Blows to Tuning Stability

[Yardbird47@aol.com]

(expletive delete) what a conversation we've got going on test blows. My
feeling is that if all the folks who say they never pound a piano were
separated into the ones delivering an actual mezzo-blow (maybe 10%) and those
with a forte blow (the complementary 90%), and if all the tooners who say
that a piano has to have its last ounce of instability beaten out of it were
separated into those who actually break keys and strings during a tuning and
those who don't (as before, respectively, 10% and 90%), THEN if we got the
90% of all those in either group together for a show and tell of tuning
techniques, that we'd find our test blows pretty similar. How we describe our
test blow might be a function of whether we vote with the "tough-love"
law'n'order gang, or with the pinko-liberals! Whether a strong test blow
reduces or induces tuning instability appears to still be no more than
opinions (Dave Porritt, 12/30 and his reference to Ben McKlveen, and Dale
Probst 12/31)  I split the piano work at the Marlboro Music Festival this
summer (20+ factory-fresh Steinways) with a guy who I know has a lighter
touch than myself. Both of us were on all pianos, and I couldn't tell any
difference between what he'd tuned last week and what was mine.
Tuning stability is a much bigger subject than just test blows. Alot of it
has to do with the balance between tuning pin friction and string friction.
Richard Anderson is working on this right now in the Journal, but with a
slightly different assumption from my idea in 2-3/91. His idea is that
friction differentials across bearing points (say the front duplex) are
continually relieving themselves, with wire creeping across regardless of the
size of the friction barrier. Presumably this relentless self-leveling is
accelerated by the string's intermittent jerk and wiggle (initial
displacement and subsequent waveform). I still do think (and will until some
engineer steps forward with actual experimental results) that the friction
barriers will hold these tension differentials steady until a change occurs
on either side (say with our hand on the tuning hammer, or a good slug from a
strong player) to overcome the friction barrier.

Richard West writes 12/31 <<Four or five, quick, light to moderate test blows
will test stability better than one or two hard strikes. And too hard a blow
will destabilize the string so that on soft blows the pitch will rise.>> Is
this anecdotal?, is there a mechanical theory accompanying this?

Dave Porritt writes, 12/30 <<In most pianos you can feel if you have
stability in the feedback from the tuning hammer. When you feel that there
might be some unequal tension in the string segments THEN you bang.
 Otherwise if you don't feel that from the hammer a moderate blow is
sufficient.>> What information is your tuning hammer feeding back to you? The
only thing it really tells me about directly, is torsion in the tuning pin.
Or am I being too literal? In my experience, the sense of whether instability
remains comes from a murky correlation between the amount of wire I feel
moving at the tuning pin and what I hearing changing in the speaking length.
In discussing the subject, any generalizations of my would have to specify
(how's that for an oxymoron!) the relationship between string and pin
friction, whether it was a piano hideously warped from last summer's tuning
or very close to last week's tuning. And while we're specifying things, is the
 bad unison we're talking about of the Bronx Cheer sort, or is it on the
order of a winking of a gnat's eyelash, say a 9th partial beating @ .5 bps?
Going back to the big show&tell session  earlier mentioned, I believe we can
all come by our tunings the day after and find the gnat winking at us.

I thank Richard and Dave for their ideas, and if they feel singled out in
this ramble of mine they shouldn't worry. I look forward to any and all ideas
on tuning stability, and will be equally quick to probe anyone else whose
idea isn't accompanied by a mechanical theory. We're all in this together.

Bill Ballard RPT
Putney, VT