Tubular bells, like most percussion instruments are simplicity themselves; they are just a tube of brass normally reinforced at the top with a cap. However, like most percussion instruments, they are little understood, and the simplicity of design belies the challenges faced by an instrument maker to deliver a good sounding instrument. If it’s just a tube with a lid, how will I know whether it will sound good, and what can I do if it sounds rubbish?
I have yet to be convinced by any claims that manufacturers make in marketing about their ‘fantastic tubular bells. What they fail to publish, are reasoned arguments, supported by research and data. However they are not writing publications for me to read, they are writing to sell instruments to musicians who go on to accept their statements as fact [suckers!?]
So what is the solution? Research. Everything I do, I document; it is from this accumulation of data and observations that I gain a deeper understanding of all the instruments I work on. Furthermore, it provides the platform from which hypothetical improvements are made and subsequently tested. By improvements I mean manipulating an instrument to improve its musical timbre.
To make a set of tubular bells by mass production, a saw to cut the tube to a predetermined length is needed, and a drilling machine to drill the holes in a set position. There may or may not be a secondary tube for the cordage to pass through. To make the caps, a computer operated lathe will be used. The caps are then pushed into the tube using pneumatic rams. Polish and chrome; job done. One musical instrument made!
My method of making tubular bells is very similar. Starting with a suitable length of stock tube and referencing my accumulated data, the tube is cut a little longer than the longest bell of that pitch that I have ever seen. Why?
The first reason is that no two lengths of brass are identical. The assumption that materials are completely uniform is a fundamental flaw in the concept of mass produced musical instruments.
The second reason is to accumulate more data. Because I can only get two, possibly three bells out of a length of tube anyway, I cut them as long as possible. The result for me is two or three times more data is acquired as I raise the bell to pitch by shortening the tube. The extra length also provides opportunities to experiment and still be able to make a bell at the correct pitch.
Now I have an oversized tube I clean up one end clean up one end. This has to be done by hand, because I don’t have the room for a lathe big enough to take a tubular bell (unsurprisingly), so it takes a me a lot longer versus factory.
After I have the holes drilled, I remove all the sharp edges, making them rounded in cross section. This prevents the metal from slicing through the cord. It is this attention to detail that takes me time, but saves my customers time and frustration.
Before the cap goes in, I stamp the tube with the pitch of the bell rather than the cap which is the playing surface. In several instances, my customers accumulate a complete set of bells over many years, and I want to give them consistency of design, so I have a little pattern to get all the stamps in the right place.
What I never get is perfection. It’s bloody hard to get the stamp perfect, I used to get moaned at by my boss when I worked at a shop for wonky letters. Over a decade later, I still find it impossibly difficult and it still upsets me when they are not right, but I’m better at living with the disappointment and view it as a mark of humanity as opposed to the machine.
In the photo, I am checking the angle at which the chamfer is cut.
The cap is made to a sliding fit into the tube. The cap is solid brass, if it has to be forced into the tube it is the tube that will expand. This expansion of the tube creates internal stresses and makes the brass less ductile, and it is the reason why the tubes split at that point. In my view this is another indication of the embarrassing lack of knowledge displayed by the major manufacturers!
This blog post continues in 1206: 1.1/2″ Tubular bell (part 2)