100+ Year-Old Laminated Rib

[Delwin D Fandrich]

I've run across these as well. The crown was cut into the rib rather than
pressed. Have you cut down the glueline to see what happens? My conclusion was
the same as Ron's -- they had a hard time bending the short ribs into a curve to
crown them so they basically cut them in half. 
 
They certainly knew about rib-crowned soundboards.
 
I haven't yet seen bent laminations in older pianos. It may well have happened,
I just haven't seen it.
 
Del


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From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of
Farrell
Sent: March 06, 2006 6:54 PM
To: Pianotech List
Subject: Re: 100+ Year-Old Laminated Rib


As a follow-up to my original post: The rib described below was 44 inches long.
I also ran across another rib from the same piano (while cleaning that unsightly
table) that was 25 inches long. That rib was similar thickness, but 33 mm wide
and its curve followed a 6 M radius. Amazing, IMHO.
 
Terry Farrell

----- Original Message ----- 
 
Just for the yahoo of it I planed the side of a rib that I had saved from an old
1890s Knabe upright that I tore apart. The rib had quite a curve to it (right at
7.5 meters radius) as you can see in the picture below by the straight-edge
placed next to it (please disregard the messy table, the belly and the tennies).
Most of the curve is in the center (the rib, not the belly), and the ends tend
to flatten out.
 
I wanted to see if I could tell whether it had just warped that way or whether
it had been cut that way. After planing to expose some raw wood I was surprised
to see that it was a laminated rib! Two laminations. The bottom lamination (away
from the panel) is of constant thickness. The top lamination in the picture
below (adjacent to panel) is about six millimeters thick in the middle (the
picture below is of the middle of the rib).
 
The top lamination in the picture below (adjacent to panel) is about six
millimeters thick in the center (see above) and tapers to nothing at the ends
(see below). The lower lamination (away from the panel) is about 13 millimeters
thick throughout its length except for the standard-type taper at the ends. The
rib is 31mm wide. The picture below is near the rib end at the taper.
 
Anyway, very interesting rib construction. I had never seen anything quite like
this. I have the original soundboard from an 1890s Knabe grand that I guess I'll
just have to yank a rib off of and take a closer look at it. Anyone ever seen
anything like this before?
 
Terry Farrell

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