Chines and multi-piece rims

[Delwin D Fandrich]

----- Original Message -----
From: "Farrell" <mfarrel2@tampabay.rr.com>
To: <pianotech@ptg.org>
Sent: March 03, 2002 5:37 AM
Subject: Re: Chines and multi-piece rims


> My thoughts/questions are kinda running like Ed's here. How does a three
piece case allow improved geometry of the soundboard in the treble area
(allows you to start out parallel to the rear of the bridge at the treble
end from the get-go?)?
-----

The bend in the treble rim can only be made so tight. With the multi-part
rim I can put the chine anywhere I want it. And shape the bent side any way
I want.


>
>And how does it affect the bass end to better allow floating of the bass
end of the soundboard?
-----

Again, the bend of the continuous bent-laminate rim can only be made so
tight.


>
> Regarding Ed's questions about the massiveness and/or stiffness of the
rim, with solid timber sections of rim, is it not the case that all we would
need to do is increase size of these timbers and/or add framing until we
have whatever mass/stiffness we feel we need? We know how to join two pieces
of wood in a rather solid manner, so the fact that a rim is made of separate
sections should be of no disadvantage. Keep in mind that one full side of
all soundboards is a separate solid piece of timber - the belly rial (and
even those are often more than one piece) - although I must admit that I
have always assumed that this was the weakest part of the case.
-----

The belly rail is not actually a solid piece of timber, but a built-up
Z-shaped section with a number of inherent weaknesses. I've gone into their
weaknesses many times in my classes and I'll go into some solutions in my
Wednesday class in Chicago we discuss various aspects of pianobuilding in
the small shop. I'm not really prepared to write much about it just now.

Del