held together with 
a lot of glue, and the face veneers chip and splinter easily.


> Could this be an example of the Delignit bridge capping material you 
> were referring to? 

No. The Delignit stuff is 90° cross plied, and very stripy 
looking. Those laminated caps in the new pianos look to me to 
be a parallel, or near parallel, lamination. I don't know if 
they're making it themselves, or if there is a supplier out 
there in the world somewhere that makes it for them. I know 
the Permali folks will make high density low angle laminates 
from Beech, but the stuff I've seen in pianos looks more like 
maple.


>If so, it would seem that your use of veneer or 
> thinner plies with epoxy saturation would indeed be more structurally sound.

It seems to be, which was the plan.
Ron N