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 Post subject: Re: Rockstro
PostPosted: Tue Feb 18, 2020 6:52 pm 
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I don't know that it would provide anything relevant to figuring out why/how the R&R flutes came to exhibit this chambering effect, but for my part I'm tempted to try to replicate it, just to see what happens. My own Pratten design has been described by some as being a bit closer to an R&R than a true Pratten, and though it is keyless (which changes things) it might be fun to simply back-ream at the joints and see what happens. I make them with a two-piece body option, so I could make two flutes, back-ream them slightly at the joints and play them side-by-side.

Of course this is not apples-to-apples. Not apples to oranges, necessarily. Perhaps apples to crab apples? I don't know...

I'll check the data points on my reamer and see how closely they parallel the R&R. If somewhere in the ballpark, I can try to get the joints in roughly the same place and then try this chambering caper.

Again, this is just for fun because without replicating the R&R bore accurately and accounting for the effects of the keyed holes on the R&R, it's not like I'm going to suddenly figure out exactly what they were up to, if anything. It won't be a true comparison, but it might yield some surprise that would be worthy of throwing into the discussion, taking this out of the theoretical into the practical. I don't have to get fancy with the flutes, and I can use the same head on each one, to make it easier.

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 Post subject: Re: Rockstro
PostPosted: Thu Feb 20, 2020 2:36 am 
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I think if you look at the tenons on an example of one of your flutes, you'd see you can't afford to ream much out without weakening the tenon significantly. I would also suggest that, given that restriction, any variation in performance between the two flutes will be masked by the inevitable variations of embouchure cut, etc (unless you've highly automated all such sensitive operations).

I'm very aware I'm dragging the chain on coming back with my thoughts on Paddler's supplied data. There's a lot still happening around here post the fires, and my time hasn't been my own. I'll try to make some progress.


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 Post subject: Re: Rockstro
PostPosted: Thu Feb 20, 2020 3:36 am 
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OK, here's a tentative start:

1. You'll remember that I was concerned above that the graph as drawn didn't fully reflect the reality. I think if we are to draw conclusions from the shape of the bore, we need to make sure the bore graph is right.

2. Before we can draw any conclusions about what was originally intended, we need to agree on subsequent distortions. This may not be easy!

I haven't had enough quality time to come to conclusions, but here's what I've done so far:

1. I've redrawn the bore to get rid of any known errors (Paddler, alert me if I haven't got that right!)

2. I've added a little bit of head bore, running off to the left between 0 and -50mm. I think that it's important that we consider both the conical and cylindrical sections of bore and their relationship.

3. I've added clear indication of where each section starts and stops. These are the vertical lines at 0, 208 and 323mm along the X-axis.

4. I've indicated approximately where the outside of the tenons lie. These are the three sloping lines shown above the bore, starting at the three vertical lines. Remembering that tenon thread wrapping presents the major probable source of bore distortion, these indicators invite us to look at the bore below and near them and discount what we think might be later distortion. I think we see possible signs of compression inside all three tenons, indeed, it's unlikely that we would not.

At this point, it would be interesting to hear what people think might be other forms of identifiable distortions?

5. You'll see I've also put in place an "Intended?" trace (red, dashed), and another, not yet shown, "Column G". These enable us to easily test hypotheses by plugging in suggested dimensions.

Image

Don't pay too much attention to the red dashed "Intended?" trace except to note these points:

1. You'll see I've started the bore at x=0 at 18.6mm rather than the 18.3mm indicated in Paddler's data. That's because I reckon the 18.3 is caused by bore compression. Most RR flutes I've measured start around 18.6. But even so, I wonder if that is also a sign of bore compression. Why wouldn't they start at the head diameter (about 19mm)?

2. You'll see I've accepted that the bore at the foot has a short parallel section at the far end. Back reamed or at least parallel bore feet seem pretty universal, going way back to Baroque times. It's needed to pull the bottom note up to the same pitch as its octave.

You can have a play with looking for bore distortions and signs of alleged chambering by holding sheets of paper up to the screen.

If anyone wants a copy of the spreadsheet I've used to generate this image, just email me at terry@mcgee-flutes.com and I'll shoot it to you. You'll quickly work out how to add <my crazy interpretation> by entering a few data points. You can then export the image. You will need a location to send the image to be able to call on it here.

Thinking caps on, everybody....


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 Post subject: Re: Rockstro
PostPosted: Thu Feb 20, 2020 5:30 am 
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Now, above I said, of the bore: "Why wouldn't they start at the head diameter (about 19mm)?" This might seem a bold suggestion, but consider the bores below:

Image

The top group of three closely-clustered bores are from a stupendously beautiful and well-preserved Richard Potter flute in the Bate Collection at Oxford. The flute had no tuning slide, but three "corps de rechange" - alternative LH joints for different pitches. You can see just a smidge of bore compression. Note that the bores start from the full head diameter.

The light-green bore is a William Henry Potter flute of mine. The yellow bore is of the highly compressed Richard Potter flute also in my possession. Both are later flutes, but both suffer from obvious serious bore compression at all three tenons. These flutes have tuning slides, and are much slimmer, with dramatically thinner tenons more prone to compression. Note that they deviate not just at and around the tenons, but considerably further "inland".

We have to be able to "see beyond" these sometimes minor and sometimes massive distortions before we can form any views about alleged "chambering".

And keep in mind, we have only one historical reference to "chambering". It's totally vague and unsubstantiated. "Some of the flutes made by the old firm of Rudall and Rose were marvels of ingenuity in this respect." Only "some of the flutes"? Are the others boring and demonstrably worse in the tuning? And what is a "marvel of ingenuity" when expressed in millimetres?

Keep in mind the old reprobate who made the assertion has been proven to be a deliberate and serial misleader. (We have a stronger and more apposite expression in the Australian vernacular.)

I'd suggest we are in no position to discuss alleged chambering because we don't know what the bores originally looked like. We have to crack bore compression first.


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 Post subject: Re: Rockstro
PostPosted: Thu Feb 20, 2020 12:46 pm 
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I think your graph looks reasonable Terry, but notice how it now looks even more like the other Rudall graphs!

Your hypothesis that the tenons are compressed is also reasonable, but your arguments in this regard have always
been that compression causes the bore to get smaller, and you continue with this assertion here. I agree with that,
but in your new graph, and in all of the older R&R graphs the bore under the compressed tenon end is significantly
larger than the bore of the start of the next section, which has not been compressed. So if tenon compression had
occurred, which I believe it probably has to some extent, then the original flute would have exhibited an even larger
drop in bore size going from the tenon to the bore section downstream. This would make the chambers in the original
flute even larger than they appear on the graph today.

Also note that you can draw a reference datum line so high that it sits above almost every other point in the bore
profile, and yet still these peaks sit above it! What does that say to you?

Finally, look at the flare at the foot, which you quite happily agree is caused by back reaming (and again, I agree). It has
an almost identical shape and size to the flare at the tenon between the lower body section and the foot. It would seem
equally reasonable to suspect this had been formed by back reaming as well.

The tenon walls are all thick enough to support this level of chambering without weakness, and besides, any back-reaming
would have occurred prior to the tenon being cut, and so there would have been no danger of damaging the tenon during
construction.

Finally, note that none of your Potter graphs share these features (specifically, the peaks that represent chambers in
the bore of the assembled flute at the junctions). The compressed tenons always have a bore that is smaller underneath
them. This is the opposite of what is shown in the R&R bore graphs.

I think the evidence is overwhelming that some material was removed from the bore of R&R flutes at these two locations.
It could have been done deliberately, via back reaming, or it could have occurred as a consequence of some other aspect
of their manufacturing method. Either way, it occurs consistently, and with the same pattern, on all the R&R flutes we've
looked at, and on no others. Do you disagree with any of these statements? If so, please explain why.


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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 4:40 am 
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Paddler, I'm pretty sure we are all comfortable with the back reaming (or in some cases, parallel forming) of the tail end of the foot bore. I think the evidence is irrefutable, and the acoustics are readily provable and demonstrable.

But I can't in any way extend that to the tenons.

First of all, the logic defies me. What's to be gained? The location of joints in flutes are not dictated by acoustics, they are dictated by where you can possibly fit in a joint. Why would we believe that those points dictated by necessity would just happen to be points that we could subtly tweak for some so-far unidentified acoustical benefit?

Secondly, the scope is ludicrous. The most you could take away would be less than a millimetre, and the horizontal range of excision would be ten millimetres. Look at the vertical lines and the negative slopes above them in the graph. Keep in mind we are looking at a 40:1 exaggeration of the bore. The negative bore trends even at 40:1 are minor. In real life they are negligible.

Thirdly, tenon compression due to thread wrapping is a proven thing. It would easily explain those distortions.

Fourthly, the concept of "chambering" is the sole invention of a known and proven liar. Why should we pay him any heed when all his other assertions have been thoroughly debunked? See Welch, for example.

Fifthly, he doesn't link his alleged chambering with tenons, why should we?

And why should these distortions occur regularly and repeatedly? Because in the early classical (post-baroque) era, our flutes were made with very thin tenons with quite deep troughs wrapped with thread. It was a technical disaster. Earlier (baroque) flutes had thicker tenons and shallower troughs which could survive the distorting pressure. French flutes and later English flutes used cork, which exerted no pressure. Later flutes used African Blackwood, a timber much less prone to crushing than boxwood and cocus.

Now you haven't dealt with the startling differences in the baroque-style Potter in the Bate vs the two subsequent classical-era Potters in my possession. I think it tells us all we need to know. It didn't get crunched, despite being much older. I suspect the drawings do not reveal the thickness of the tenons under the thread trough - the chap who drew it, Australian Ken Williams, back in 1984, probably did not have permission to remove the thread. (Amusingly, I was there before him and several times after him, and I still haven't a clue who he is!)

There is work to be done here. But the first item of business is to totally understand bore compression. Once we can lay that ghost to rest, we can try to understand bores better. But when our view of these bores is so messed up, we can see nothing.


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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 11:56 am 
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Terry McGee wrote:
Paddler, I'm pretty sure we are all comfortable with the back reaming (or in some cases, parallel forming) of the tail end of the foot bore. I think the evidence is irrefutable, and the acoustics are readily provable and demonstrable.

But I can't in any way extend that to the tenons.

The data is the same for the bottom tenon and the foot. You can't simply discard the data because it disagrees with your pet theory.

Terry McGee wrote:
First of all, the logic defies me. What's to be gained?

That is for you to find out. The fact that you don't understand why something is there, is not a valid argument for claiming that it doesn't exist.
And even if you can prove that there is no acoustic benefit (which you have not yet done), you are still left with the possibility that these chambers
were caused by some other aspect of construction, such as wear as a result of some polishing method or work holding method, perhaps aimed at
reducing stress on the tenon when outside shaping was done. Anyway, the bottom line is that these flutes sounds like Rudall and Rose flutes, and
perhaps that was the aim. They have been one of the most desirable flutes to play for almost two centuries.

Terry McGee wrote:
The location of joints in flutes are not dictated by acoustics, they are dictated by where you can possibly fit in a joint. Why would we believe that those points dictated by necessity would just happen to be points that we could subtly tweak for some so-far unidentified acoustical benefit?

Yet again you ignore something I have already posted. There is some flexibility in the location of the joint, the length of tenon, etc. And the point is that this presents an opportunity to create a chamber consistently.
It doesn't allow you to place a chamber wherever you like, but it does present an opportunity for placing a chamber there, and guess what, when we measure these flutes they all have small chambers there. What the
benefit is, and whether the benefit is acoustical or not, remains to be discovered.

Terry McGee wrote:
Secondly, the scope is ludicrous. The most you could take away would be less than a millimetre, and the horizontal range of excision would be ten millimetres. Look at the vertical lines and the negative slopes above them in the graph. Keep in mind we are looking at a 40:1 exaggeration of the bore. The negative bore trends even at 40:1 are minor. In real life they are negligible.

This is similar in size to the flare at the foot, as the graph clearly shows, and you have not proven that the effect is negligible. In fact, you have claimed that it is not, at the foot.

Terry McGee wrote:
Thirdly, tenon compression due to thread wrapping is a proven thing. It would easily explain those distortions.

Wrong! There is zero evidence that thread compression causes the bore under a tenon to get larger. Again, you choose to ignore arguments that I have stated clearly and provided
ample data to support. Your claim that tenon compression could cause these chambers is completely unsupported by the data.

Terry McGee wrote:
Fourthly, the concept of "chambering" is the sole invention of a known and proven liar. Why should we pay him any heed when all his other assertions have been thoroughly debunked? See Welch, for example.

Wrong! Several people on this thread have stated that they have used chambering themselves. I have also used it myself. It is well documented in books and articles on flute making, and pipe making.
The fact that you don't understand it or use it yourself is not an argument that justifies calling others liars and claiming that it does not exist. The data of measured instruments and the theoretical
modeling of instruments both show that chambering is a real phenomenon. Furthermore, your own arguments are inconsistent. On the one hand you claim that thread compression is a terrible thing
since the bore perturbations it causes screws up the tuning of wooden flutes, but on the other hand you claim that bore perturbations in the form of chambers have no effect. And further, you claim that
the chambers are caused by the thread compression. I think it would be erring on the kind side to say that your logic in these arguments is nonsense.

Terry McGee wrote:
Fifthly, he doesn't link his alleged chambering with tenons, why should we?

I'm not claiming that these were definitely the chambers Rockstro was referring to. I'm claiming that (a) they exist, as evidenced by the measurements, (b) they exist at locations that would allow
consistent creation of chambers by well-known methods, and (c) that this is consistent with Rockstro's statement. In contrast, your claims are not supported by any evidence or any statements other than your own.

Terry McGee wrote:
And why should these distortions occur regularly and repeatedly? Because in the early classical (post-baroque) era, our flutes were made with very thin tenons with quite deep troughs wrapped with thread. It was a technical disaster. Earlier (baroque) flutes had thicker tenons and shallower troughs which could survive the distorting pressure. French flutes and later English flutes used cork, which exerted no pressure. Later flutes used African Blackwood, a timber much less prone to crushing than boxwood and cocus.

Again, Terry, you choose to ignore all the data that has been presented. They only occur regularly in Rudall and Rose flutes, not in all of the other flutes that use thread-wrapped tenons. Thereby immediately disproving your
claim that thread-wrapping tenons is the cause. The fact that they occur regularly and repeatedly in Rudall and Rose flutes indicates that they were caused systematically.

Terry McGee wrote:
Now you haven't dealt with the startling differences in the baroque-style Potter in the Bate vs the two subsequent classical-era Potters in my possession. I think it tells us all we need to know. It didn't get crunched, despite being much older. I suspect the drawings do not reveal the thickness of the tenons under the thread trough - the chap who drew it, Australian Ken Williams, back in 1984, probably did not have permission to remove the thread. (Amusingly, I was there before him and several times after him, and I still haven't a clue who he is!)

I don't see how this is in any way relevant. None of that data showed the bore getting larger as a result of compression. At best, your Potter graphs reinforce the claims that I have been making and disprove the theory that tenon compression caused the chambers.

Terry McGee wrote:
There is work to be done here. But the first item of business is to totally understand bore compression. Once we can lay that ghost to rest, we can try to understand bores better. But when our view of these bores is so messed up, we can see nothing.


We've already conclusively ruled out tenon compression as having anything to do with the formation of these chambers, so it is ridiculous to keep bringing it up over and over again. If it was the culprit we would see the same incidence of chambering in all other antique flutes as we do in Rudall and Rose flutes, and we do not. The data is overwhelmingly in favor of this not being due to tenon compression. Just for a moment, toss aside your pet theory and start looking objectively at the data.


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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 12:12 pm 
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Ok so can one of you guys with lathes and reamers make one and let us know? :)


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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 12:49 pm 
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PB+J wrote:
Ok so can one of you guys with lathes and reamers make one and let us know? :)


It's interesting enough that I would be tempted to try the experiment, but making reamers just to test it would be a big commitment ;-)

However, I think I could find time this Spring (just for my own interest and to see what happens) of applying this technique to my own flutes using the existing reamers that I have, which are probably pretty close to the R&R bores, the objective merely being to see if any effect (ideally positive) is achieved by creating those bore cavities.

I think that the diminutive size of the cavities is not an argument against them having an effect. I got my first conical bore flute blueprints from Terry of a Boosey Pratten from the 1860's. When I went to make the reamer (actually I hired a machinist to make the first one) I figured it would save time and money if it were just a straight taper. When I graphed out the bore specs, there were variations from a true straight taper that were so tiny I was convinced that they didn't matter. So I told the machinist to use the widest measurement and the narrowest measurement and to create a straight taper to run the distance between the points.

It made a very nice flute. But the feedback I was getting was just that: "nice". Not "wow!". Paddler convinced me that those tiny variations mattered, and many of them were very, very small. Perturbations on the order of .25mm or smaller in many cases. But collectively, by the time I added them in you couldn't really even see them, even if you sighted down the reamer! They were subtle. But they made a clear and obvious difference. When I made some new flutes with these reamers, all other factors being equal (embouchure cut, etc.) these flutes clearly stood out as being more lively, better harmonics, etc..

So tiny changes matter.

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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 1:15 pm 
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Okay, the language here is getting pretty heated among certain parties. If we can't avoid a tone of hostility (deny all you like; that's how it looks), the thread will have to see an unfortunate end. People can rein in the drama and aggression and still make their points quite lucidly.

It's up to you guys.

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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 1:20 pm 
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Nanohedron wrote:
Okay, the language here is getting pretty heated among certain parties. If we can't avoid a tone of hostility (deny all you like; that's how it looks), the thread will have to see an unfortunate end. People can rein in the drama and aggression and still make their points quite lucidly.

It's up to you guys.


I knew I shouldn't have said "diminutive". That's a size-ist attitude about bore cavities and it felt wrong when I wrote it...

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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 1:22 pm 
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Har har. :twisted:

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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 4:10 pm 
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It isn't so much as heated, as the same points are repeated. As a modestly-interested onlooker, It looks to me like the compression of the tenon Terry keeps coming back to would make the bore smaller, and that the measurements of the flutes presented by Paddler or Ellis actually show a bit of expansion. Terry at least has an explanation for compression, but doesn't address expansion. It is fair of him to ask if the data is correct.

As far as I can tell, we don't have any explanation of WHY there are expansions either from acoustics or artistics other than it seem typical of R&R flutes.

To take the conversation forward, I think it would be important to have SOME idea, or maybe just some postulated ideas about the acoustic effect. Intonation? Power? Certain notes? Certain registers?

I'm a mere intermediate-going-on-beginner, but the changes are probably subtle enough that you'd need to be a pretty good flute player to identify them.


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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 4:29 pm 
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tstermitz wrote:
It is fair of him to ask if the data is correct.

Naturally, this is true. How a question is asked is the issue, here. I have received complaints about this thread, and they are certainly valid. And I'm not singling out anyone.

tstermitz wrote:
I'm a mere intermediate-going-on-beginner ...

No, no - you need to go the other direction. :poke:

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 Post subject: Re: Rockstro
PostPosted: Fri Feb 21, 2020 4:50 pm 
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Once, long ago, we got into a brawl about pinky placement that resulted in the board's being shut down for two days. We are among the few people on Earth who share such interests. Cordiality, charity, good humor fit best, surely.


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