Laminated panels (Farrell)

[Farrell]

>Why would this be a factor? 

No, it's got nothing to do with dimensional changes, but rather the rate of glue cure. My understanding (minimal as it is) is that if the wood is too dry it will attract/draw the water out of the glue before it can dry in its proper manner and thus create a weak glue joint - it weakens the glue if the water is extracted too quickly.

>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

  ----- Original Message ----- 
  From: Fenton Murray 
  To: Pianotech List 
  Sent: Wednesday, January 30, 2008 9:58 AM
  Subject: Re: Laminated panels (Farrell)


  So I have often wondered about how drying the panel (and ribs????) down to 3.5% MC prior to rib gluing might affect the integrity of that rib-to-panel glue joint when using a water-based glue (hot hide, Titebond, Bolduc, etc.). That's another reason I find more comfort in gluing ribs on at 6 or 6.5% MC (and not drying ribs).

  >Why would this be a factor? Because of concern over a dimensional change in wood after glue up, why would water based be a factor. When the wood takes on ambient moisture it attacks the glue?  Can't be. I don't get it. I never heard that. Wood can be damaged by over drying, but if it is controlled and slowly brought down, that's different. Of course the opposite is true, it can't be good to take out a 3.5 panel where I live (66% average ) and let it freak out in a piano glue up.

   With the panel laminations nearly parallel, it was pretty much like incorporating a rib directly into the panel.

  >Wouldn't having the bottom lam 90 to the above lam hold a radius better. Like a rib. Why have them close to parallel? I see what's happening at the tail. At first I thought is was an added panel.

  Come on down! We'll mix up a pitcher of margaritas and talk piano belly.......

  >I've got a good piano belly.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20080130/34710a4b/attachment.html