Laminated panels (Farrell)

[Richard Brekne]

Hi you two.

The decision was made because I wanted to keep as much as I could as 
close to the original panel design as I could make it...except a couple 
very specific things. I wanted to see the result, lacking enough 
engineering expertise to foresee more then minimal issues. The middle 
lamination offset of 20 degrees to the outside two was Del's suggestion, 
which was his only contribution really... I dont want to <<blame>> him 
for anything here.  I kept the outside two in the same direction because 
I wanted the bass / low tenor area of the soundboard to be essentially 
the same as the original one... while the treble area was to be affected 
by the inside laminate that was used to form crown and provide a degree 
of crown support. The idea was to get the treble to behave more like a 
modern piano and the leave the bass and middle area of the piano pretty 
much like it was originally designed. The only other change was to 
lengthen the scale on the long bridge  a bit to accommodate pure sound  
wire and a slight raise in tension... particularly in the high treble.

I believe.. but do not know... that I probably should have asked Terry 
to dry the panel out a bit more then he did before ribbing. Tho the ribs 
were slightly crowned the end result... with that floating chunck of 
mass on the right side of the tail.... resulted in a sound lacking in 
lower frequency response.  Stiffening rib number 1 right under the 
intersection with the long bridge changed that completely and now there 
is that very familiar kind of bass sound found in these instruments... 
and a very gradual transistion to a more modern sounding treble.  So the 
experiment was a success really.  I'll do better next time around for sure.

We DID think about bringing in a designer but I had a couple specific 
goals I wanted to accomplish... which I did.  I'd be delighted at this 
point to sit back and listen to designers pick apart this thing..... I 
can provide the scale and downbearing figures if desired.

Cheers
RicB

         >Wouldn't having the bottom lam 90 to the above lam hold a
        radius better. Like a rib. Why have them close to parallel?


    In this particular case, I'm not sure why Richard Brekne chose to
    keep them close to parallel. Likely to keep as much stiffness up
    there as is possible. As far as laminating some crown in the panel,
    I suspect you are correct that a 90 lam would make things bend
    easier and have less relaxation with only three laminations. But we
    were able to place the desired amount of crown in it and I suppose
    it will make it more stiff.

    We should probably ask a designer 'bout this stuff!   ;-)

    Terry Farrell