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MMD > Archives > April 2010 > 2010.04.30 > 03Prev  Next

20-note Organ Music Roll Dimensions
By Wallace Venable

Kent Zacherl said, "... what are the precise dimensions for a tracker
bar that plays Raffin 20-note rolls?"

It may be impossible to give answers that are as specific as you would
like, for a number of reasons.  First, the rolls are not "Raffin
20-note rolls" unless you buy them from Raffin, but are part of a
larger group generally known today as "standard 20er" or "standard
20-note" rolls.  They all conform to a "scale" (a set of notes) and
a set of spacings devised by Carl Frei long before Joe Raffin stopped
building boats and began building crank organs.

Back in 2003, Robbie Rhodes, our regular moderator, posted a note
called "Carl Frei 20er 20-note crank-organ scale" which gives a text
description of both the standard scale and its expansion potential, at 

In 2005 Harald Mueller posted "Small Organ Scales for the Noteur" as  which covers
a wider range of small organ scales, and is, I think, a bit easier to
read.  It contains good information on many other scales.

The only fixed dimensions are those for the rolls themselves:

  20 3-millimeter diameter holes, spaced 3.85 mm apart
  1st bass note is 9.95 mm from edge of paper
  110 mm wide paper

Those are the precise dimensions you need -- the layout of the holes.
The other dimensions do not need to be to any particular set of

Organ builders have made a wide variety of tracker bars to work with
these rolls.  Materials used include wood, metals, and, I think,
plastics.  Some designs are for production with precision machine tools
like milling machines, some are made with drill presses, and some have
probably been made with simple hand drills.  There are a variety of
ways of devising passages in the bar to larger holes which connect to
the rubber or plastics tubes leading to the valves.  In some cases the
bars are enclosed in pressure boxes, in others the organ has rollers to
hold the paper against the bar.  Some organs are activated by pressure
through the paper into the tubes, in others, action is by release of

Generally the tracker bar is longer than the roll width, and some sort
of guide is used to align the holes in the paper with the holes in the
bar.  Many tracker bar constructions use several layers (see 1 & 2
below).  It is possible to use a single block with thin side plates,
and some tracker designs use complex arrangements of brazed tubes.

I suspect you real request is for someone to provide you with detailed
plans and instructions for making a Raffin tracker bar.  Raffin's
specific design might be considered as being something proprietary.
Several authors provide detailed information in books or plan packages
for building other specific designs. It would not be appropriate for
any of the MMD readers to provide you with copies of their copyrighted

Specific packages you might consider purchasing are on the
John Smith designs: 

Mel Wright has prepared a new book on the John Smith organs.

There is also a page of Smith organ building tips on Mel's
web site at 

Tips related to tracker bars are


After building a Smith Senior 20 (which uses a different 20-note
format) I had no trouble working out how I would build a tracker bar
for Raffin rolls.

Another set of plans is Plan 20 key crank organ by Walter Höffle  (Höffle uses
a non-standard spacing for his own 20 note roll.)

Wallace Venable

(Message sent Fri 30 Apr 2010, 20:51:19 GMT, from time zone GMT-0400.)

Key Words in Subject:  20-note, Dimensions, Music, Organ, Roll

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