In the 160524 MMD David Sharpe mentions having issues with his
Duo-Art not tracking properly during play.  A number of individuals
have responded with excellent suggestions for setting the tracker
system to specification.  One issue which I have not seen addressed
is the importance of the alignment between the roll spindles, the
take-up spool and the tracker bar.

The grand Duo-Art spoolbox has about the most severe angle (relative
to the spools and the paper travelling over the tracker bar) of any
player system I know of.  (Well, maybe the little Tom Thumb Recordo
midget uprights are severe, and for the same reason: there is limited
space available to house the spoolbox.)

Until late 1924 the spoolbox on the grand Duo-Art was mounted on the
keyframe of the piano, so the spoolbox will shift to the right whenever
the soft pedal "una corda" is employed.  This was changed post-1925
after which time the spoolbox was attached to the "stretcher" of the
piano, with two "L" shaped brackets and four screws plus an alignment
pin on either side.  This later arrangement (employed until end of
production) provided a much sturdier mounting of the spoolbox, retaining
the all-important alignment between the spools and the tracker bar.

What I am suggesting is happening in Mr. Sharpe's Duo-Art is that
alignment of the spools is off by some measure due to a "twisting"
of the spoolbox.  There are (in most cases) only three mounting studs
which secure the spoolbox to the keyframe.  There are brackets (on
the bottom only) of the spoolbox, secured with specialized long nuts,
making the alignment of the box adjustable.  Almost every other
spoolbox I can think of is rigid and does not permit any torsion or
twisting as does the Duo-Art.

In the process of rebuilding the piano action, and retubing the
spoolbox, it becomes necessary to remove the spoolbox, and of course
the original adjustment of those nuts is disturbed.  I have taken to
adding a locking nut under the lower adjustment nut, as it is all too
easy to lose the ideal setting of these nuts after re-installing the
spoolbox.

I cannot give specific instructions for setting the proper alignment
of the spoolbox.  (I do it almost entirely by "trial and error" -- it
can be very frustrating.  I wish there were some sort of laser device
that would aid in getting this adjustment correct!)  Suffice it to say
that the relationship between the roll spool, the tracker bar, and the
take-up spool has to be nothing shy of "perfect".

The spoolbox itself is very flexible.  Even a tiny "twist" of the
spoolbox will result in exactly the issue which Mr. Sharpe has
described; although the tracker ears and tracker pneumatics may be set
correctly, during normal play (particularly on an old roll with metal
flanges) the paper will "warp" as it travels over the bar, and of
course the tracker will attempt to compensate, but it can only move
laterally whereas the real misalignment is due to the spoolbox itself
not being "square".

Try loosening the mounting nuts on the studs which hold the spoolbox
in place and, as a roll is playing, manually "twist" the spoolbox by
grabbing the sides of the spoolbox and observe the behavior of the
paper as it travels over the tracker bar.  When you are able to get
a minimum of "warpage", (i.e., roll lies totally flat while travelling
over the tracker bar) lock the nuts in place.   This is one setting
that cannot be done on the bench -- it has to be done in the piano,
with a roll in place.  It may then be necessary to reset the ears and
or the tracking cam.

Tom Ahearn - Thomas E. Ahearn Player Piano Service
Haverhill, Massachusetts