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PostPosted: Sun Aug 19, 2018 6:30 am 
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Matt NQ wrote:
Thanks Terry and Geoffrey for your most illuminating comments on the Fajardo wedge. Still interested myself as I don't have the tools or ability to make reamers (and I probably should disclose I'm setting out to make whistles not flutes). I'm curious about the "D-shaped" cross section after wedging that both of you have talked about (the pouring epoxy method you mention Geoffrey would produce a flat topped wedge and thus a D cross section). My understanding is that the normal Fajardo wedge is cut out of a hollow cylinder, which presents a curved with flat edges profile toward the embrouchure hole in a flute or the window of a whistle, not a D shape. I'm curious that you found the flat topped wedge (with the poured epoxy) worked best, Geoffrey, despite that it would seem logical that a flat topped wedge is further from a parabolic reaming and likely to create more "aerodynamic inelegance" than the curved with flat edges profile of a tapering wedge cut diagonally from a hollow cylinder? Or perhaps I've misunderstood something here? :)


Interesting, Matt. I've always assumed the Wedge to be a flat-faced wedge cut off a cylinder, but I'd be happy to be disabused. A quick look on Google shows us what Doug Tipple does:

Image

but I don't know if that's what Raoul Fajardo had in mind.

But even Doug's wedge presents issues to the circulatory air stream, doesn't it. Those flats either side of the central hollow.
What would be better would be a fully-hollow wedge-shaped segment of a cylinder, curved on the outside to meet the cylindrical bore, fully curved on the inside to smooth the flow of air. But it's surely all getting too hard. Easier to put in a well-greased former and pour in some potting compound, or simply ream the thing in the first place? Reamers are easy to make, or there's that chap in the village....

Great to hear you are planning to make whistles, incidentally. I've made one myself. One. Bit sad really, eh? I have some thoughts on a second....


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PostPosted: Sun Aug 19, 2018 7:40 am 
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Matt NQ wrote:
Terry McGee wrote:
For those unfamiliar with the Fajardo wedge, it's a wedge cut out of a cylinder, inserted into the top end of the flute head...
But, consider a cross-section cut through at the embouchure hole. The bore won't be round, it will be D-shaped. And remember our flute is side-blown, so the top end of the vibrating air column has some spiral elements. I'm guessing that our D-shaped bore is introducing some aerodynamic inelegance.

Thanks Terry and Geoffrey for your most illuminating comments on the Fajardo wedge. Still interested myself as I don't have the tools or ability to make reamers (and I probably should disclose I'm setting out to make whistles not flutes). I'm curious about the "D-shaped" cross section after wedging that both of you have talked about (the pouring epoxy method you mention Geoffrey would produce a flat topped wedge and thus a D cross section). My understanding is that the normal Fajardo wedge is cut out of a hollow cylinder, which presents a curved with flat edges profile toward the embrouchure hole in a flute or the window of a whistle, not a D shape. I'm curious that you found the flat topped wedge (with the poured epoxy) worked best, Geoffrey, despite that it would seem logical that a flat topped wedge is further from a parabolic reaming and likely to create more "aerodynamic inelegance" than the curved with flat edges profile of a tapering wedge cut diagonally from a hollow cylinder? Or perhaps I've misunderstood something here? :)


I've done variations on both types of wedges: the poured epoxy "flat topped" wedge as well as the type made from a section of tubing like the original patent version put out by Raoul Fajardo. I ended up doing the flat-topped epoxy version because I didn't perceive any noticeable difference between the two and it was easier to implement. That doesn't mean that there is no difference, and a better player might find differences that escaped my notice. But I didn't like the effect of either of them.

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PostPosted: Sun Aug 19, 2018 9:01 am 
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How about something like a hollow cone, possibly with a rounded rather than pointy tip, tapering to the nearly the full width of the bore? Or a truncated, lopped off tip? The cross-section would be circular, not a 'D' as with a wedge as has been discussed. I guess you need some way to place/adjust a stopper, particularly if a flat disk stopper end is a requirement to manage the air stream. Or, hey, a flat disk at the point of the cone, and the whole cone moves to adjust the length of the air column (moving the taper along as well).

Image

Image

Image

Yes, that's a bullet, but I can't draw, and tried to find something to visualize the shape. Imagine this being hollow.

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PostPosted: Sun Aug 19, 2018 9:12 am 
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Terry McGee wrote:
Forgive me if we've been here before (I am old enough to have a Papal Dispensation to pull this concession!), but tell (or remind!) me what the philosophic basis of your app is. Does it derive from Paul Dickens' work at UNSW, based on their acoustic impedance spectrometer, or drawn from some other source?
The Bibliography lists the sources for our modelling algorithms. The tonehole model, in particular, is the work of Antoine Lefebvre. For modelling the mouthpiece and the effect of the player, we took a somewhat different approach than Dickens. Rather than predicting a playing frequency directly, we predict the minimum and maximum frequencies at which a note will sound, on the assumption that these bounds are less dependent on the player (at least for whistles). "To predict the nominal playing frequency, the whistle model assumes that you will steadily increase the air velocity in the windway as you go from the lowest note on the instrument to the highest."


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PostPosted: Sun Aug 19, 2018 9:27 am 
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Matt NQ wrote:
Thanks Terry and Geoffrey for your most illuminating comments on the Fajardo wedge. Still interested myself as I don't have the tools or ability to make reamers (and I probably should disclose I'm setting out to make whistles not flutes).
I've made cylindrical-bore whistles with a wedge under the window. To form the wedge, I carved a tail into the bottom of the fipple block extending a cm or two down the tube. The top of the tail is flat, the bottom is curved to match the inside diameter of the tube. The wedge does help balance the tuning of the octaves, to a limited extent, so it is worth trying out. If the tail is too big, big enough to really bring the octave tuning in line, it starts to interfere with the tone of the whistle. I haven't done enough experimentation to work out the best compromise.


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PostPosted: Sun Aug 19, 2018 11:29 am 
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I've always assumed the Wedge to be a flat-faced wedge cut off a cylinder, but I'd be happy to be disabused. A quick look on Google shows us what Doug Tipple does:
but I don't know if that's what Raoul Fajardo had in mind.
But even Doug's wedge presents issues to the circulatory air stream, doesn't it. Those flats either side of the central hollow.
What would be better would be a fully-hollow wedge-shaped segment of a cylinder, curved on the outside to meet the cylindrical bore, fully curved on the inside to smooth the flow of air. But it's surely all getting too hard. Easier to put in a well-greased former and pour in some potting compound, or simply ream the thing in the first place? Reamers are easy to make, or there's that chap in the village....


Yes, it does get too hard to fuss so much! I made wedges like the one pictured on Doug's website, only I took the trouble to remove the flat top by "blending" the inner curve of the hollow wedge so that it matched the curvature of the flute bore more elegantly. My assessment is that it's a pain in the neck without any profound difference in performance. If one is going to fuss to that degree, it truly is easier to make (or have made) a reamer. Though the poured epoxy idea you had would be a great in-between solution (probably fairly easy to implement with some practice). I've done a lot of work with mold-making and casting in pursuit of some highly experimental cast-bore xiao (long, long story), and there is a lot of potential in casting portions of a flute bore to affect some acoustic change. But I'll also add that it's a messy process and one needs a pretty good motivation (commercially) to take that approach. Your mileage may vary. I spent thousands of dollars and dozens of hours of R&D trying to master aspects of mold-making/casting, and while it was highly educational, in the end I'd opt out in most cases where there might be another solution.

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PostPosted: Mon Aug 20, 2018 9:30 am 
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Here's another question based on the original question.

What are your thoughts on the differences between straight cone bores and complex cone bores?

In references to the musical aspect rather than manufacturing.

Thank,

Tommy

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PostPosted: Mon Aug 20, 2018 10:17 am 
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tompipes wrote:
Here's another question based on the original question.

What are your thoughts on the differences between straight cone bores and complex cone bores?

In references to the musical aspect rather than manufacturing.

Thank,

Tommy


I'm far from being an expert on the mathematical part of woodwind design, but there is certainly a difference. When I made my very first Irish flute, I had to manufacture a reamer. This was years ago, and I was working from some blueprints that I got from Terry McGee (a Pratten flute). When I set about making the reamer, I noticed that the variations in the bore measurements did not create a straight taper. However, the perturbations were very subtle, and in my ignorance I assumed that it resulted from either shrinkage of the original bore or simply human error in measuring the bore. So to save time and hassle, I just smoothed them out and made a straight taper.

The results were good. The flutes sounded just fine and a few more experienced players tried them and said "These are good!". No one said "These are great!". When I began working with Jon Walpole (aka Paddler) he was the first person to say, "These tiny perturbations are really important". So I made new reamers that included the tiny irregularities that I had smoothed out of the first version. There was a noticeable improvement. It took the flute "to the next level" if you will, and with a few more tweaks here and there, finally resulted in the "These are great!" reaction that I was going for.

So clearly these things matter.

Just as a matter of interest, speaking of the effects of bore manipulation, I'll share a bit.

I did a project last year where I attempted to create an "optimized" xiao (Chinese end-blown flute). A researcher at the University of British Columbia who was a xiao enthusiast did his master's thesis on the xiao and his attempt to take the traditional folk design (which is a cylindrical bore instrument) and improve it's harmonic balance and tuning.

His research and process was very impressive, involving complex mathematical models and sophisticated microphone arrays for measuring acoustical impedance, etc.. In the end, he succeeded. But the nature of his success was totally outside of the box.

He created a flute whose bore was neither conical nor cylindrical. It was, in fact, totally unlike anything anyone has done before (to my knowledge). The inner bore resembled a couple of sine waves running in parallel. Or to use a more earthy description, the bore resembled a snake that had swallowed a series of rodents, causing it to bulge out in places along it's length!

This was a flute that was impossible to manufacture using conventional means, since it could not be bored our reamed. In the end, I decided to make this flute (another collaborator had gotten the specs directly from the researcher and had gotten me permission to use them). This was what I referred to earlier when I spoke of mold making and casting, because the only way to make this flute bore was to cast it from resin. This is because I wanted the outside of the flute to be wood, you understand. I suspect someone could use a 3D printer to make the flute if they don't mind a plastic flute. However, I won't go into what a long, difficult and messy process this was (it involved casting wax mandrels that could be melted out after the resin had cured, etc.). But it made me appreciate the trial and error that went into perfecting the bore profiles of early flutes from the Baroque period forward. I'm told that they did a lot of modification of bore profiles, including "chambering" in places to optimize the tuning and harmonics.

In the case of this optimized xiao, the researcher succeeded beautifully. The tuning balance was excellent--easier to achieve than on the conventional design. And the harmonic spectrum of the instrument was also balanced, giving it a uniformly strong and reedy tone. But here's the surprise that came at the end of it: xiao players didn't really like it! The xiao as a folk instrument has a characteristic timbre and certain idiosyncrasies that make it what it is, and the music it is used for has evolved along with it over centuries. This man had engineered the character right out of the flute! So he improved it on one hand, and erased it's identity on the other hand.

I made a few prototypes of this flute, and they are really cool. Insanely difficult to make, and I spent a ton of time and energy only to discover that the Chinese, in their wisdom, had already made an amazing flute that did not require any improvement or optimization at all. They had worked out all of the bugs in the last couple of millennia, and had created a flute with a unique character. Changing that was not an improvement. It merely made something that was different.

I think the silver flute is basically an "optimized" orchestral instrument that was an improvement (in some ways) over the wooden, conical bore instruments of the time. But it also lost a lot of the character of it's predecessors.

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PostPosted: Mon Aug 20, 2018 10:53 am 
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I make Uilleann pipes, and the appropriate reamers too, I'm aware of the importance of the tiny humps and bumps in a bore.

I kinda remember reading that some makers of the Pratten style flute used a straight taper in most of the bore. I mean from the head joint to the foot joint.

Could this be true?


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PostPosted: Mon Aug 20, 2018 7:28 pm 
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Can somebody clarify about these bore perturbations? Are they just places with no taper (or less taper)? Or are they more involved?


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PostPosted: Mon Aug 20, 2018 8:03 pm 
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Can somebody clarify about these bore perturbations? Are they just places with no taper (or less taper)? Or are they more involved?


The degree of taper varies at different points along the bore. Some sections may have no taper at all, and occasionally the bore becomes wider for a while before continuing to taper towards the foot. This latter situation is referred to as chambering. I've profiled a lot of different antique and modern flute bores, and have yet to find a simple straight taper. I can usually figure out how the maker achieved the effect, either by using a single irregular reamer, or by using multiple different reamers in sequence, or, in the case of chambering, by back-reaming at one or more joints or at the foot, sometimes using the same reamer that was used to create a different part of the taper from the head end.


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PostPosted: Tue Aug 21, 2018 6:54 am 
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paddler wrote:
Quote:
Can somebody clarify about these bore perturbations? Are they just places with no taper (or less taper)? Or are they more involved?


The degree of taper varies at different points along the bore. Some sections may have no taper at all, and occasionally the bore becomes wider for a while before continuing to taper towards the foot. This latter situation is referred to as chambering. I've profiled a lot of different antique and modern flute bores, and have yet to find a simple straight taper. I can usually figure out how the maker achieved the effect, either by using a single irregular reamer, or by using multiple different reamers in sequence, or, in the case of chambering, by back-reaming at one or more joints or at the foot, sometimes using the same reamer that was used to create a different part of the taper from the head end.


Now, just one word of caution here (without otherwise disagreeing with your findings). My study on bore compression by over-tight thread wrapping makes it very clear that bore compression is a very real issue. So we have to be very careful in interpreting bore measurements around the tenons and a little each way of them. I suspect a lot of what people have interpreted as "chambering" is the result of bore compression. Given the mass of evidence I have assembled, coupled with the obvious difficulty in creating a "chambered" bore, I would suggest the onus is on chambering proponents to prove what they see is chambering and not just compression.

Of course, the ultimate proof is in the pudding. If a "chambered" flute is more in tune, more vibrant than a more simply-tapered flute, we will flock to your door....


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PostPosted: Tue Aug 21, 2018 7:40 pm 
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I agree that compression of the bore by thread-wrapping effects could lead to a bore that has the chambering characteristic I described, close to a joint between two sections. In fact, I have seen plenty of examples of this. However, I think there are some ways to distinguish between this effect and chambering that was done deliberately by back-reaming. If thread-wrapping has constricted the bore it would show up as an increase in the degree of taper (i.e., a constriction), followed by a decrease (i.e., an apparent cavity), as we travel down the bore towards the foot. (Here I am assuming a discussion of the joint between left and right hand sections, or between right hand and foot sections, of a flute, not between head and left hand section.) The location of the constriction would coincide with the location of the tenon, under and adjacent to the thread wrapping. When chambering is introduced deliberately by a maker it would be done by back reaming (inserting the reamer at the lower end of a section in order to enlarge the bore there). In this case, it would show up as a decrease in the degree of taper (i.e., a cavity), followed by an increase, as we travel down the bore towards the foot. The location of the cavity would coincide with the location of the tenon. In other words, the cross sectional area of the bore would be increased, not decreased, in the location of the thread-wrapped tenon.

So, I agree that we have to look carefully at the precise location of the cavities in the bore before drawing any conclusions. I have seen examples of both cases. I have heard of, but not personally observed, any deliberate cavitation in a bore that does not coincide with the end of a section. I believe Rod Cameron used to do some of this latter type of cavitation when trying to replicate original baroque flute bores. He would do it by using flaps of sand paper on the end of a rod driven by a power drill, and would be careful to insert the rod a precise distance before starting. I imagine that this would take a significant number of sand, clean, measure (or test) iterations to get right. I'm not sure of the location of the cavities or if those flutes had suffered thread compression issues. It is worth noting, though, that this kind cavitation approach can be used to address specific tuning anomalies on an flute where you no longer want to change a tone hole location, size or degree of undercut. It seems like a way to treat a specific, individual instrument, after the fact, but it seems to me that it would be tricky to replicate accurately, especially in mass production.

The most common and obvious uses of back reaming seems to occur in the foot section of 6 key flutes. I've seen many examples of this. In some cases its clear that the maker didn't use a separate reamer, but rather just reinserted the reamer that created the original tapered bore from the opposite end. You can tell this by the symmetrical shape of the tapers in the bore and cavity. This is easy to do, even in mass production.


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PostPosted: Tue Aug 21, 2018 8:41 pm 
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A pipemaker once told me of some old chanters that had two constrictions in the bore, one approx 1/3 from the top, and the other 1/3 from the bottom (very roughly, i can't recall the conversation perfectly). These constrictions were such that a reamer wouldn't be able to create such a bore. His theory, and possibly of other pipemakers, was that banding while soaking (or possibly while green) was done deliberately in conjunction with boring/reaming to create those constrictions. My gut tells me that such a thing was not mainstream practice, if it existed at all. In fact, I'm not sure if any of this is true, but it's worth a bit of a daydream though.


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PostPosted: Wed Aug 22, 2018 5:15 am 
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Tunborough wrote:
Matt NQ wrote:
Thanks Terry and Geoffrey for your most illuminating comments on the Fajardo wedge. Still interested myself as I don't have the tools or ability to make reamers (and I probably should disclose I'm setting out to make whistles not flutes).
I've made cylindrical-bore whistles with a wedge under the window. To form the wedge, I carved a tail into the bottom of the fipple block extending a cm or two down the tube. The top of the tail is flat, the bottom is curved to match the inside diameter of the tube. The wedge does help balance the tuning of the octaves, to a limited extent, so it is worth trying out. If the tail is too big, big enough to really bring the octave tuning in line, it starts to interfere with the tone of the whistle. I haven't done enough experimentation to work out the best compromise.


Now it would seem reasonable to guess that a wedge wouldn't present an aerodynamic problem in a whistle. As the whistle is endblown rather than sideblown (allegedly for our protection), there won't be any rotation of the vibrating air column.

Just tried dropping a bamboo kebab skewer down an upturned whistle and played it. No massive effect. It kills a flute.

(There is a line of thinking that flute making would never have reached its current heights without benefit of kebab skewers. An alternate like of thinking recognises that kebabs would not have reached their current level of ubiquity without the assistance of flute makers. It is possible that truth lies between these two extremes....)


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