Del, I don't know if I buy that. Is the plate in or out? Regardless, my gut says it would take a very large force from the pipe clamp to measure a difference in crown. I think the sound board is constrained all the way around, but a force outward will not necessarily "suck" the crown out unless the force is HUGE (my gut feel only). I have an idea. Since you do soundboard replacement, I'd propose an experiment: 1. Take a soundboard has been crowned before installation, lay it on a flat surface and "somehow" measure the force/deflection rate. 2. Repeat the force/deflection measurement after the board is glued in (with the plate installed). 3. And since I have an outline of a soundboard for a FEA prediction for simply supported Vs constrained, I have no excuse. We can compare notes. What do ya think? Regards, doug richards San Jose, CA mailto:doug.richards@quantum.com > -----Original Message----- > From: Delwin D Fandrich [SMTP:pianobuilders@olynet.com] > Sent: Friday, December 04, 1998 6:36 PM > To: pianotech@ptg.org > Subject: Re: ribs and stuff (was alternatives.) > > > > Newton Hunt wrote: > > > Not if the end support moves. (soundboard end that is). > > Newton > > > > Ron Nossaman wrote: > > > > > Newton, > > > > > > The case has nothing to do with maintaining crown. The ribs maintain > the > > > crown, one way or another. > > ---------------------------------------------- > > Yup. Even then. You can demonstrate this for yourself by taking a pipe > clamp > -- the type that turns around so that you can exert force in an outward > direction -- and positioning it so that you can spread the rim apart. > This is > fairly easy to do on pianos using 'select hardwood' rims. Whatever crown > there > was originally in the soundboard stays there. > > Del
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