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MMD > Archives > September 1997 > 1997.09.19 > 16Prev  Next

Ampico B Tracking Mechanism
By Craig Brougher

At the expense of not seeming to be appropriately grateful for Robbie's
agreement with me about the Ampico B tracking mechanism as a roll
shredder, I want to say that I have always felt that the model B tracker
is the best overall when detailed, that I have ever found! It is also the
most sublime in its design and balance.  So it is difficult to fully
understand and adjust.

I have an Ampico B, and use it to play the worst dog-eared, curled,
feathered, ripped up rolls I have, knowing that my piano will eventually
straighten them all out and I will be able to play them better as time
goes on.  I can track the wildest roll on that piano with ease, now!
But years ago, it took a lot of work to study out the mechanism.

I had a lot of confidence in the wisdom of Dr. Hickman, having met him
for the first time in Philadelphia.  I knew, by listening to the man that
he was exceptional and detailed beyond anyone I had ever met.  He was
also doggedly determined, and his mind was working on his problems, even
in his sleep -- I suspect.  That's the kind of guy that doesn't make
assumptions and doesn't make mistakes because he was far more critical
of himself than his worst critics, and very appreciative of others'
abilities conversely.  So I trusted him to give me a basically
well-designed tracker.  I was not disappointed.

The only real problem with the Ampico B tracking system was the strength
of the flat springs.  Both are bending when the roll touches either
finger, so what you have to do is counterbalance that force at the
opposite tip end of each finger, behind the cover panel under the
trackerbar, with home-made compass springs.  Then you have to balance
the very tiny force left to be about equal, so it doesn't favor one side
over the other.  Now you end up with a tracker finger that you can
actually deflect by blowing on it!

By putting a wave washer under the head of each screw holding the finger
assembly, you are able to adjust the finger spread very precisely and
minutely to center them on the trackerbar and spacing them so that the
total travel of the poppet wire is about 1/32-inch.  That final distance
and centering can be adjusted while a roll is playing, then the screws
are tightened up.  The poppet travel is also adjusted optimally, and
finally, you will get a powerful, prompt action of the tracker with every
tiny side movement of the roll.

It is also necessary to know how to set up the linkages to the roll
chuck, and to get all friction and dragging of the yoke lever off the
left roll chuck shaft.  The alignment of the center position of the
pneumatics with the centering of the roll is done at the end of the long
linkage rod which has a thread, and is adjusted from the end of the
drawer through an access hole.  (The threaded bushing it adjusts is
split and must first be unclamped.)

There are also adjustments you must make, like proper spacers, etc.,
that have to sometimes be added, once the drawer is reassembled, because
tolerances have changed.  Don't forget that your tracking pneumatics have
to start out cartridge tight before you ever begin.  If you have slightly
porous cloth, forget it.

I just want everyone to know that properly set up, the Ampico model B
tracker is my ideal of a perfect tracking mechanism, given a few extra
"adjustments," and a special regulation, that includes playing a large
variety of rolls through and keeping an eye out for tendencies to "lean"
left or right very very slightly!  Had Dr. Hickman another year, to
develop it, he would have fixed its finger pressure problem.  Nothing
escaped that guy!

Craig Brougher

 [ Thanks, Craig, you present a very convincing case -- I'll try your
 [ suggestions!   -- Robbie

(Message sent Fri 19 Sep 1997, 16:00:07 GMT, from time zone GMT.)

Key Words in Subject:  Ampico, B, Mechanism, Tracking

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