I designed the Player Piano Co. (Coinola) spool frames in 1979, using
a reversible play gear-motor from Grainger which is still available.
The rewind motor was a powerful, temperature-protected cash register
motor of some sort, from National [Cash Register Co.], that had been
specially made for them and purchased in a lot of surplus by PPCo.
This motor was responsible for a 40-second rewind, and made it very
convenient for the user to buy two of them if he wished to create an
instrument with double the music on it. It was reversible by reversing
the gears in its box.
I also designed a system that would multiplex the rolls together,
without the need for a note cutout system. SOFI (the large orchestrion
I presently own) also has two of these spool frames, multiplexed and
ready to play at all times, with only roll paper covering their tracker
The spool frame comes in two basic styles: "G/A" type frame, and an "O"
style. The "G" frame runs the normal player piano way, with the
tracker bar in front of the spools and both spools turning clockwise to
play as viewed from the left side. In the "O" style frame, the tracker
bar is inboard between spools and the spools travel counter-clockwise,
viewed from the left side. ("O" roll paper is reverse-wound.)
These spool frames have clutched take-up spools to make a gentle stop
when rewinding fast -- as they do. They are also designed to favor
play over rewind, and cannot continue rewinding if for some reason the
paper lifts off the tracker bar momentarily at the end of rewind when
they hit the "forward to play" hole.
The reason I would suggest using these spool frames yet today is
because they are so reliable and heavy, and control the paper so well
in forward or reverse. They use heavy ladder chain drives and have
given few problems in the last 20 years. The one problem I am aware of
are the plastic pouches in some of the valve blocks and the one-way
in-line valve (early) versions of the circuit. This was replaced by a
one-way ball check. PPCo's valve blocks today are pretty good, from my
experience, and all have leather pouches.
These spool frames work well. Not because I designed them (I don't get
a dime from their sale), but because I know how much different they are
from any other spool frame available today or yesterday, and I imagine
that they will remain the most powerful and reliable frame available
for years to come. No rubber band drives or slipping linkages, no
gruesomely slow rewinds and temperature buildup problems, and they're
easy to adjust, or to disassemble if desired.
When testing them, I built a test setup using two frames (a G and an O)
multiplexed together with test rolls on each. I turned them on and let
then cycle continuously, day and night for 6 months without a hitch
(except when the power went out). They ran their cycle about every
minute. We could have let it run for 10 years. It never missed a
They can also be converted by the builder to just about any width roll
by remachining the stretcher bars and cutting the take-up spool to
whatever width you prefer. Of course, you have to provide a tracker
bar. But you will notice that the tracker bars are designed to be
removed, so if you wish to take the spool frame out, you can leave the
tracker bar hanging on its tubing in the instrument.
There is only one thing I will warn buyers about. I have run into
tracker bars having some of their holes clogged with solder. So check
first, and if you see that problem, heat up the nipples and knock out
the melted solder through the front of the bar. This was caused by not
having the nipples weighted down as they were soldered in, and/or their
mounting holes too large.
Also, sight down the bar. After the nipples are soldered, you will
notice the bar will be curved concave. Place the bar on two 3/4" blocks
at its ends and, using a mallet against a maple hammer block notched for
nipple clearance, hit the bar a few times in the center to correct for
the curve, caused by the solder.
These spool frames today cost about $650 at last check, but believe me,
they are worth it. You do not want to be running into spool frame
problems, and face untubing the instrument again, just to get it out
of the machine to fix it, only to face the same ordeal again and again,
as a little "O" ring drive belt takes its set and gets loose or breaks.
Fixing that problem just once will cost you a lot more than the price
of one of these good spool frames. Do it right, and do it once.