Thoughts on soundboards...you out there Ron?

btrout@desupernet.net btrout@desupernet.net
Thu, 18 Mar 1999 20:07:19 -0500


Hi Ron,

Thanks for the input.  Someday, maybe it'll all 'click' together in my mind,
sort of like the pieces of a jigsaw puzzle coming together!  I found some of the
articles in the Journal, and I'm going to see if the library can get me a few
books that Del recommended.

Fit the pinblock to the plate flange today, (amongst other things).  I finally
figured out that if I make that thing first, and get it all fit up, and lined
up,  it's a lot easier to put it all together After the plate is all finished,
without putting scratches and dings in the fresh finish.

I'm curious, how do you fit your pinblocks?  I use a graphite and alcohol
'slurry', paint the flange with it, put the rough pinblock in place, hammer on
it a little, and take down the high spots with a rotary rasp in the drill,
repeating until I have nice coverage over the entire pinblock (that's the
general jist of it...).  I got to make a new pinblock for a fairly new Baldwin
last year (water damage) and there was some kind of 'shmutz' in there between
the flange and the pinblock.  Do you know what they're using?  I've wondered
about it.  It seems to be pretty tough stuff, and it seems like it would take a
lot less time...

Anyway, thanks again.  I appreciate the good thoughts!

Best wishes, always,

Brian Trout
Quarryville, Pa.

Ron Nossaman wrote:

> At 07:30 AM 3/18/99 -0500, you wrote:
> >Hi,
> >
> >I had the opportunity to dismantle an old 1915 Baldwin "E" (5'8") over
> >the last couple of days that I'll be rebuilding. Looks like it'll be a
> >Nice piano!
> >
> >I've been reading a little on soundboards, and from what I've read so
> >far, most soundboards are too rigid in the bass, and not rigid enough in
> >the treble.  (Over generalized, I know, but it's a start?)
>
> * Hi Brian, sounds, generally, like a pretty good start to me.
>
> >On this
> >Baldwin, I noticed that the lower half (aprox.) of the long bridge was
> >notched out on the bottom so that it only touched the soundboard by way
> >of about 4 inch and a half squares of what would be the bridge body
> >spaced evenly along the bottom of the long bridge.  I was thinking that
> >maybe that was to encourage the soundboard in that end of the piano to
> >vibrate more freely.?
>
> * I think that was the idea, though I'm not sure why they would think that.
> Most of the diaphragm action of a soundboard is along the ribs, not the
> bridge, though bridge weight and stiffness is a factor. I wouldn't think
> there would be much action between the ribs, along the bridge line, and
> parallel to the panel grain, that the notches would help.
>
> >I haven't taken notice of the bottom side of the soundboard yet, but I
> >wondered if my thinking is on the wrong track to think that perhaps (in
> >general), if the soundboard is not rigid enough in the upper end, that
> >either an extra rib or two, or adding to the thickness of the ribs might
> >accomplish this stiffening effect?
>
> * That's the basic idea. Consider a rib a center loaded beam. The stiffness
> and mass of the rib/panel/bridge assembly is what controls impedance in
> different parts of the board. The idea is to keep the mass relatively low,
> and control the stiffness with the panel thickness and rib configuration.
> Since beam stiffness increases directly with the width, and with the cube of
> the height, you can make a rib stiffer, without increasing it's mass, by
> making it taller and narrower. Make sure you have bottom brace clearance.
> Crown the ribs, instead of relying on panel expansion to supply crown to
> flat ribs, and you gain a lot more control of the result, and a longer lived
> soundboard.
>
> >I know I'm rambling a bit, but if anyone has a thought they'd like to
> >pass along, I'm interested.  (Ron, I know you're light years ahead of me
> >on this, so that's why I thought of you in particular.)
> >
> >Hope you all have a great day!
> >
> >Brian Trout
> >Quarryville, Pa.
> >
>
> * It's all Del's fault. <G> He got me interested in this stuff, and I'm
> trying to catch up. It truly does work, and there are plenty of things to
> learn yet.
>
>  Ron





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