Tracker Bar Hole Spacing

(from a Letter by Glenn Grabinsky to Art Reblitz)

Glenn Grabinsky on Tracker Hole Indexing

Glenn Grabinsky, an automatic music collector and a fine machinist, has interviewed numerous old-timers and has conducted extensive research into automatic instruments and their makers. In August 1998, Art Reblitz asked him if he knew where the Wurlitzer engineers came up with the unusual hole spacing for their tracker bars in 65-Note Automatic Player Pianos and orchestrions, and styles 125, 150 and 165 band organs (about 49 holes per 6 inches, or about 0.1227” per space).

He then sent Art the following history, explaining not only on Wurlitzer’s peculiar spacing, but also detailing the origin of most tracker bar spacings ever used in the United States. The letter covers other topics as well, and is universally quite informative and interesting from beginning to end, as well as being technically astute and useful. Glenn briefly explains the measuring systems and mechanical limitations that determined how and why various die plate layouts for music rolls came about. His comment are suggested reading for anyone contemplating understanding the art and mechanics of laying out a music roll punching die plate.

Acme Novelty Machine Works letterhead.

August 1, 1998

Mr. Art Reblitz

Dear Art,

Sorry for the untimely response to your letter. The weeks just whiz by with the kids, work, and of course the summer heat wave. In any case, I want to thank you deeply for the Clark Orchestra Roll minutes. What a sad story at the end. It really is amazing how they managed to last as long as they did. One question, how did the minutes manage to survive? I have enclosed a copy of a handwritten note that I found many years ago in a roll box that came with a group of I believe 13 rolls with a piano I bought in Pennsylvania. Pretty sad, begging for payment at the end, written in pencil on the back of an old roll invoice. This must have been right before they shut the doors. All the rolls were of the black label variety, and poorly punched (incomplete chains, etc.). I have kept them all together as a group, figuring there is some historic significance to this being probably one of the last shipments made.

Now, ... to roll hole spacing. First the easy one, Mills. The exact spacing is 35 holes per 4 inches, which comes out to 8 3/4 holes per inch. Kind of funny that their race horse piano roll is 8 3/4" wide. Some times I have found (with organ rolls in particular) it is a good idea to look for whole number spacings in inch multiples. I actually got this spacing from an original piece of paperwork giving the exact spacing regarding die plates.

The unit of height of a line of printers type is the "point." 1 point = 1/72 of an inch. Why someone choose 1/72 of an inch is anyone's guess. However, since it is divisible by 12, like the rest of our system, I guess they figured it was
pretty versatile. 6 point type is 1/12 inch high, 8 point 1/9 inch high, 12 point 1/6 inch high, etc. For whatever it is worth, the most common sizes are as follows; 3 1/2 point (brilliant), 4 point (Excelsior), 4 1/2 point (Diamond), 5 point(Pearl), 5 1/2 point (Agate), 6 point (Nonpareil), 7 point (Minion), 8 point (Brevier), 9 point (Bourgeois), 10 point (Long Premier), 11 point (Small Pica), and 12 point (Pica). Wheeeeew!!!!!! Also, for what ever it is worth, the vast majority of typewriters ever made, both here and in Europe, are either 12 or 10 spacing to the inch. I was told by an old timer, Mr. Floyd Orman, who was the son in law of L.B. Doman and worked for Amphion, that the spacing was based upon existing printers scales, since both graduated paper, scales, and rules already existed and made life a little easier to work with these things when the roll arrangements were all drafting board compositions. This made totally logical sense to me, in fact, it is interesting that some of the principle owners and management of Amphion were from the printing
background and owned a typewriter company!

Concerning the Jacquard loom key frames; A few weeks back I got some correspondence from a starry eyed Amica member who wants to cut his own arrangements on a Leabarjan type machine. He would like to copy one of my machines, and his friend who would build it is, of all things, a repairman on Jacquard looms here in the Tri-State area. Maybe he will be able to shed some light on this matter. Years ago in Wallyworld (Bellm's), there was a perforating machine mounted on a cast iron base which had "Mangels" cast into it. People had assumed that this was a band organ roll or book perforator. In actuality it was Jacquard loom book perforator. I believe that it found its way into a black hole in Chicago. If it is accessible to you for inspection, you may want to check it out for spacing, etc. I had photos of it at one time, but unfortunately they were loaned out and never returned.

Ahh ... Now we come to Wurlitzer. The approximate spacing is 0.12271846" per space. This linear spacing can never be expressed as an absolute value since it requires the use of Pi in the formula. Now let me digress a little. In the 19th and early 20th centuries a common way to index things in machinery was by a gear and rack set up, versus the lead screw arrangement we more commonly use today. A tight fitting rack and gear would usually give more accuracy than a loose lead screw with backlash, etc. I have in my possession quite a bit of original Amphion tracker bar and die plate tooling, so I can verify this. Gear standards were somewhat helter-skelter until around WW1. There was the Module system used in Europe, the circular pitch system, and the diametrical pitch system. The two most commonly used systems were the Module system on the continent and the circular pitch system in the U.S. Circular pitch is real nice because the factor Pi is built into the gear diameter, so that the resultant spacing between teeth on a rack is an even whole number (i.e. 1/10 circular pitch would be 0.10" per tooth, 1/5 would be 0.20" per tooth, etc.) With the Module system or diametrical pitch, you can accurately index with a gear and rack, but the factor Pi (3.14159265...) comes into play, so you never get a nice even number for linear spacing of the teeth on the rack.

I am quite sure that Wurlitzer aimed for a standard spacing of 1 Module, which would be 0.12368475" per space. So why the very small difference? There was a common error in gear making at the time (I find it commonly in musical boxes, particularly stuff from Germany and the U.S.) in which the outer diameter of the gear was used in the calculations instead of the pitch diameter. The error is usually on the side of two teeth less per gear. The gears will work and mesh, but rather than rolling on the tooth contact they slide. I attribute most of the wear and destruction I find in Music box motors not due to over usage or lack of oil, but just poor original design. With this in mind, the actual spacing of the Wurlitzer scale is exactly what the spacing would be with the "gear error," 0.99218 Module. As you can see, this error is small (about 0.78%), but after 65 holes it adds up! Magically, this "error" can be exactly converted to U.S. diametrical pitch and comes out to 5/8 of a 16 pitch rack tooth space. So yes Virginia, there is an absolute after all, it is 0.0390625 x Pi per space. Maybe they did plan for this 16 pitch spacing (a standard 40 turn dividing head with a 25 tooth 16 pitch gear will give this exact spacing with every tum of the crank), but my experience with what I have found and had to make for Reginas and Polyphons tends to lead me to the "gear error" conclusion. Talk about esoteric! But I figure you are like me and do not like unsolved mysteries, so there, you got stuck reading this drivel!!!

That's the roll spacing biz. Concerning metric vs. inch on European instruments; my experience with musical boxes, phonographs, and scientific instruments of the 19th/early 20th century is one of confusion. It seems to me that regionally, different areas were using different systems and sometimes mixing them together (the Germans in particular were real crafty at this). The metric system is a lot older than we are taught in school, and was being used in France at least for quite a while before the French Revolution. Meanwhile, most European countries, or regions, had their own inch system. The French had an Inch (= 1.065 US inch), the English had an inch (= 0.99999 US Inch), and I am quite sure those lads in Bavaria were stitching up their lederhosen to some Teutonic Inch. In musical boxes, primarily cylinder, the common measurements are based upon the French inch (Pouce) and the subdivision of the French Inch, the Ligne (Line) which is 1/12 of a Pouce (= 0.08875 US inch).

I went through my files and copied for you some Ampico/Amphion correspondence relating to music rolls, tracking problems, etc. As you can tell from reading between the lines, Wurlitzer, Estey, Doman, and the boys at Ampico were a circle of friends. Aeolean and Austin were not (the one phrase in a letter from Doman is the biblical term that Austin and the others can go to hell). Also, from original papers I have, and from first hand recollections from Mr. Orman, Ol' Mr. Stoddard was not a happy camper with anyone outside of his immediate circle. It was interesting to note in the Clark Orchestra Roll minutes of February, 1936, the mention of the Seaman Paper Company. As you can see in the attached correspondence, they were the paper supplier to Ampico. I have quite a few rolls of NOS Ampico paper, as well as 2 sealed rolls of Clark type paper 16" wide. If I ever get around to cutting any rolls, I will use this for my "special projects." It is interesting to note that while Doman was still in the employ of Amphion, one of the things that American Piano seemed interested in was the development of a multiplexed reproducing organ player. Whether they intended to market it themselves, or just supply people like Estey, etc., is up to speculation at this time.

Best Regards,

Glenn Grabinsky