Rib Crowning Jig

[Farrell]

Ah yes, now I remember. Good to hear from you.

The main advantage to using laminated ribs is material uniformity/consistency. Obviously, wood is a natural product and each species has physical characteristics that fall into a range, but individual examples of the same species are going to have different strength (MOE) characteristics. Aside from general differences, such as grain orientation and density, unseen internal defects can drastically affect the physical properties of a solid rib.

Laminating the rib simply reduces the variation in physical properties found from rib to rib. I maintain a pretty tall stack of 3 to 5mm-thick laminations from a bunch of different boards. When I choose the laminations to build a rib slab, I purposely choose pieces of wood that appear to have originated from different boards. That way each rib I build is an average of all the boards the individual laminations were cut from - again, a more consistent and therefore predictable product.

Also, the process of cutting the thin laminations does a pretty good job of revealing any small defects in the wood. You'd be surprised at how many little knots and insect damage scars lurk inside small pieces of spruce - pieces often about the size of a piano soundboard rib!

Ever wonder why with two otherwise identical pianos, one has a collapsed soundboard and the other one works great? Obviously, some wood failed somewhere on one of the pianos and didn't on the other. Hidden defects in ribs can play a role in such failure.

That's a long-winded way to state: laminated ribs have more consistent and predictable physical properties than solid ribs.

I sell custom laminated ribs made to order. If you'd like to try a set of laminated ribs on a soundboard before tooling up to build them yourself, let me make you a set and you can get a feel for them first-hand - and then decide if you want to tool up.

I apologize for being hard to reach by phone - I know I can be lax with phone response. Email is always the best way to contact me. I'm pretty faithful about checking my email a couple times a day. I'd be happy to tell you what I can about Sitka (panels?)

Terry Farrell
Farrell Piano
www.farrellpiano.com
  ----- Original Message ----- 
  I try to call you several time but nobody has answered to me. ( about sitka)

  I meet you in occasion of the mitting with Del ... some month ago 
  and  just  I decided  to change system. 

  I still not decide what it's better, to cut the ribs whit router or to laminate them. (?????)

  Thanks again 

  Marco De Lellis
  Piano Workshop Inc.
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