Wooden action parts and frames

[Delwin D Fandrich]

Hi Phil,

I intended to respond to this way back when it was written but didn't get
around to it then. I hope you're still interested....

One of the early complaints I had with metal (aluminum) action rails was
what I perceived to be an increase in transmitted action noise. Now this is
not something I have done any real study on and don't have any numbers to
give you, but my perception was, back when I was doing a substantial amount
of field work, that actions converted directly from wood to aluminum tended
to sound somewhat noisier than their predecessors. This was most noticeable
during the transition period when pianos of same model would be side-by-side
one with wood action rails and another with aluminum action rails. The
brighter and harder the sound of the piano, of course, the more this noise
gets lost in the mix.

Piano actions in motion are inherently noisy devices. Lots of big and little
pieces flopping around and hitting each other. Even padded with felt and
leather they still generate a fair amount of noise. And the coup de grâce,
of course, when the relatively hard (sadly, more so these days than in the
past) hammer traveling at some velocity impacts the string set. Not only are
vibrations set up in the strings, a veritable cacophony of vibrations are
set up within the hammer and hammershank. Some of this is transmitted back
to the action rail, through the action brackets and keyframe, into the
keybed and, ultimately, into the air as sound. Our ears accept a certain
amount of this noise as normal--the piano is, after all, a percussion
instrument as well as a stringed instrument. An excessive amount becomes an
annoyance, though it appears to be an annoyance we can get used to. Or one
that we can bury if we just make the rest of the noise generated by the
piano loud enough and hard enough.

I doubt that your Bechstein representative intended to imply that certain
vibrations were essential, or desirable, to the overall sound mix, but that
they were not. Much gets lost in the translation between languages. Wood
tends to dampen at least some of the higher frequency vibrations inherent in
the piano action function, aluminum tends to transmit them freely. The
Kranich & Bach unified action frame casting (that is, the keyframe center
rail, back rail, action brackets and both main action rails were all cast as
a single unit out of gray iron) dampened them quit nicely. Nearly thirty
years after removing that action to my shop for repairs and regulation, my
back has still not completely forgiven me--but it was a quiet action. Other
quiet actions of my acquaintance have been found in certain early actions
having wooden action rails and wooden action brackets. I once encountered an
action key frame resting on three strips of felt--one each for the front,
center and back rail nicely set into a machined recess. I don't recall
knowing enough about piano function at the time to properly evaluate the
system in terms of action efficiency, but it was a quiet action.

Stability in both wood action frames and rails can easily be achieved by
making them out of cross-laminated veneers. Of course, this also reduces
their vibration-damping characteristic and increases their vibration
transmission efficiency. Life's a compromise. The Decker piano I am
remanufacturing for myself has, and will retain, nicely crafted three-ply
cross-laminated maple action brackets. The only change is that they are now
epoxy saturated for stability and to insure their long-term structural
integrity. After all, they are nearly 120 years old--someday they may
develop structural problems.

Del


----- Original Message -----
From: "Phillip Ford" <fordpiano@earthlink.net>
To: <pianotech@ptg.org>
Sent: December 15, 2002 1:14 PM
Subject: Wooden action parts


> A few additional words on the teflon flange and bushing thread that I
decided
> to put in a separate post.  My own feeling is that any non-moving part of
the
> action would be better made of stable material (not affected by
temperature or
> humidity).  This rules out wood.  The parts in question:  keyframe,
brackets,
> rails, and flanges.  Brackets are universally of metal now, I believe.
Rails
> often are.  Why not the keyframe and flanges?  Any reasons to make them of
> wood?  Any pianos out there with these parts non-wood?
> I had a conversation a few years ago with someone from Bechstein.  I
> mentioned this to him and he said something to the effect that when the
hammer
> hits the string vibrations travel through the action parts, rails, etc. to
the
> key.  Therefore these parts need to be wood to transfer the 'proper'
> vibrations.  Any thoughts on this?  I agree that it's important to feel
the
> piano's vibrations in the keys as you're playing.  I had always assumed
that
> this was coming through the keybed and keyframe to the key, and not back
> through the action from the hammer.  Regardless, I can't see that having
metal
> in the path rather than wood would damp these vibrations.  It probably
would
> damp them less.  This could result in a different feeling at the key,
which
> might be better or worse.  It seems something that could be established by
a
> manufacturer fairly easily.  Has any manufacturer experimented with this?
>
> Phil F
>
>
>
> Phillip Ford
> Piano Service & Restoration
> 1777 Yosemite Ave - 215
> San Francisco, CA  94124
> _______________________________________________
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