Inertia and Action Parts

[Dennis Johnson]

       We all have a lot to say about this topic because it comes very
close to the source of a lot of our action problems, and there have been
some very useful comments about inertia, leverage, acceleration and parts.
I believe that in general we, at least on this list, are in agreement
concerning these issues and their critical relationship to how responsive
the particular piano action will be in the end.  But to be sure, as Bill
Spurlock put it, there are always ten (or more) technicians ready to point
out how they would have done it differently.
        I dare to suggest however, that when it comes to action parts I
think that we may have some disagreement.  A few here have mentioned that
they generally "stick to the post-1984 parts" or advise to "stay away from
those pre-1984 shanks", and I have frequently seen this attitude elsewhere
as well.  With respect to your rights to favor one dimension over the
other, I argue that you are missing the opportunity to offer greater
possibilities to your faculty and customers.  I DO NOT use the pre-1984
shanks from Steinway with the large knuckles, of course, but Renner's c.
1911 dimension shank (with the small knuckle) and their Hamburg dimension
shank (with the large knuckle) offer radically different possibilities. We
all know that the Hamburg offers greater leverage and can handle a heavier
hammer, if that is what you or the player likes.  This is what Ken referred
to when he said, " The mechanical advantage gained makes for actions that
will appeal to a broader spectrum of players".  If you stick with the
heavier Steinway hammers that is certainly true, but the Renner c.1911
shank with the small knuckle offers a significantly quicker repetition.
These c.1911 parts, when used in combination with an appropriately light
hammer can perform the same touch weight specs. as the Hamburg, but it
requires some radical weight reduction.  I routinely taper the sides of my
hammers to about .3" above the shank at the base of the felt, and also thin
all my shanks to about .185".
        None of this is new information, and there is definitely a
different "feel" between these actions with more or less leverage, even
when the touch weight is practically the same.  I have found that the extra
time spent reducing weight for that early dimension is usually balanced by
the extra time spent solving regulation problems fitting the Hamburg parts
into N.Y. pianos.  Perhaps the most common regulation problem that I find
is adjusting the height of the rear action brackets to the key frame.  I
have not yet figured out a better way to set this height other than trial
and error.  (Up to set shanks closer to the rest rail or cushion, down for
greater clearance).  I have also cheated on the blow distance a little with
the Hamburg action to reduce key dip and enhance repetition slightly.
        I offer both dimension actions in our hall, where we have three
Steinway D's.  Two have the Hamburg action with N.Y. hammers and one has
the c. 1911 with Renner Blues.  They are all nice, and the players are
divided as to which they prefer, but I confess that am a little partial to
the later.  Sometimes with customers it is very difficult to determine
which is the best choice because I like to inform them and even involve
them in such critical decisions, but this is just to much for most to
grasp.  Many times you just have to make an educated judgement based on
your knowledge of the player, but whenever possible it really helps to have
them come and play the two different actions.

        I may have drifted into another topic, but this is something that I
was meaning to bring up soon anyway, and it might as well be now.


Dennis Johnson
St. Olaf College
johnsond@stolaf.edu