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PostPosted: Mon Dec 03, 2018 4:22 pm 
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Hi,
On various online discussions (and I also believe on the website of a flute makers, but I am not sure who it was) I have read the generalisation that Rudall and Rose flutes have a more "complex" bore than typical Pratten flutes. Could someone explain to me, what that means?
So far I only had the thump rule in mind, that Pratten style flutes have a bigger bore and bigger holes than typical R&R flutes..

Thanks for your input :)


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PostPosted: Mon Dec 03, 2018 6:43 pm 
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This might get you started, ertwert. It illustrates the bores of a number of 19th century flutes. A Prattens and Rudall & Rose No 5501 are among them.

Image

The discussion around it is at: http://www.mcgee-flutes.com/bores.htm

But you immediately run into the problem of knowing what was original, and what is the subject of subsequent wear and tear. Note at the top left of the graph that some of the flutes show horizontal shelves or other bumps and grinds, while others are pretty much straight cones. Further down the flutes, particularly where the body meets the foot, we again see some strange anomalies. Some have taken these complications literally, swear by them and incorporate them in their own versions; I'd argue these days that they are the result of strangulation by their threaded tenons.

I guess we won't really know until somebody cold-bloodedly makes a flute with all the bumps and grinds, and another without them, and we get to compare the difference....

Unless, you out there Tunborough? Could WIdesigner tell us what differences to expect if we say took the Nicholson's flute bore above (in green) and straightened it out into a plain cone starting at 19mm and picking up the main slope around 100mm along. We could then look at the tuning anomalies of that flute and see if the change would be likely to cure any of them.


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PostPosted: Tue Dec 04, 2018 5:58 am 
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Hi Terry,

Tell us more about WIDesigner. It is good and/or useful for Irish flute design work? Any use for PVC piping type flute design?


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PostPosted: Tue Dec 04, 2018 3:54 pm 
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Terry McGee wrote:
Unless, you out there Tunborough? Could WIdesigner tell us what differences to expect if we say took the Nicholson's flute bore above (in green) and straightened it out into a plain cone starting at 19mm and picking up the main slope around 100mm along. We could then look at the tuning anomalies of that flute and see if the change would be likely to cure any of them.
Yes, in principle, it could. It would take a lot of data entry (and some approximation) to capture all the bumps and grinds: to describe the bore, you have to give the bore diameter at every point where the taper changes, along with all the other details about the instrument geometry. If you can provide the numbers, I can run them through WIDesigner, or you can give it a try yourself. I've tried a similar exercise on a historical shawm.

As yet, WIDesigner doesn't handle keyed toneholes; notes with open keyed toneholes may be flatter than WIDesigner would predict. For the purposes of this exercise, though, it can at least tell us about changes in tuning.

The other thing WIDesigner can't help with yet is tone colour. Some may argue that the bumps and grinds are there to adjust the tone colour, not the tuning.

Funny this should come up now. I was just about to ask you: Do you have anything further to relate tone colour to harmonic strength since you wrote http://www.mcgee-flutes.com/Flutetone-Analysing_an_existing_tune.htm? I've been asked to see if WIDesigner's note spectrum graphs can tell us anything about timbre.


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PostPosted: Tue Dec 04, 2018 4:03 pm 
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Andro wrote:
Tell us more about WIDesigner. It is good and/or useful for Irish flute design work? Any use for PVC piping type flute design?
The answer is a qualified (and biased), "Yes." See https://github.com/edwardkort/WWIDesigner/wiki, and https://github.com/edwardkort/WWIDesigner/wiki/Working-with-the-Flute-Study-Model. However, the transverse flute model requires more data from real flutes for proper calibration, and none of the current contributors has the flute skills to collect this data. Let me know if you'd like to help us collect geometry and tuning data from real flutes.


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PostPosted: Tue Dec 04, 2018 7:19 pm 
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Tunborough wrote:
Terry McGee wrote:
Unless, you out there Tunborough? Could WIdesigner tell us what differences to expect if we say took the Nicholson's flute bore above (in green) and straightened it out into a plain cone starting at 19mm and picking up the main slope around 100mm along. We could then look at the tuning anomalies of that flute and see if the change would be likely to cure any of them.
Yes, in principle, it could. It would take a lot of data entry (and some approximation) to capture all the bumps and grinds: to describe the bore, you have to give the bore diameter at every point where the taper changes, along with all the other details about the instrument geometry. If you can provide the numbers, I can run them through WIDesigner, or you can give it a try yourself. I've tried a similar exercise on a historical shawm.

As yet, WIDesigner doesn't handle keyed toneholes; notes with open keyed toneholes may be flatter than WIDesigner would predict. For the purposes of this exercise, though, it can at least tell us about changes in tuning.

OK, I don't think they're knock-out blows. How about I come back with the simplest set of dimensions that I think will be enough to alert us to the effect of the compression at the top of the LH section. You enter them (you'll be much quicker than I, and will probably get it right!), and get back to us all with the results. Then we can all pore over it and see whether we think it answers any questions, or just adds to our confusion!
Quote:
The other thing WIDesigner can't help with yet is tone colour. Some may argue that the bumps and grinds are there to adjust the tone colour, not the tuning.

How dare they mess around with tone colour before the crack tuning! (Unless of course they did crack tuning but something has happened to the flutes since to give the impression they haven't!)
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Funny this should come up now. I was just about to ask you: Do you have anything further to relate tone colour to harmonic strength since you wrote http://www.mcgee-flutes.com/Flutetone-Analysing_an_existing_tune.htm? I've been asked to see if WIDesigner's note spectrum graphs can tell us anything about timbre.

No, I don't think so. Been too busy! But always happy to discuss if you have specific issues or ideas you want to bounce.


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PostPosted: Tue Dec 04, 2018 9:14 pm 
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Tunborough wrote:
Andro wrote:
Tell us more about WIDesigner. It is good and/or useful for Irish flute design work? Any use for PVC piping type flute design?
The answer is a qualified (and biased), "Yes." See https://github.com/edwardkort/WWIDesigner/wiki, and https://github.com/edwardkort/WWIDesigner/wiki/Working-with-the-Flute-Study-Model. However, the transverse flute model requires more data from real flutes for proper calibration, and none of the current contributors has the flute skills to collect this data. Let me know if you'd like to help us collect geometry and tuning data from real flutes.

Let's see how the simple experiment (mooted above) with straight and compressed bores goes. If that shows promise, let's follow up with some real flute measurements and calibration data. Or pause to find out what's not working.

Developing our models from originals was a great way to start the revival, but we really do need to bite the bullet and lash out on our own. It would be great to partner a viable modelling system with 3D printing prototype making. And of course Reel Time Tuning Analysis and maybe an artificial blowing system to take human our variability out of the equation. Hmmm, put those various technologies under the control of an AI and the rest of us can slip down the pub for a few tunes while they optimise our future for us!

They can call UBER and join us at the pub when they've got something worth showing....


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PostPosted: Tue Dec 04, 2018 11:00 pm 
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So, Tunborough, let's see if I have enough data for your system to play with.

Calling the junction between the cylindrical head and the conical body our 0 reference point:
Stopper face at -172 (i.e. 172mm back from junction)
Embouchure hole at -153, oval: 12.2 long x 10.1 wide
Finger holes at, diameter:
87, 7mm
122, 10mm
156, 7.2mm
217, 9.2mm
248, 10.6mm
283, 6.1mm
Foot holes:
375, 12.3mm
410, 8.9mm
End 446mm

Head bore 19mm both ends
Top of conical body 19mm
Bore at 405mm 10.7mm
Bore at 430mm 10.7mm
Bore at end of foot (446mm) 11.35mm

All the above holds for both flutes excepting in Compressed Flute:
Top of conical body 17.7mm
at 50mm, 17.7mm
at 150mm, 16mm

I'm expecting the Compressed Flute to play pretty well at A440, excepting the D note will be painfully flat.

Assuming we get something like that, what differences does the Uncompressed Flute show?


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PostPosted: Tue Dec 04, 2018 11:11 pm 
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Two additional thoughts:

I'm imagining if you enter all that data as given, your flute model will be sharp, unless you already make an assumption about the degree of embouchure shading the average player (can we get his or her name - it would be handy to have them available in the lab!) does. If you don't make such an assumption, you could reduce the embouchure hole size until the A comes in at around 440Hz. I measured the embouchure location with the slide set to give that.

The two holes on the foot have pewter plugs dangling over them, so are effectively smaller than shown. But I can take the plugs off for pitch measurements.


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PostPosted: Fri Dec 07, 2018 8:41 pm 
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Terry McGee wrote:
So, Tunborough, let's see if I have enough data for your system to play with.
Almost.

We need the thickness at each tone hole, including those in the foot joint, and at the embouchure hole.
I'd like the outside diameter at the foot, although it doesn't make a whole lot of difference.
Is -153 mm the position of the centre of the embouchure hole?
How can the diameter of the first foot tonehole be bigger than the bore diameter at that point?
On the compressed flute, is the open end of the headjoint still 19 mm, leaving a sudden step at the junction with the first body section?

So far, with a bunch of assumptions about other parameters, I've got A4 in tune on the compressed flute; D4 is 63 cents flat, F#4, C#5 and C#6 are about 40 cents flat. "Uncompressing" that tenon makes everything flatter, by 20 cents at A4 and 10 cents at D4. Where's the tuning slide? If I shorten the headjoint by 6 mm, A4 is in tune and D4 is 53 cents flat; F#4 is still 40 cents flat. (All this is relative to E.T. What temperament would you like me to use?

We might want to add more bore points to capture the real bore profile more accurately. Then I'll ask for more tuning information.


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PostPosted: Fri Dec 07, 2018 11:13 pm 
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Tunborough wrote:
We need the thickness at each tone hole, including those in the foot joint, and at the embouchure hole.
I'd like the outside diameter at the foot, although it doesn't make a whole lot of difference.


Take wall thicknesses everywhere as 4mm for the purposes of this experiment. The foot diameter is for flange effect?

Quote:
Is -153 mm the position of the centre of the embouchure hole?

Yep

Quote:
How can the diameter of the first foot tonehole be bigger than the bore diameter at that point?

When I look in there, I can see the walls sloping inwards. So, yes the side branch is bigger than the pipe!

Quote:
On the compressed flute, is the open end of the headjoint still 19 mm, leaving a sudden step at the junction with the first body section?

Correct. Doesn't seem like a good idea. On the Uncompressed flute, I've lined up the slope of the body to meet the bore of the head at 19mm.

This sudden reduction of bore at the start of the cone is very common, as you'll see from the bore graph further up. Indeed, it's very rare to see a flute that doesn't have it. So the question I'm hoping we can answer is whether it was intended by the maker, or is an artifact of aging, including tenon compression.

Quote:
So far, with a bunch of assumptions about other parameters, I've got A4 in tune on the compressed flute; D4 is 63 cents flat, F#4, C#5 and C#6 are about 40 cents flat. "Uncompressing" that tenon makes everything flatter, by 20 cents at A4 and 10 cents at D4. Where's the tuning slide? If I shorten the headjoint by 6 mm, A4 is in tune and D4 is 53 cents flat; F#4 is still 40 cents flat. (All this is relative to E.T. What temperament would you like me to use?


The tuning slide is 22mm open at A=440Hz, so there's plenty of room for sharpening! Indeed, with the slide fully closed, xxo ooo plays Bb which seems a bit much.

So, no other wild effects from "decompressing"? But while it nudges the low D slightly in the right direction, it doesn't explain the flat-footed-ness.

Stick with ET as we have found no clear evidence of other temperaments. The errors the flutes show far exceed the (mostly) small deviations temperaments would make.

So it sounds like your system is looking promising? The figures you quote are about right. (F# isn't quite that flat but I notice the hole is well undercut. Can we handle undercutting in the system? Measuring it accurately might be tricky.)

Quote:
We might want to add more bore points to capture the real bore profile more accurately. Then I'll ask for more tuning information.


OK. Are you entering into new territory here, or have you already done some conical flute measurements?


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PostPosted: Sat Dec 08, 2018 5:46 am 
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These technical discussions are boring at times.

My mind is elsewhere at 3:34AM as I write this. Am composing two short operas (seriously) and woke up singing and conducting to an imaginary orchestra and chorus the overture and grande choral opening of one of them. I compose in my head and then sketch it on paper for later fleshing out and scoring. I've been told by people in the know that there is high demand for new American works that are easy to stage and sing and listenable. Both fit that criteria and both have great stories. I hope to be able to start pitching them come summer.

Am also stuffing marinated anchovies up my nostrils and taking selfies for the Tide Pool Challenge. Inspired by yesterday's articles of the endangered monk seals with eels stuffed up their nostrils. The monk seal folks liked my phrase, inspired by the late great Musette player and Baroque Flutist Jean-Christophe Maillard once "What the Phoque?!!!??"

Am about to embarked on a Rudall-bore project after the holidays when I take a break from relentless Folk Flute production. Am going to trust Robert Bigio's assessment that RR&C used straight reamers in combination and derive my bore using my recently acquired Nicholsonized #6716 (Not for sale - am keeping it everyone) that plays so fantastically. Am planning on developing a block mounted 8 keyed model using cast keys (pewter plugs on the low 2 keys) and making a bunch of these to sell in my retirement. That assumes that this one will copy well. My other R&C derived design is based on #6776 and is identical almost to the one Chris Norman uses, that formed the basis for copies by Rod Cameron, one of his former assistants and Chris Norman who is now making copies after apprenticing from Rod. These larger bored later flutes work better for me copying-wise than the 18545-1855 vintage R&R flutes.

Casey

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PostPosted: Sat Dec 08, 2018 11:00 am 
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If you're thinking of trying some experiments and need someone to put them through their paces, I wouldn't be adverse to taking a trip back across the water some weekend. I always enjoy visiting your workshop, Casey, and I'd love to know more about the technical details involved in the engineering of flutes!


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PostPosted: Sat Dec 08, 2018 1:36 pm 
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I suspect some people may have got lost in the details of the above discussion, but I just wanted to
point out that what Terry and Tunborough are trying to do here is actually very interesting (to me) and
potentially very valuable to many in the long term.

If they can show that a computer model is able to accurately predict the precise tuning characteristics
of an existing flute, when given a set of physical measurements, and if they are then able to show that such
predictions are reproducible for other flutes, then they will ultimately be able to propose answers, with some
confidence, to various longstanding and critical questions faced by flute makers.

Specifically, they will be able to answer questions about whether, and to what extent, various bore
perturbations actually affect tuning and tone, and what impact processes such as bore constriction, shrinkage, etc
have in practice. I think such questions are very much in line with the original post in this thread.

It is already possible to answer such questions, but only via the extremely laborious and time consuming process
of making new sets of reamers, and new flutes based on them, to test every hypothesis. The amount of work involved
in each such step is so enormous that we never really have the time or energy to get to the bottom of most of
the interesting questions. Consequently, we remain in this state of not really knowing whether a particular
feature of an existing (usually antique) flute's design was intentional, accidental, or the result of wear and tear or
damage. We have lots of theories, but few, if any, are ever really proven convincingly.

We also don't know whether certain kinds of wear, tear and damage, even if they are known to occur, are consequential
to the performance of a flute or not, or whether they account for other known anomalies. So, this line of exploration,
if it works, could be beneficial to anyone with a long term interest in understanding how to systematically improve flute
designs, and also to all those who would appreciate playing better instruments in the future.

Of course, it may turn out that the approach won't work with sufficient precision, perhaps because certain critical
physical mechanisms are not being modeled at all, or are being modeled with insufficient resolution. Nevertheless, I
think it is an interesting approach, and actually quite promising. Things like this always take a lot of work and time
to iron out all the problems though, so they require patience.


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PostPosted: Sat Dec 08, 2018 5:13 pm 
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MadMan, Weekdays preferred for visits. I prefer to take my weekends off, like everyone else.

I might be busy later this month on the last 2 Saturdays with a friend in the workshop - we are makig a pair of Pastoral Pipes based on an old Kenna pastoral pipe that showed up here in Kingston a decade or so ago. You could maybe stop by then. Otherwise not until the mid to late Spring.

Casey

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http://www.caseyburnsflutes.com
http://www.folkflutes.com


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