Piano Rims (rambling post)

[Delwin D Fandrich]

----- Original Message -----
From: "Phillip L Ford" <fordpiano@lycos.com>
To: <pianotech@ptg.org>
Sent: December 30, 2001 6:34 AM
Subject: Re: Piano Rims (rambling post)


>
> Do you think it [the bellybracing] needs to be wood?  Why do you think
> many makers settled on softwoods for the braces?
> I noticed that the Walter grand has maple braces.
> I've seen a piano with a cast iron bracing system
> that was bolted to the inner rim.  Do you think
> there would be a disadvantage to metal?

The Walter grand uses maple bracing because that is what I used and
specified when I built the prototype. They liked the idea and have continued
using maple. They are in an area where they are able to get ongoing supplies
of good maple. Lucky them.

I'm not convinced bellybraces have to be maple, we are using something else
in our
own piano. Probably spruce. Maybe alder.


>
> >The function of the cast gray iron bell used in
> >the larger S&S pianos could probably be better served by a bellybrace
> >extending from the inside curve of the inner rim to the bellyrail. A
> >nosebolt could still be used to mass couple the plate to the brace.
> >Nothing would be lost and much would be gained.
>
> Do you think that the bell puts any rolling preload
> on the rim or resists the rolling or twisting of the
> rim caused by soundboard vibration any more
> effectively than a rim brace would?

No. I don't think the bell is as effective as a well-placed bellybrace would
be. Or is.


>
> Also, slightly off the subject, but do you think a
> heavier plate in this area or a rib on top of the
> plate could as effectively do the same thing as the
> nosebolt?

I don't think so, but I've not tried it. Nor am I going to. I'm trying to
get excessive mass out of the piano, not putting it in. If a well-placed
(and relatively light weight) wood brace is effective, I'm not going to add
more iron.


>
> If what you want is the entire soundboard moving up
> and down as a diaphragm it seems to me that having
> this hinged edge attachment might come closer to
> giving that than a clamped edge arrangement.
> Actually building something workable might be
> difficult.

And we must avoid difficulties at all cost!

As time goes on I find myself coming closer and closer to the notion of a
hinged-edge diaphragm configuration. Our soundboards are functionally very
near that now. And my new 200 cm grand design is even closer.

Del