Currently, I have designed 3 different tapers that cover the spectrum in terms of taper length and taper size. From my experiments with these tapers, I will be able to narrow down what characteristics they each produce, and then I will design new tapers to try to improve on the first 3. With the aid of my new CNC lathe, making new leadpipe mandrels will be much faster than it used to be, which will allow me to quickly see the results of my ideas. Needless to say, I am very excited to get my CNC gear setup and tested!
Below is a run through of the process I use to make my leadpipes. There are a few different ways to make a leadpipe, and my way is a traditional tube drawing process. Other ways of making a leadpipe are to form it from a flat sheet and braze it together with a seam, or machine a piece of brass rod using custom made drill bits that are extra long, and tapered to the leadpipe specs.
First I anneal the tubes to soften them. After they cool, I place them on the leadpipe mandrel that I want to use and I start hand drawing them down to size with the draw plate that is mounted in the vise. The tubing hardens as it gets worked, so the process of annealing and hand drawing gets repeated about 5-8 times.
Hand drawing doesn't get the tube all the way to final size, but it makes the final process easier.
I had 6 leadpipes to make, and the first 2 went perfectly. The remaining 4 failed on me because I had not hand drawn the tubes down far enough before drawing them with my drawing machine.
I prepped the 4 failed tubes again and they all succeeded in the final machine drawing.
The machine I draw the leadpipes with is handmade, and works really effectively. After the tubes are hand drawn, and the tips of them are formed to grip the leadpipe mandrel, I thread the tube and the mandrel on to the drawing machine and pull them through a softened steel washer. The steel washer slides over the tube and compresses and stretches it to fit the dimensions of the mandrel exactly. This is how most instrument makers make their leadpipes.
The leadpipe is then removed from the mandrel by drawing it backwards through the machine with a thick steel washer that doesn't deform, and then the mandrel is cleaned, prepped, and cut to length.
I have 2 leadpipes of each of my 3 tapers, so these pipes will all be tested to find the perfect fit with each of my 4 different bell flares.
More on the bells later.