Hello -- after a few questions about organ scales for small crank organs, I made pictures of some of the more common scales as I use them for arranging:  Carl Frei 20er, Alderman 26er, Raffin 31er, German 26er, Hofmann 28er, Gem Roller 20er, Sankyo 20er, Schmieder 16er, Triola.

Each picture shows the notes that can be played on the scale, ordered from lowest to highest; the track on the roll is shown as a number and as an absolute measurement in millimeters from the bass edge.  (For arrangers, this is more useful than showing the notes as ordered on the roll or tracker bar).

One item requires an explanation: The "repetition distance" is the minimal distance from the end(!) of one hole (or pin or slot) to the beginning(!) of another one for the same note so that the instrument produces an audible break, i.e., it "repeats" the start of a note.

For all scales based on the 20er, there is some discussion whether the exact track spacing is 3.85 mm, 3.86 mm, or 3.87 mm.  Herbert Juettemann gives 3.85 mm, some German organ builders claim 3.86 mm. In practice, the difference over 20 notes is at most 0.02 x 19 = 0.38 mm; over the widest scale (Hofmann 28er) it is 0.02 x 27 = 0.54 mm; this is a visible difference, but real organs with any of these tracker bar spacings will play rolls of all three track spacings.

The pictures do not show all measurements necessary for punching.
Missing specifications are, e.g.,

 - maximum distance between two holes or pins if a note is to sound continuously
 - typical raster sizes for punching
 - maximum length of slots if slots are punched (only for Triola)
 - "spiral correction" (of the scales above, only the Triola is punched with spiral correction)

For the 20er Gem Roller, I do not know the track spacings.  Moreover, all the measurements should have tolerances added to them.

I hope I did not misspell a name; in case I did, let me know, then I'll correct the corresponding picture.

Regards
Harald M. Mueller
11 Sep 2005 20:41:18 +0200