rib radius

[Delwin D Fandrich]

----- Original Message -----
From: <ReggaePass@AOL.COM>
To: <pianotech@ptg.org>
Sent: July 09, 2002 9:18 AM
Subject: rib radius


> Greg,
>
> Good question.  How about...all of them?  The piano in question is an old
> Steinway upright, 52" I believe, though I will double check that.  He is
also interested in opinions on downbearing.
>
> Many Thanks,
>
> Alan Eder

Hi Alan,

You're not going to get any consensus on this question. There are too many
variables -- not the least of which is your own background. How much
experience do you have making and installing soundboards? How much do you
understand about the process of forming and maintaining crown in piano
soundboards? Do you know the difference between compression-crowning and
rib-crowning? Are you comfortable with each process? Are you able to
evaluate the crown radius specifications someone gives you and relate it to
the moisture content of the panel you're installing at the moment of
installation? How much do you understand about moisture control? How much do
you understand about wood swelling and shrinking with changes in relative
humidity?

There are classes given regularly on the subject. Typically they take 3
hours to scratch the surface. I do all-day seminars on the subject, as do
others, and these only scratch the surface. (I'll be doing one of these, by
the
way, in So. Calif. on some Saturday late in October if I recall correctly.
Among the topics covered will be soundboard function, soundboard crown, rib
radii, etc.)

You can learn this stuff a number of ways. You can wade in and do it --
accepting the bad results with the good and learning along the way. Or you
can do your studying and learning from the mistakes of others first and
avoid at least some of your own. From experience I can tell you the first
way is both expensive and time consuming. When I went through the fire there
wasn't much alternative, these days there is.

I've written quite a bit on the subject, as has Chris Robinson, Nick
Gravagne and others. Some of this is good stuff. Check the Journal archives
or the CD-ROM. Check the reprint publication PTG has put together on the
subject. This subject has come up from time to time on pianotech as well,
you might check the archives though others will have to tell you how. There
is a wealth of information on the subject these days. Before starting work
on someone else's piano you really should spend enough time with it that
you're comfortable with what can go wrong with the job before it goes wrong.

Regards (and good luck!),

Del