Plate Substitution

[Ron Nossaman]

>Yesterday I examined a 9' Baldwin Concert Grand circa 1936 that was
>partially rebuilt six to eight years ago. The history related to me by
>the owner was that the original plate was broken somehow and the
>rebuilder substituted a new SD-10 plate. I could find no modifications
>in the bridges or anywhere else for that matter.

Hi Paul,
Sounds suspect. Did it have vertical hitch pins? The 1936 plate wouldn't, 
but an eight year old replacement would.


>The complaint from the owners is that the instrument will not stay in
>tune even for a few days.
>
>The piano got a new pinblock but the block/plate flange fit is not the
>best. There are areas of solid contact all along the flange length,
>separated by areas where there are considerable gaps. Not good.

Not good, but not necessarily the problem. Is it tuned by someone who knows 
what they're doing? How does it go out of tune - unisons, low tenor, killer 
octave, high treble??? Is the piano sitting in direct sun, or have a nearby 
heat register blowing hot air on it?


>The piano did not get a new soundboard or bridges(lots and lots of
>hairline cracks) and there are a number of repaired cracks and some new
>ones as well in the SB.
>There is down bearing on the bridges but I did not check the crown,
>although I am skeptical about that.

Me too. A collapsed board with a lovely S shaped crown will be very 
unstable. This is sounding very familiar. Rebuilders who don't replace 
soundboards typically just lower the plate to get some measurable bearing 
and don't even consider crown. I'd suggest checking crown with a thread 
(Kansas straightedge) and flashlight. Check everywhere you can reach, not 
just the longest rib, to get a reasonably clear picture of the board's 
condition.


>There is also what appears to be a separation in the rim in the bentside
>curve. I don't think this is a factor in the instability.

Probably not.


>Clearly, this piano needs a new soundboard, bridges and a new pinblock
>but I'm wondering to what extent the plate substitution is evolved.

I don't see anything here that would make the plate the culprit, but I'd 
expect a new board, block, bridges, fixing that rim separation and getting 
everything back to where it belongs will help. I still suspect 
environmental reasons for the tuning instability too.

Ron N