Fabricating a Bassoon Boot Cap

One of the really great benefits of working in the field of musical instrument repair is that every day brings new experiences. Such was the case a few years back when I received a Puchner “Artist” model bassoon in the shop for a complete restoration. It was in sad shape; both the center bass-joint tenon and the wing joint tenon were destroyed, a number of key guards were missing, dry rot in the boot joint, the finish looked as if someone’s cat had used the instrument as a scratching post, and to add insult to injury, the boot cap was nowhere to be found

My first impulse was to contact the U.S. Puchner reps at Custom Music in Royal Oak, MI. They informed me that the boot cap was an item that had to be special-ordered from Germany, and would take perhaps months to acquire. I began to get seriously discouraged at this point, but when they informed me that it would cost $275 (back then) plus shipping, I knew that I would have to bite the bullet and make one from scratch.

My first move was to retrieve some of our own bassoons from stock and study their boot caps. I knew it was too much to expect that a boot cap from one of these manufacturers would fit straight across. . . . . no such luck. I was convinced at this point that I must be dealing with a conspiracy. After further examination, I could see that there was nothing particularly complex about these caps, albeit they were of different dimensions. I simply required something that would fit snuggly around the end-plate offering protection to the crook. And of course, it had to be outfitted with a center rib (with strap ring hole) and look like it belonged there. My mission was clear.

Most of the caps in stock were manufactured of 1/16” brass stock and were nickel-plated. So, my first task was to visit the local hardware store and purchase some brass sheet stock. They sold me a pre-packaged piece of 1/16” brass sheet stock measuring 2” X 10” for approximately $5.00. To establish the exact dimensions, I made a flexible mylar template that fit perfectly around the crook plate, and was long enough to comfortably exceed the end of the crook. Once the template was taped together in place, with the ends perfectly butted-up against one another, the final template was essentially a perfect cylinder.

Next, I removed this mylar cylinder and laid it flat on my brass stock. The result, of course, was a physical two-dimensional representation of the walls of my future boot cap. I then placed this template on top of the 1/16” sheet brass and carefully scribed around its boarders. To my delight, the length required to exceed the crook was exactly 2", so I only had to make one cut. I then cut the brass a little beyond my scribed line with a jeweler’s saw. (Be careful to avoid putting scratches or vise jaw marks in the brass) My next step was to carefully dress the edge with a fine double cut pillar file, followed by polishing this edge on the belt polisher (#220). I was now ready to prepare for the bending process.

To begin with, I slowly annealed the brass sheet with an open-flame soldering torch (#2 tip). This should be done on a flat surface. Allow only enough heat to bring the metal to a dull red color, then allow the brass to cool slowly. Do not over heat or cool the piece too rapidly, avoiding distortion. Once the sheet has cooled, I began the forming process. I used a large dent mandrel supported in a large vise. In the absence of a large mandrel, you could use a galvanized steel pipe, for example, as long as its radius is slightly smaller than that which is required for the boot cap. I used a large leather mallet to gradually form the brass sheet into a perfect cylinder. When the ends of the brass sheet met evenly and perfectly. Next, I brazed the ends together with a Turbo-Torch Air-Acetylene torch outfit, using Ezy-Flo Silver Brazing wire with a Borax flux. Remember, Ezy-Flo does not have gap-filling potential, so I had to make sure that the ends of the sheet butted-up perfectly before brazing them together. I then pre-placed the brazing flux on the seam and proceeded to braze it together, allowing the piece to cool slowly.

I was now ready to finish precision-forming the cylinder into the exact shape of the crook plate. I found this to be pretty much a try and re-try process. I wanted the result to be an oval-shaped cylinder that would fit perfectly over the crook plate with a moderate amount of resistance. If you intend to nickel-plate the finished cap, then the fit at this point should be a little loose to allow for the thickness of the plating. (This should be allowed-for when laying-out the dimensions initially)

Next, I made sure that the bottom of the cylinder exceeded the crook comfortably and was perfectly flat. If yours does require adjustment, gently polish it with #220 emery cloth laid on a flat service. I then proceeded by setting the cylinder on the remaining flat portion of the 1/16” sheet stock, and carefully scribe around the base of the cylinder. Next, I cut this oval out of the sheet stock, again allowing a little extra material, which would be dressed down later on the belt polisher. I then applied a small amount of brazing flux to the edge of the cylinder and clamped this oval piece to the flat stock in preparation for brazing the pieces together. After brazing around the base of the boot cap, I carefully trimmed the excess material around the circumference of the cap.

The last step was to prepare a ¼” rib, long-ways across the center of the bottom of the cap. This was cut from the remaining 1/16” sheet stock. I applied some flux to the surfaces, clamped the piece in place and brazed it. After the piece had cooled, I shaped the rib with the polishing wheel, and drilled a 1/16” hole on the inside of the rib to accommodate the strap ring. I then began the final polishing and buffing of the entire end cap. Since the cap was to remain in brass, I cleaned it thoroughly and sprayed it with a clear epoxy. To my satisfaction, all had gone according to plan, and the boot cap fit snuggly on the end of the bassoon and functioned perfectly. Had I wanted to have the piece nickel plated, or silver plated, I would have had to ship it to Anderson Plating in Elkhart for this final step. The entire process took me just under 2 hours. With a $75 per hour shop rate, I didn’t save any money by fabricating it myself, however, I did avoid having to wait, perhaps several weeks getting the part shipped from Germany.