Notes On Ampico "A" Grand Drawer Roll Tracking Improvements
or "How I saved my rolls from destruction."
Sincere thanks for these ideas go to several experienced rebuilders
and AMICA friends. I hope that I do not embarrass any of them by my
conclusions. They have helped me solve a problem with a piano that
I have been struggling with for a long time. I hope others can maybe
benefit from the troubles I went through to get my piano to track
There is nothing dramatic in any ONE of these improvements but,
little by little, each one adds to the others so the that the final
result is very acceptable.
- Open up the tracking bellows and seal all the inside surfaces and
passages with shellac.
- Verify that bleed holes (Hopefully metal) are exactly the same size
and are free and clear.
- Replace the cloth filters on the two sides of the bellows where the
tracking ear incoming tubes open into the bellows cavity. (You have to
take them off to seal the insides.)
- Use heavy bellows cloth for the hinge (only), across the backs of
the three boards.
- Because of the extreme angles, split the tails of the bellows cloth
over the hinge area into three sections, but stop about 1/4" from the
corners of the bellows. Then use a separate piece of bellows cloth to
cover the tails.
- When reinstalling the assembly in the drawer, seal the screw holes
with PVCE before putting the screws in.
- Swap the cutout and tracker supply tubes running under the piano
so that the tracker system has the larger diameter tube, allowing for
more rapid vacuum flow, so as to give more rapid response to the
tracker. (The cutout works fine on the smaller tubes.)
- Leave the larger diameter cutout rubber tubing in place and switch
to the smaller diameter only when going through the drawer and past the
- Use thin wall tracker bar tubing on the smaller nipples, including
the one on the center tracking bellows to shim up to the larger
- When reinstalling the ears use a thin wave washer between each ear
assembly and the tracker bar so that they can be adjusted by backing
the screw off slightly and they will still remain about in the same
place and won't flop around.
- Set the ears as close as possible to nominal roll width (11 1/4+)
so that the tracker responds as soon as the roll tries to wander any
at all. For rolls that are wider than the ears, the very carefully
calibrated tracker bleeds and sealed tracker bellows allows the system
to respond to imbalance in ear location even though both ears are
Parallel tracker bar, feed, and takeup spools
- The tracker bar, and the two spools have to be parallel! This can
be measured as follows:
Find a tightly wound roll or an empty roll spool for which the diameter
is equal at the two ends. Put the roll in place and rotate it to see
if there is any radial runout. If it wobbles, pick a different roll
until you have one that is true from end to end.
Make a strip of paper about 1" wide by about 30" long.
At the left end, loop it around the roll, over the tracker bar, around
the takeup spool. And back over the tracker bar so that there is a
double layer over the tracker bar.
Place a mark where the two pieces of paper overlap.
Repeat the looping process at the right end. The marks should match.
If they do not (and you are sure that the roll you picked is good), add
or remove shims under the tracker bar mounting screws to get the same
distance for the paper strip on the two ends.
Reroll Air Motor Vacuum Supply
- Slow down the speed of the reroll so the paper has more time to
gently rub against the spool flanges rather than having the flanges
tear into the edges of the paper as it is rewound. With the reroll
speed moving at a slower pace, the whole process is not as violent.
This is done in one of two ways:
Temporarily: move the tempo to near zero and, voila!, watch the reroll
speed slow down and become more gentle. (Of course it takes a little
longer to get to play the next song but we are not talking about a
CD player here!)
Permanently: take the little wooden cover off the top of the governor
and put a spacer between the flexible inner bellows cloth and the cover
so that the reroll bypass valve cannot move as far. (Of course if your
drawer is in the piano, as was mine, it is necessary to completely
remove all the drawer components in front of the governor to get it out.
By this time, I am quite good at doing that!) After some experimenting,
I only let my valve move off the seat about 0.020" (or barely at all).
I found that reroll will work without this valve opening at all but it
then becomes completely (rather than just partially) dependent on the
tempo setting. (The slower the tempo, the slower the reroll.)
Center the Tracker Bellows
- To absolutely balance the forces involved, including any bellows
cloth memory, set the two adjustable sliding rods between the tracker
bellows and the spool box tracking arm so that with a "good" roll
centered with the holes lining up with the tracker bar holes, the
center tracker bellows board is also centered between the two outside
boards. This also centers the system so that during reroll, when the
tracking is turned off, the paper can go straight back onto the roll
spool, just like it came off.
- When retightening the two screw clamps on the sliding rods, be sure
they are tight so the rods won't slip.
Friction in the tracker arm, brake, and other parts of the moving
- To give the tracker system the best chance to respond easily, it is
important that friction in the metal arm that goes around the spool box
and all parts associated with it is minimized.
- The two felt bushings behind the spool box where the arm slides need
to be in good condition and lubricated with graphite or equivalent.
- The left and right ends of the shafts where the roll is installed
need to be oiled and moving smoothly.
- Minimize the pressure that the feed brake applies to the wheel in
the transmission so that the wheel can easily move from side to side
when pushed by the tracker bellows
- Remove the reroll brake entirely.
- Make the tracker bar slippery so the roll will slide over it easier
by giving it an application of automobile wax. Be careful not to apply
the wax in the tracker holes!
Takeup spool flanges
- Shim the takeup spool flanges out slightly, (between 1/64 and 1/32)
to give the paper edges a little more room to run without rubbing on
- (When you get a new roll, or a "new" old roll) Pull off the left
spool flange and wrap a layer of cellophane tape ('Magic Mending Tape')
around the cylindrical hub to build up the diameter so that it requires
some force to be inserted back into the roll core. Use more or less
tape until the flange goes back in but is tight.
- Reinsert the flange and leave a gap of about 1/32 to 1/16 inch
between the left face of the paper and the flange.
Before playing, hold the roll vertically with the right end down and
strike that end repeatedly on a firm surface. Do this until all the
paper is settled to the right end and you can sight across the left end
of the paper and see that the surface is even without any layers of
paper sticking up.
- (This may be controversial.) Gently wind the paper until it is
tight. This holds the paper in place on the spool so that it stays
aligned to the right flange. It also helps the roll move as a unit
when the tracker bellows shifts it. Otherwise the spool may move but
the loose paper takes longer to respond.
- Insert the roll into the piano and push it to the left by pushing
on the _flanges._ Otherwise all your hard work of getting it aligned
to the right is messed up.
Turn on the piano and listen to the music without having to watch the
roll with your hand on the switch!
Fort Wayne, IN