"Oval or Round Shanks" or to bend or not to bend

[Delwin D Fandrich]

Richard Moody wrote:
> 
> OK.   So has anyone seen rectangular hammmer shanks?  Well my
> Chickering Anniversery Grand has 'em. I better measure,  they might
> be square.  Hmm wonder if I can get replacements?

Yes. Several companies have made them over the years. Most recently, I
think, Baldwin, though I don't know what they are doing now--I've not
looked at one in several years.


>         Also just to open another can of worms, what does "stiffness
> requirements of transferring the necessary energy to the hammer mass
> of each note"  mean?
>         The hammer can only do one thing as it approaches the string, and
> that is acheive a certain velocity. If Newton's (Sir Isaac) Laws are
> correct, full velocity is reached at the moment let off starts to
> occur.  The hammer is in acceleration to that point.  In the space
> past that point no acceleration can occur because the source of
> energy  has suddenly let off.  Since this let off occurs some
> distance from the string, the  hammer must then be decelerating, or
> loosing velocity as it strikes the string. Since let off is so close
> to the string the deceleration must be miniscual (sp? a word?) so we
> can envision the hammer velocity as the same at let off until
> striking the string.
>         But is this what is really happening?   Del suggests an idea by
> bringing up the "stiffness" factor in the shank.  Thus the hammer
> might be decelerating (or not accelerating as fast as the key is
> being pushed down) during the key blow because the shank is bending
> as a reaction to inertia. Because the hammer shank bends and  robs
> the  hammer of acceleration, this can be viewed as a waste of energy.
>  Perhaps the ideal shank would be one of ultimate stiffness, or one
> that doesn't bend at all.
>         On the other hand, a bent hammer shank may possess potential energy
> just as a bent bow ready to shoot the arrow.  So perhaps after let
> off, the bent shank tends to spring back and actually accelerates the
> hammer onto the string.  But maybe the paltry distance of 1/16 inch
> let off isn't enough for the bent shank to respond with its fullest
> energy potential.  Maybe a let off of say, 1/4 inch would give more
> space to allow more of this energy to be released.
>         Anyhow one can conclude that the let off of 1/16 (1.5mm) without
> considering hammer shank flex, is only concerned with the idea of
> most contact with the key to acheive the greatest velocity  of the
> hammer. In that construct, the hammer shank stiffness cannot be a
> criterion.
> 
>         Finally all of the above is mostly moot if we want to consider  the
> most important phenomena, what happens to the string during and after
> hammer contact?
> 
> Richard The Space Jockey
> 
> ----------


Most of what I have to say on this subject I've already said. See
"Action Power" Part 1 (August, 1996) and Part 2 (December, 1996)
published in the Piano Technicians Journal. May I respectfully refer the
reader to those articles?

If I can think of anything new to add to the discussion, I'll do so. But
for now, that's pretty much it.

--ddf