Drilling Vulcanite Rod

Drilling vulcanite rod is the first and most decisive step in making a pipe mouthpiece. Although the mouthpiece looks, from the outside, like nothing more than a shape, its real function is carried out by the smoke channel inside it; once that channel is drilled crooked, rough, or off-center, correcting it afterward is next to impossible. That's why craftsmen open the hole before they ever shape the rod.

Nature of the Material

Vulcanite is a hard mass obtained by vulcanizing natural rubber with a high proportion of sulfur over a long period; it's also known as ebonite. The sulfur ratio varies over a wide range depending on the formulation, and the region that gives the best mechanical strength is generally taken to be around one third. Industrial-scale use of the material became established after Charles Goodyear developed vulcanization, when his brother Nelson Goodyear obtained a patent for hard rubber in 1851. Vulcanite cuts cleanly on the lathe and polishes well by hand; on the other hand, it's sensitive to heat. Worked at high speed or with a clogged bit, the surface burns, gives off an odor, and discolors. Its comparison with other materials used for mouthpieces is covered in the mouthpiece materials entry.

The Logic of Drilling

The operation is carried out on a metal lathe, where it isn't the bit that turns but the material. The advantage of this reversed arrangement is centering: when a rod chucked in a self-centering chuck spins and the bit is only pressed lightly against it, the material draws the bit toward the middle of its own axis. That's why the face of the rod is trued up first; a crooked face throws the bit off to one side on the very first contact. Once the starting hole is opened, the tailstock is locked and feed continues under controlled pressure.

The channel isn't opened at a single diameter but in stages. The end of the mouthpiece that sits against the pipe is widened into a funnel shape with a tapered bit — reportedly around 9/64 inch — and since this widening needs to stop roughly a centimeter short of the rod's other end, a mark is made on the bit's shaft beforehand. The remaining long section is finished with a fine 1/16-inch bit. The channel thus ends up with a cross-section that starts wide on the pipe side and narrows toward the bit end. The general principles of drilling are gathered in the drilling on the lathe entry.

Heat, Chips and Surface

The main risk in this operation is heat. Because thin, long drill bits have shallow flutes for clearing chips, debris builds up inside the hole; the accumulated chips increase friction and the vulcanite quickly burns, leaving an odor and dulling in color. To prevent this, the lathe is kept at the lowest speed, the bit is withdrawn and cleaned frequently, and feed is achieved with patience rather than pressure.

Once the hole is opened, the inner surface remains rough. A common fix is to wrap a strip of fine sandpaper around the bit's shaft and smooth the inside of the channel, again at low speed, working through progressively finer grits. The final section widened with the tapered bit can't be worked at this stage; the wrapped bit doesn't reach that far in. This isn't considered a shortcoming, because that part will be reopened anyway when the mouthpiece is fitted to the pipe. The drilled rod then moves on to tenon turning and exterior shaping — in other words, to mouthpiece work.