For a conical bore whistle, like a Copeland, is the conical bore internally maintained throughout the tuning slide, or is that portion of the whistle cylindrical?
On a Copeland low D, I can see that the collar for the tuning slide is more raised on the bottom than it is on the top (near the windway). I’m not a machine shop guy, but I’m thinking that the brass on the exterior whistle walls might be shaved down on a metal lathe to be cylindrical, which would mean the wall thickness would vary along the part that inserts into the collar.
Are there any makers who have thoughts on this process, or knowledge on how the Copeland slide is made?
The specific question of how Copeland whistles are made is covered very well in the link kkrell just gave. But I think it is worth adding a general comment that there are two basic bore designs that address the acoustic problem of keeping both octaves in tune. These are often described as conical bore or cylindrical bore, but this terminology is really a bit misleading. They could more accurately be described as tapered body bore with a cylindrical head bore and tapered head bore with a cylindrical body bore. This applies both to flutes and whistles.
It is easier to see what is going on with a flute (because the most common flutes are low D whereas the most common whistles are high D and hence much smaller), where you can see that the head and tuning slide are clearly cylindrical, with the tuning slide employing telescoping cylindrical tubing with parallel walls, and the body is reamed to whatever taper the maker wants to use to address the balance of harmonics and the ergonomics of finger hole size and placement. In contrast, on a Boehm flute the body is cylindrical and the taper is in the head (often referred to as a parabolic head) and is more hidden, with the bottom part of the head bore being cylindrical and serving as the tuning slide. On many of the high end whistles the acoustic design is more similar to the Boehm flute. They use a cylindrical body and have a very subtle and small taper in the head, which is sometimes simply a step rather than a taper. It is short and hidden inside the top part of the bore near the window, and sometimes disguised by a change in bore and external shaping.
But my point is just to say that a conical body bore does not necessarily imply a problem for making a tuning slide, so long as the range of the slide can be accommodated in the portion of the bore that would normally be cylindrical for acoustical purposes.
Thanks for that quote. I’d read it before, but the tuning slide bit goes by so quickly I didn’t catch it.
“With the Low D and others, the head joint and body are two separate
tapers. We prepare a cylindrical piece of tubing for the tuning slide and
solder it to the body”
That makes me wonder if the head joint has a separate taper ratio than the rest of the body, or if he’s just saying it’s two separate pieces with the same taper. I’d assumed the whole length was a consistent taper made from two sections, but it’s hard to tell around the windway, where the blade is pressed down, causing that little bulge on either side.
Maybe this will help. On mine, the following measurements (Outer Diameter only, via calipers) in inches:
Immediately above windway barrier: 0.966
Immediately below windway barrier: 0.963
Immediately above slide: 0.880
OD of inner part of slide: 0.875
Slide: 0.943 (definitely thicker piece overall). [Length of this cylindrical section: 1.666]
Immediately below slide: 0.875
At Hole 1: 0.825
At Hole 2: 0.810
At Hole 3: 0.785
At Hole 4: 0.760
At Hole 5: 0.740
At Hole 6: 0.715
Extreme bottom at foot: 0.670
I’d say this indicates a taper on both pieces, with the top (moves) & bottom (fixed) sections fitted into the slide having what appears to be the same OD.
I believe I now have finished editing the numbers.