New board with cut-off for Steinway XR

[Ron Overs]

Hi all,

We're currently rebuilding an interesting little piano, a 1925 
Steinway XR grand (this piano has a model M plate) with an American 
Black Walnut art case and an Ampico reproducer.

Our brief from the owner was that he wanted it rebuilt to original 
spec, ie. without any modification bells and whistles, since the 
piano was in original condition when he purchased it. The board 
wasn't too good from a visual and tonal perspective so we decided to 
replace it.

The first plan was to build a compression crowned panel to keep it 
totally original. However, with only ten ribs and no bass corner 
cut-off, I decided that the board might be better made as a hybrid 
with crowned ribs and a moderately dried panel to 6%. So our purest 
ideals didn't last for long. I made a test soundboard strip of the 
longest rib (1200 mm) and found that it was very weak on account of 
the long span, with a quite high crown of 14 mm in the middle of the 
rib. For the sample, the rib-top was machined with a 60' radius. The 
dried test panel was glued to the rib with the rib-top-surface held 
at the same 60' radius. After panel re-hydration the test strip 
crowned a further 5.5 mm. This level of crown is likely to cause all 
sorts of packing problems with the rear aliquot blocks. Furthermore, 
I just don't like the middle-order ribs being so long and weak. So on 
Thursday night I took one of my laminated cut-off pieces and laid it 
in the case, just to have a look at possibilities. It made so much 
sense, and I can't see the point of re-boarding a case with an 
original design board which may fail in a decade or so on account of 
poor design.

So I called the owner in for a discussion. After explaining my 
thinking, he agreed that since we could cover the bass corner with 
the soundboard panel, thus hiding the evidence, and since the player 
gear will fully block visual access to the underside of the board, we 
decided to press ahead and fit one of my laminated cut-offs to the 
case. I'm still going to make the board as a hybrid supported unit, 
to keep something of the original design philosophy of the original 
maker intact. With the cut-off, the two longest ribs which were 1200 
mm long will now be around 850 long. This will be a much better 
result, since the middle-order ribs will be stiffer than those in the 
bass and the mid-board crown will now be much less on account of the 
shorter span, which will make the setup prior to stringing a lot 
simpler.

Here are some image links. I worked a bit over the weekend and got 
the cut-off fitted.

Here is an image of the cut-off with the rib notching machined before 
fitting it to the case.
http://members.optusnet.com.au/ronovers/steain.bd6.jpg

Here is the cut-of clamped in place with the ribs stock sitting in 
the notches for checking prior to gluing to cut-off in place.
http://members.optusnet.com.au/ronovers/steain.bd7.jpg
As you can see, the cut-off greatly improves the structural layout 
and soundboard-area distribution.

Here is an image of the cutoff glued and clamped into place.
http://members.optusnet.com.au/ronovers/steain.bd8.jpg
I was feeling a bit ho-hum about this piano with the original board 
concept, but now it will be very interesting to hear the end result.

Sorry I haven't contributed to any list discussion lately, since I've 
had a whole lot of other stuff to attend to.

Regards,
Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
_______________________

Web http://overspianos.com.au
mailto:ron at overspianos.com.au
_______________________
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