BUILDING A WURLITZER 105 BAND ORGAN (Part 13)
by Howard Wyman
As I mentioned early in this article, the only difference in the Wurlitzer Style 104 and Style 105 is the percussion. At this point our organ is configured like a Style 104 and as such sounds just fine. However, the pneumatic mechanisms that are used to strike the drums are intriguing enough that I felt compelled to build them. Also, I have noticed that when I demonstrate the organ most people seem to enjoy watching the drum beaters in operation.
The snare drum and cymbal were fairly easy to obtain. However, the bass drum was a problem. Most present day bass drums are much deeper. I finally found an old bass drum that was close to the right size that a local music store owner had in the back room. According to Bill Black the original bass drums were about 20 inches in diameter and 10 inches deep. The only drum that I could find that was even close to those dimensions was 22 inches in diameter and 8 inches deep. Not only that, it looked like a real basket case. After I restored it about the only original part left was the drum shell. I installed new hardware, new rings and new heads. As for the shell, I obtained some thin maple veneer which I glued around the shell. After it was stained and varnished and all the new hardware added it looked pretty good.
The snare drum beater works on vacuum. It can be seen in Photo A. There are two beaters which are attached to pneumatic bellows and in between the pneumatics one can see two unit valve blocks just like the ones used on the pneumatic chest inside the organ. When vacuum is applied it passes through one of the valves and causes the pneumatic closest to the organ to start collapsing which moves the attached beater toward the drum. As this is occurring the lower end of the beater lifts a pallet valve which causes the first valve to shut off and the other one to turn on which in turn cuts off the vacuum to the first pneumatic and causes it to go to the pneumatic farthest from the organ. This causes the beater attached to that pneumatic to move toward the drum and in the meantime the original beater is moving back away from the drum. Also, when the second valve turns on it sends a vacuum signal through a channel in the mechanism to the first valve which causes that valve to turn on and the second valve to cut off. Then the whole process begins all over again.
All of this occurs quite rapidly and when vacuum is applied to the mechanism continuously it sounds like a drum roll. A very short hole in the music roll on the other hand will cause just one tap on the drum because the vacuum is cut off before the second beater has time to hit the drum.
The bass drum beater works quite differently. The bass drum beating mechanism is shown in Photo B. When the organ is turned on, pressure from the pressure reservoir is sent through the large hose seen just to the left of the handle. This hose is attached to the box mounted beneath the drum shelf. The round opening seen in the side of the box is closed at this point by a leather covered valve seat on the inside. The pressure passes through an opening in the back of the box into the bellows to which the beater is attached causing the bellows to inflate against the two springs shown and moving the beater back away from the drum. It stays like this until a short hole in the music roll operates a unit valve inside the organ which sends a vacuum trigger signal through a smaller hose to the pneumatic on the side of the mechanism. When this pneumatic collapses, its arm pushes on a shaft which moves the valve seat away from the round opening in the side. At the other end of this shaft is a valve which closes off the pressure supply to the box at the same time, and so the pressure in the beater pneumatic escapes through the hole allowing the pneumatic to be forced shut by the springs. The force of the springs causes the beater to strike the drum with a fair amount of force.
And finally, we come to the cymbal. Apparently some of the Style 105 organs had the cymbal mounted at the center of the top and it had its own beater mechanism. Others had the cymbal mounted in front of the bass drum and the beater was tied in with the bass drum beater. There is no hole in the music roll dedicated to the cymbal and so in either case it is triggered by the perforation for the bass drum and strikes simultaneously with the bass drum. Photos C and D were taken of another organ at a band organ rally in Indiana and were the pictures that I used as a model when making my own cymbal beater. Later I got a chance to get a close look at an original Wurlitzer Band Organ and was pleased to see that the cymbal mechanism looked very much like the one in these pictures. In Photo C one can see a wooden arm attached to the upper corner of the beater pneumatic. When the pneumatic collapses this arm strikes the end of a brass rod which passes through to the front of the drum shelf. In Photo D it can be seen that the other end of this rod is attached to an arm near the left end of the larger brass rod running across the front of the shelf. Near the right end of this rod is another arm with a spring attached. Not seen in the photograph is a brass rod bent into a circular shape just slightly smaller in diameter than the cymbal and resting behind the cymbal. The spring at the right end causes this circular rod to be held back away from the cymbal. When the bass drum beater pneumatic collapses and the beater strikes the drum, at the same time the wooden arm strikes the rod and pushes it forward rotating the rod to which the circular rod behind the cymbal is attached. This causes the circular rod to strike the cymbal. The forward end of the push rod is threaded where it passes through the hole in the arm. A hard leather nut is screwed onto the rod behind the arm and another in front of the arm. This provides an adjustment for the striker mechanism.
Having reached this point in the construction I have to admit that I spent more time listening to the organ than working on it. But, there was still work to be done.
Editors note: Howard is a retired electrical engineer and lives in Florida. Most of his career was at the Army Night Vision and Electro-Optics Laboratory. He became involved in mechanical music with the purchase of a non-working player piano. As you will see in his articles, Howard is a highly skilled craftsman. Building your own band organ is a real accomplishment and Howard does beautiful work.
Howard can be contacted at:firstname.lastname@example.org