From Music to Cylinder: An Eight Step Method
by
Charlie Hind
The first question most people ask after seeing and hearing a music box for the first time is "How did they get all those pins in the right place?" In 1986 I, too, was asking that question. I had decided to make a music box, and I knew almost nothing about the subject. What had led me to this point was a keen interest in musical instrument making, a fascination with indexing and gearing, and an assortment of machine tools that I had accumulated for making various other musical instruments. A music box seemed to be the perfect medium through which these three attributes could be brought together; and, luckily, I had no idea how complex it was going to be. By the time I had figured that out, I was hopelessly obsessed.
Through the interlibrary loan program I borrowed one of Arthur Ord-Hume's books
on music boxes and there discovered the existence of The Musical Box Society
International. I was on my way. After joining the Society and buying most of the
books that were available, I gradually began to realize that I wasn’t going to
read about how to make a music box. On the subject of putting music on
cylinders, I found that much had been written, but little said. By this I mean
that reading the literature didn’t tell me what I needed to know in order to be
able to drill a cylinder in my shop with my tools. In designing other musical
instruments, I have found that processes used in the past are not necessarily
applicable to what I can do in my shop. I have become accustomed to figuring out
how to achieve the same results with the machines and skills (or lack of) that I
have at hand.
Having a rotary table graduated in degrees, I decided that the most practical
method of locating the pins on the cylinder would be to convert every note of
the music into degrees which could then be dialed into the rotary table. The
nice thing about this system is that it allows all of the work to be done on
paper, then checked and rechecked before the cylinder is drilled. It is a
tedious task, but it does have one redeeming quality---it works, and it works
very well.
The system is broken into eight distinct steps; and to demonstrate its
application here, I will show how I used these steps to pin Bach’s Three-Part
Invention No. 11 in G Minor (Figure 1) onto a two inch diameter cylinder.
Figure 1.
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Step 1.
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Determine the shortest commonly used note value in the music. Referring to Figure 1 we see that the sixteenth note is the shortest commonly used note value.
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Step 2.
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Determine the maximum number of times this note value can occur in each measure. A time signature of 3/8 allows a maximum of six sixteenth notes per measure.
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Step 3.
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Determine how many measures of music are to be pinned. Although Figure 1 shows only the first five measures of this piece, I actually pinned 36 measures. Before any music is chosen, however, the length of time for one revolution of the cylinder must be known. This, of course, is determined by the gear ratios. Obviously, if too long a piece of music is chosen, it will sound too fast; and a short piece will be spread over a longer than normal time and sound too slow.
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Step 4.
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To determine the total number of possible pin locations (divisions) around the cylinder’s circumference, multiply Step 2 times Step 3, (6) x (36) = 216 divisions.
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Step 5.
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To determine the distance, in degrees, between each of these divisions (sixteenth note locations around the circumference of the cylinder), divide 345º by the total number of divisions (from Step 4), 345º divided by 216 divisions = 1.597º. For practical purposes in indexing this amount with my rotary table, I rounded it to 1.6º.
Although there are 360º around the cylinder’s circumference, a blank space must be left at the end of the tune to allow the cylinder to move to another tune, and for the comb to remain at rest while the music box is not playing. I used 345º for a two inch diameter cylinder because it leaves approximately ¼" of blank space at the end of the tune. The math involved is as follows: 2" x Pi = 6.28" (circumference of the cylinder), 6.28" divided by 360º = .01745" per degree; (360º - 345º) x .01745" = .262" of blank space. Rounding 1.597º to 1.6º makes only a minor difference in the amount of blank space left at the end of the tune: 1.6º x 216 divisions = 345.6º, (360º - 345.6º) x .01745 = .251" of blank space.
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Step 6.
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To determine the exact location, in degrees, of every division around the cylinder’s circumference, add the number found in Step 5 (1.6º) to itself continuously until you reach 345.6º (1.6º, 3.2º, 4.8º, 6.4º, etc.- see Figure 3.) These numbers represent the location of every possible sixteenth note around the cylinder’s circumference and are produced very quickly on most scientific calculators in the following way: press (1.6), then press (+), then press (=) (=) (=), etc. Each time the (=) button is pressed, 1.6 will be added to the last total.
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Step 7.
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Assign each comb tooth a pitch and a number (Figure 2). The determination of which notes will be on the comb is simply a matter of looking through the music and seeing which notes are used. When a note is repeated in rapid succession, two or more comb teeth are tuned to that note.
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Step 8.
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Assign each degree location (from Step 6) the appropriate comb tooth numbers. This is where a thorough knowledge of musical notation is essential. One must understand the relationships of the durations of all the various note values. A chart (Figure 3) is presented which will be used at the machine where the cylinder is drilled.
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Figure 2.
The numbers underneath each note signify which comb teeth are tuned to that note.
Figure 3.
This chart correlates longitudinal and circumferential coordinates.
It is a fairly straight forward process to cross reference Figures 1, 2, and 3 and see how every note corresponds to a particular degree location in Figure 3. While it is beyond the scope of this article to explain the basics of musical notation, here are some comments about certain areas which might raise questions.
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Measure 1.
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The music begins with G in the bass clef. Look at Figure 2 and see that comb teeth 31, 32, and 33 are tuned to this note. Now notice in Figure 3 that two holes are to be drilled at 1.6º, one at the 31 position and one at the 32 position. These holes must, of course line up exactly with comb teeth 31 and 32. While only one G is written in the score, I used two teeth tuned to the same note whenever possible to enhance the sound of the musical arrangement. Now referring to Figure 1, the second note to be played is D in the treble clef. In Figure 2 comb teeth 86 and 87 are tuned to this note. Figure 3 shows that holes are drilled at 3.2º in positions 86 and 87. The third note played is B flat in the treble clef. Comb teeth 71, 72, and 73 are tuned to this note. Holes are drilled at 4.8º in positions 71 and 72. On the third beat of the measure, two notes are played simultaneously, so four holes are drilled at 8.0º. No notes are played on the last half of the third beat, so the 9.6º location is left blank.
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Measure 2.
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Again, the last half of the third beat is not used (19.2º).
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Measure 3.
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The D is not repeated at 20.8º because it is tied over from measure 2.
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Measure 4.
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The C that is tied over from measure 3 is not repeated at 30.4º. The second B flat in the bass clef (33.6º) is played with a different comb tooth than the first B flat (30.4º) to prevent buzzing caused by the same tooth being plucked too quickly while it is still vibrating.
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Measure 5.
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Tooth 68 is used for the A (40.0º) because it was not used for the A in measure 4 (35.2º). The F# is not doubled because it occurs again at the beginning of measure 6.
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This process of assigning comb teeth to degree locations is continued in the same way throughout the piece of music. When all the paperwork is completed, the cylinder to be drilled is placed between centers in the lathe. The rotary table is mounted on the outboard side of the lathe headstock and connected to the hand wheel of the collet closer so that when the rotary table is turned, the lathe spindle also turns. The holes are drilled with a Foredom flexible shaft hand piece mounted horizontally on the lathe cross slide. The drill is fed into the cylinder with the cross slide hand wheel.
Longitudinal indexing is achieved by moving the lathe carriage left and right.
A dial caliper or digital readout is mounted to the carriage to insure precise
repeatability. This longitudinal spacing is, of course, determined by the length
of the comb and the distance between the tips of the comb teeth, factors which
are influenced by the complexity of the music, the number of tunes being pinned
and the whims of the maker.
In closing, there are many different ways to perform most operations in the
shop. The best way is usually one that assures the desired results with the
least amount of effort. This is not to imply that using the system I have
described here is a small amount of work. On the contrary, it is a staggering
sacrifice of time and mental energy.
So, what is the BEST way to drill and pin a cylinder music box? ANY WAY THAT
WORKS!
