Degrees of taper

Whistle
1

We tend to separate whistles into two broad categories - cylindrical and tapered. But turns out it’s not quite that simple. A colleague and I have been delving a little into the topic, and have so far identified four different categories:

  1. Cylindrical whistles. No taper. The head end of the tube and the foot end both have the same bore. Most whistles are cylindrical.
  2. Slightly tapered whistles. The foot end of the tube reduces to around 90% of the head end. Examples include Thornton (Martin) and Carbony.
  3. Strongly tapered whistles, possibly (probably? inevitably?) with terminal flare. Swayne and my experimental pic-whistle come in at about 70% and 80% of the head bore.
  4. Full length tapers. Clarke’s D and Sweetone D are examples. They taper all the way from head to foot. Their foot bores are 60% of their head bores.

Are there more categories than the four we describe?

And can we identify more models that fit into these categories?

I was intrigued by the 2. Slightly tapered whistles. Is that very mild taper of much significance?

And I’d have to say I’m not immediately impressed by 4. Full length tapers. But perhaps there are some who can perceive advantages that I can’t?

2

I no longer have one to measure, but you might enquire of Phil Bleazy what type of taper he utilizes.

3

Can anyone with a Copeland provide info on which category those would fit? And is the taper similar over various keys?

Best wishes.

Steve

4

The outer diameter of a tunable Copeland high D whistle measured at the exit of the windway is 17.2 mm. The lower end of the tube is OD 12.0 mm, with no indication of any flare. The sides of the windway are parallel and the head joint is cylindrical, extending 50 mm beyond the windway exit. Assuming a uniform wall thickness (except for the tuning slide socket), that means a 70% reduction over the length of the air column.

5

Ah, thanks for that reminder. I actually have a little data about Phil’s whistles from the discussion on Whistle Bores. Enough to suggest it would fall into the “Strongly tapered whistles, possibly (probably? inevitably?) with terminal flare.” I don’t know if it features the flare however.

I should perhaps elaborate on the flare. It’s a classic feature of conical flutes, Recorders and English flageolets and is used to pull the low end note up to the same pitch as its octave. The end note is unique in that it is perfectly vented - the hole diameter is the same as the bore diameter, whereas all other notes are less than perfectly vented. So if you adopt a certain amount of taper to sort out the imperfect venting on the 6 side holes, it will be too much compensation for the low note. The flare solves that.

6

The Calura/Eagle/Schoha (and similar) whistles have a pretty dramatic taper.

The ones I have here aren’t in D, so probably wouldn’t be a useful comparison, but the bell end of the lower ones, such as the B natural, is surprisingly narrow. I think it might be the sort of diameter one would expect from something like a very high F or G whistle.

Here’s a photo of one, to give a general idea. The whole thing is very narrow, but especially the bell end.

https://www.etsy.com/fi-en/listing/202267572/vintage-calura-flute-made-in-germany

7

Thanks for that, Steve and stringbed.

First to the flare, or lack thereof. I reckon it would be pretty hard to do a flare in a tapered metal tubing whistle, and it would probably look awful! I can’t remember ever seeing such a thing. Anyone?

And secondly, the degree of taper, 70%. This puts it between the Bold Taper and Flare grouping (Swayne, McGee Pic-whistle, Bleasley, 70-80%) and the Full Length Bold Taper group, the Clarkes, which reduce to 60%. But the taper is extended over more of the length (ie the cylindrical section is shorter) than on the Swayne etc group, and closer to the Clarkes which have virtually no cylindrical section. Do we now have 5 categories?

8

So would probably fall into the same category as I’ve bunged the Clarke’s. Full Length Bold Taper.

9

Sterling silver Copeland low d ~1" below ‘ears’ is 24mm od, base of tube 17mm od. Distance between measurements ~ 500mm. Blade to end 536mm.

These may be accurate because I am using an old caliper and a steel rule marked in mm.

[Edit: measurements the same on a brass low d]

10

Bleazey low d: inside tuning slide: 18mm id. bottom 12mm id.

11

Eeek, we haven’t conquered treble D, and Dr Phill is slamming us into Low D. Oh well…

Interesting (reassuring?) that the Copeland, at blade to bell of 536 is pretty much twice as long as Treble D whistles around 265. 536/265 = 2.02

But the diameters are not double. Hmmm, could the areas be double?

Low D top OD is 24mm. Let’s assume wall thickness of 0.3mm, so 24 - 0.6 = 23.4. Cross Sectional Area (CSA) = Pi * r2 = 430

Treble D top OD is 17.2. Minus 0.6 = 16.6. CSA = 216.

430/216 = 1.99. Hmmm, not far off 2!

And the end diam is about 70% of the top diameter.

The Bleazey Low D is smaller at 18 and 12 (IDs). But the reduction ratio comes in close at 67%.

12

I was answering Steve, mainly.



But I may not have the tuning slide in the correct place…

Especially with the limits of accuracy of my measurements - illegible calipers measured against a steel rule and rounded to nearest mm. 2 significant figures might be pushing it a little.

The Copeland does feel delicately slender - part of it’s aesthetic appeal. I never thought about relative proportions. But then I have never owned a Copeland high D.

The Bleazey has a flare at the end on the outside and inside. The inside flare is short enough (5mm? that my callipers were measuring (what I assume is) the narrowest point.

From observation I think that the Copeland is parallel bored until the tuning slide and then a constant taper. I suspect that the bore of the Bleazey is more complex.

13

Indeed, but if you do the maths with the slide at each extreme, it probably doesn’t change things that much. I should add I’m not proposing a firm rule here, just exploring what your numbers tell us.

Especially with the limits of accuracy of my measurements - illegible calipers measured against a steel rule and rounded to nearest mm. 2 significant figures might be pushing it a little.

Yeah, but if I’d rounded it any more I would simply have shown that 1+1 = 2! (Only works for fairly low values of 1.)

The Copeland > does > feel delicately slender - part of it’s aesthetic appeal. I never thought about relative proportions. But then I have never owned a Copeland high D.

Yeah, this is an area I’m trying to get to grips with (so to speak). For example, I definitely find the right hand end of the Clarke D whistles too thin. But I’m also finding the left hand end of my Abominable Pic-Whistle a bit fat. Not problematically, but noticeably. And it’s the thumb that’s noticing it, not the fingers. I’m sure I could reduce it if I decide to proceed along those lines, as the piccolo version it’s snitched from has to be thick enough there to allow for a socket and tenon joint to the barrel section. In a whistle version, I’d only need to accommodate a thin slide. Hmmm, which then raises the question, why don’t I do the same on the piccolo version? Hmmmm.

The Bleazey has a flare at the end on the outside and inside. The inside flare is short enough (5mm? that my callipers were measuring (what I assume is) the narrowest point.

Interesting. That sounds a bit short to be the classical terminal flare. More likely just a smoothing of the “bore to atmosphere interface”.

From observation I think that the Copeland is parallel bored until the tuning slide and then a constant taper. I suspect that the bore of the Bleazey is more complex.

If you were moved to explore further, you need to measure the bore diameter at each end and at a few points and along the way. Inserting cylindrical objects into each end, and then measuring how far they insert and their diameters is pretty easy. Ah, but where to find long cylindrical objects of varying diameters? Aha! Tin whistles! Now we know why they make them in so many sizes!

(Don’t rely on the one you’ve squashed in the car door after that fabulous session where the barman brought out the whiskey …)

14

Note the difference in the end diameter between an old Clarke D and a C.Mathieu D (Ré), another antique.

15

How about little disks, in say, 1mm dia increments, attached to chopsticks. Anyone have a lathe ?

(this approach may be difficult to use if there are are both convex+concave bore perturbations.

Also, there’s always this:

https://www.amazon.com/Pc-Precision-Telescoping-Gage-Set/dp/B00R5E5PI6

But, hey, maybe a little too formal.

16

How about little disks,

Craig Fisher used to have that sort of sets available, for measuring (uilleann) pipes. But that was twenty years ago.

17

Yes, the little discs idea has been around a long time. It has the slight downside that it always measures the minimum diameter, if the bore is out-of-round, but that’s not a knock-out blow. You can modify them to explore minimum and maximum diameters if you want by ruling a line across one diameter, and then sanding the wood edges on the sides, being careful not to sand the disc at the end of the lines.

I use telescoping gauges such as those shown in trill’s link. You need to extend the shaft to be able to explore deep into longer things.

18

Yeah, that looks a bit more robust.

The end of the Mathieu looks like it’s been sharpened. For self protection in rough sessions back in their day? Or sees extra duty pipping olives?