Laminated ribs and grain angle

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: Farrell=20
  To: Pianotech=20
  Sent: November 12, 2003 3:04 AM
  Subject: Re: Laminated ribs and grain angle


  And this leads me to a concept I have never been at peace with: panel =
flitch width. Seems that a popular target flitch width is maybe about =
four inches. I have trouble imagining how a number of narrow flitches =
would be detrimental to the soundboard. That would allow use of some of =
this non-optimal-grain-angle wood by resawing to quarter it. Now =
certainly more work would be involved, but I see that as the only =
downside. Some may suggest appearance, but I don't see that as an issue =
- often the only way I can find flitch joints on a subpanel is to look =
for the squared-off ends - straight grain and consistent color make =
joints nearly invisible. Is there something else I need to get a grip of =
to understand this?

Ah, but Terry, appearance is the issue. That and a lot of mysticism. =
Most of the mythology we have accumulated about soundboard construction =
goes back to the erratic and unpredictable nature of the =
compression-crowned soundboard structure. And with this construction it =
is important to remove every possible variable. When a panel doesn't =
belly "properly" or if the piano ends up not sounding quite right -- not =
quite "great" -- it must be because the grain was too wide. Or too =
narrow. Or because the boards were too narrow. Or too wide. Or the wrong =
color. Or because it came from the south side of the mountain. Or the =
wrong elevation. Or the grain angle was slightly off perpendicular. Or =
something. Perhaps it's just one of those mysteries of life that is =
beyond our comprehension -- "we don't know why some pianos come out =
sounding great and others don't." It's a mystery.

These factors become less critical the further you get from the pure =
compression-crowned system.=20

  FWIW, I most often use 45-degree grain-angle (non-nicely quartered) =
spruce for rib laminations. I reverse the grain angles from lamination =
to lamination like below, thinking this may maximize stability. Don't =
know this really does anything except make me feel better - but it most =
certainly does do that (please don't burst my bubble).

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  Terry Farrell
Whatever makes you feel good, Terry. Go for it. In reality, though, when =
the thickness of the laminations becomes small enough it doesn't seem to =
matter either way.

Del
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