Even balance weight or even something else, that's thequestion.

[Bill Ballard]

At 10:16 PM -0700 4/21/03, David Love wrote:
>  I don't really know how to handle the inertia question in a
>quantifiable way--not yet anyway.  There are those who are working on the
>project, though, and it will be interesting to see what comes of it.

If you are referring to Stephen Birkett (as you did in the original 
post), I'll let him speak for himself. Yes, he will produce the 
Mother of All dynamic grand action mathematical models. No, he didn't 
the Guild  Foundation funding he'd been asking for five years ago, 
and the actual source of the funding will be the beneficiary of his 
work. What I know he told me in a private email, but I don't think 
I'm abusing his confidence.

>I am reminded, however, of a presentation I saw some years ago by Rich
>Baldassin.  In short, he had a customer who complained of an action that
>was too light.  Taking lead out of the keys did not seem to solve the
>problem adequately.  Anyway, to make a long story short, he found that in
>order to satisfy the customer, what was needed was to add two leads, one
>behind the balance rail and one in front, equidistant from the center.  The
>net effect on the balance weight would have been zero, but the, presumably,
>increase in inertia was what the pianist was looking for.

I'd like to step back from your story and Rick Baldassin's, to 
reflect on how the three forces at work in an action, friction, 
gravity and inertia, have moved from dimly suspected, to regulated to 
specific targets, to (finally) ingredients in a soup which can be 
balanced to the taste of the chef (for a particular customer.

Friction of course, is the "parking break" of the action, slowing the 
action down whether you're in forward or reverse gear. Gravity (BW) 
acts like a spring in that whatever the net balance of gravity 
between the two halves of the key, the force which the pianist 
applies in overcoming it on the downstroke is not lost but stored for 
the key's return. (Well, not completely like a spring which requires 
increasing force as you continue to deform it.) Inertia is only felt 
when the action parts change speed (ever heard of them changing 
direction, that is from their plane of rotation?). But Inertia is the 
toll-booth at the outset of play (and to a minor extent, a "use-tax" 
applied to any increase in speed that the pianist during the 
downstroke). All three forces of course are there at the outset, but 
as soon as the pianist gets the parts moving, inertia has been paid 
off. Mind you, as the other two forces exert their constant tax on 
the motion of parts, the pianist with find more acceleration 
required, simply to maintain level speed. Thus, the size of the other 
two forces will bring inertia back into play. But this is nothing 
compared to the amount of inertia encountered at the very beginning.

In fact, I've always thought of inertia as a vanishing brick wall. 
When the pianist's finger strikes the key, its own velocity 
(considerable) goes smack into the dead zero velocity of the key and 
the parts loaded on it. There is a momentary squashing of the finger 
as the key picks up speed, but as soon as the two match, inertial 
resistance disappears. Starts out as a brick wall, and after a few 
miliseconds, it's gone. Which is not to say that the energy poured 
into the parts to overcome inertia is lost. Like the energy to 
overcome gravity, it is simply stored temporarily in the parts.

Fifteen years ago, action friction was a matter of a long list of 
preparatory steps, which when executed would put a Good Housekeeping 
Seal of Approval on the action. One or two people had suggestion that 
it could be inferred from Down and Up Weight, but they were few and 
far between in a world of techs for whom action resistance was DW and 
nothing more. Since then, it's been possible to determine whether 
friction is a matter simply of good housekeeping or instead, heavy 
hammers. Also David Stanwood's friction control shanks have allowed 
quick exploration of different levels of friction on the action and 
the pianist. The same thing can be said for his adjustable helper 
spring, in experiencing different levels of BW. If you buy David's 
assertion that  FW is a good measurement (albeit static) of inertia 
(and I do), we're now at the point where all three can be set to 
specs, and two out of three can be reset on the fly. Fifteen years 
ago, we didn't have that. Now we do. It's a brave new world.

But just to keep things sober and in perspective, all of this 
pertains to the mechanical aspect of the action's "feel". It doesn't 
directly accomplish anything for the sound of the piano, which is 
where the art and the gift in our business lies. Confusing the issue 
here is that fact that when pianists report that an action feels 
good, they mean that getting the sound they want out of the piano is 
easy. They don't have to hunt for the sound they don't have to 
struggle to draw it out. The set-up of the action may contribute to 
the sound mainly in the absence of work done wrong, but for the most 
part the sound comes from the condition of the hammers and the belly. 
That's another ballpark entirely.

Bill Ballard RPT
NH Chapter, P.T.G.

"Talking about music is like dancing about architecture"
     ...........Steve Martin
+++++++++++++++++++++