key levelling -- crown?

[Delwin D Fandrich]

----- Original Message -----
From: "Ron Nossaman" <RNossaman@KSCABLE.com>
To: <pianotech@ptg.org>
Sent: November 15, 2001 9:34 PM
Subject: Re: key levelling -- crown?


> >I'm surprised at you, Ron. Surely you've checked keybed crown in each of
> >those S&S pianos you've put new soundboards in. Haven't you? You haven't!
> >Why shame, shame, shame. How do you know the degradation you've been
> >blaming on the soundboard wasn't really the fault of the collapsed
keybed?
>
> Oh but I have, at least indirectly. I have without fail pounded every
> single crowned keybed that has ever passed across my threshold with my
fist
> and each and every one has emitted an appropriate "dunk" sound indicating
> to me that the keybed was entirely and adequately functional regardless of
> the presence or absence of such an arbitrary standard as measurable crown.

Pounding will give you only part of the information you need to properly
troubleshoot the possibly defective keybed. You will also need to carefully
measure its deflection under load, its exact crown and determine the
amplitude and frequency of any stray resonances that may exist. If they are
aliquot to any specific frequency of any of the vibrating strings the keybed
may be defective and in need of either serious repair or replacement.


>
> Performance under action load is, after all, what really counts here. I
> hear that some techs insist that if a piano in need of being rebuilt, the
> keybed is undoubtedly shot too and must also be replaced. I have not found
> this to be the case, and attitudes such as this disturb me greatly. The
> keybed is the soul of the instrument, and they not only don't deteriorate,
> but actually get better with age, like the keybeds in violins. Rare indeed
> is the piano in which the keybed is not at least as good as new,
regardless
> of age, and it's due time that this myth of keybed aging and deterioration
> is put to rest for all time.

I think you overestimate the structural integrity of the average keybed. Not
all of them are constructed of solid wood planks tenoned into slots cut in
the endblocks, the whole thing left to float freely so that warping and
distorting with changes in humidity is held to a minimum. You are probably
so used to working on only traditional instruments you are unaware of what
is being put into pianos by some unscrupulous pianomakers. Some keybed are
actually being constructed of thin sheets of wood laminated and bonded
together with some kind of adhesive that is so resistant to moisture that it
makes the whole assembly a homogenous mass that is so solid and stable they
are completely impervious to changes in humidity. It is these later types
that must be watched with particular care. They have only been used for 50
or 60 years and regardless of the environment they are exposed to they tend
to do absolutely nothing except sit there and support the action and
keyframe.


> I offer as evidence to this inarguable fact,
> my personal observation and lack of any body of documentation contrary to
> the effect that I know of no instance where the keybed of any piano has
> failed in it's primary application of keeping the action off of the floor.
> Consequently, I can only conclude that there are a number of unscrupulous
> practitioners of the piano rebuilding art who are perpetrating an
> outrageous fraud on their trusting and naive clientele by selling them
> wholly unnecessary and tragically destructive keybed replacements. I
> suppose that in some instances, it will become inescapably necessary to
> replace a keybed that has been maimed by an unfortunate accident or an
> inept attempt at repair of adjustment by an unqualified practitioner.

We only replace keybeds that have been shown to be defective due to
excessive stiffness. If the keys cannot be made to bounce properly when
pounded with the closed fist, the keybed is definately suspect. It may be
necessary to strike them with a large rubber mallet to determine whether the
keybed is at fault or if it is the broken keys that prevent them from
bouncing.


>
> In such instances, it is imperative that the oldest wood in the area be
> located, and procured by whatever means necessary to serve the higher good
> of restoring the defiled keybed to it's former and rightful glory. This
> won't, of course, be entirely possible, since the original designer,
patent
> holder, and builder of the original keybed was possessed of a supernatural
> knowledge and understanding to which we can never hope to aspire.

We only use wood cut from the center of the tree, this being--by
definition--the oldest part of the tree and, hence, the oldest wood
available.

I trust that in the future you will do extensive, documented tests and
record endless rows and columns of numbers to substantiate any conclusions
you may reach on the condition and function of the keybeds you test and/or
repair. That is the only way any of us will be able to tell if you know
anything about the subject and determine whether or not we should pay any
attention to anything you have to say about keybeds.

Regards,
Del