Action Manufacturing & Alignment

[Delwin D Fandrich]

----- Original Message -----
From: "Farrell" <mfarrel2@tampabay.rr.com>
To: <pianotech@ptg.org>
Sent: June 24, 2001 9:45 AM
Subject: Action Manufacturing & Alignment


> I have a question (well, a bunch actually) about aligning action parts at
> the manufacturing stage. When a manufacturer builds a piano, how do they
> align the capstans/wippens/hammer flange-shank-hammer? The only way it
would
> make any sense to me is to stick the plate in the belly, string it, and
then
> take the keyframe, install the hammer & wippen rail (of course you have
> already designed the geometry of the action) and position hammers to be
> located under the string strike point (considering the arc they travel, of
> course) with shanks parallel to one another and perpendicular to the
hammer
> rail. Then you would install the wippens in a vertical plane with the
hammer
> shanks - and of course then they would be perpendicular to their rail.
Then
> you would cut your keys so that you could locate the capstans in that same
> planes of the hammer shanks & wippens. What you end up with here is an
> action that has is parts aligned. Or at least one that can be aligned. I
> realize various manufacturers are going to vary, but - Is this how they
make
> them? Is this how they should make them? How do they align all the parts?
Do
> they align all the parts? Do they align some of the parts?

You have the gist of it. In theory the manufacturer has the benefit of
having the whole system being designed to fit together. Working from a plan
(or master) drawing a keyframe is drawn to fit the available space, keys are
drawn in, action lines are drawn in, etc. The various drawings are sent to
those shops responsible for the various components--the top action, the
keys, the back action, etc. All of the various parts that make up the action
assembly. With a bit of luck as they all come together they will all fit and
slide into the cavity with a minimal amount of spacing. A keyframe rest
block is trimmed to width for the action to rest against with the hammers
all nicely aligned to the strings and the job is done.

Unfortunately over the years changes happen. Machines are re-aligned, minor
changes are made to scales or plates that don't filter through the system,
etc. I never did figure out why action stacks and keysets made in the same
factory for the same piano didn't align properly. What happens then is that
the workers on the line compensate. Sometimes they can even tell you when
things changed. But who listens to line workers? They don't get paid enough
to be smart, right? In any case, they have done this so many times they know
the hammershanks for this model have to go over here and for that model they
have to go over there and they just do it. Sure, it would be easier to make
all the parts fit properly, but the sad fact of life is they often don't.

-- Del