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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 4:20 am 
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Oh, and try eyeballing some flute bores. :poke:
You can often see chamfering and back-reaming - not as scientific as taking measurements, and sometimes rough patches in the wood texture can look rather like it, but it's a starting point.

On another aspect, I know for a fact that Chris Wilkes sometimes uses (tightly shrunk on and even lathe collet compressed) tenon end rings to minutely compress those points in the bore if, while voicing a flute, he feels he has opened up the bore too much there. I haven't discussed chambering with him as such, but I know it's something he looks for when examining a flute, and he once showed me the effect of putting a 4" nail (on a thin wire to move it) into the upper body bore of a flute with excessively sharp A and B and moving it around.

I also know empirically that, back when I was experimenting with tuning slides in my simple piccolos, I became very aware of the effects on tuning of either a bore expansion or a narrowing at the tuning slide (depending on size of brass tubing used) on the notes for which tuning slide location was at roughly half-way (principal node) along the sounding length of their fundamental - chiefly A and B! At piccolo size of course all effects are amplified. :swear: :boggle:

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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 5:59 am 
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jemtheflute wrote:
You can steam cocuswood with impunity. I've done it several times with intractable head cracks. (See my photo albums on Facebook). It softens easily and responds well. You just have to buff it up afterwards.


I'd have hoped so, but thanks for the confirmation, Jem.


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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 6:09 am 
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jemtheflute wrote:
...and he once showed me the effect of putting a 4" nail (on a thin wire to move it) into the upper body bore of a flute with excessively sharp A and B and moving it around.


Yeah, this is nicknamed "fishing". It is amusing, but having decided that a certain location of the 4" nail (or whatever) helps the notes in question, you then have to check every other note to make sure they are not badly affected! This is one of the scary issues with flutes (or any other woodwind). Everything is interconnected. Who invented these things? Have them brought to me!


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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 6:45 am 
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Paddler, for most of the peaks on the profiles graphed here, it looks to me that it would require use of a steeper reamer on both sides of a joint, not just back-reaming the upper segment. Am I reading the graphs correctly?


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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 11:37 am 
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Tunborough wrote:
Paddler, for most of the peaks on the profiles graphed here, it looks to me that it would require use of a steeper reamer on both sides of a joint, not just back-reaming the upper segment. Am I reading the graphs correctly?


I think you are interpreting the graphs correctly in the sense that the section of the reamer that does the cutting of the chamber would be steep,
in order to produce a localized chamber. The portion of the chamber that is upstream of the joint must be created by back reaming using a
separate, short, steep, reamer, but the portion of the chamber that is downstream of the joint can be created by the main reamer which is irregular
in shape. One way to view this is that the bore in the section of the flute that follows the peak of the chamber (which is at the joint itself) is
not chambered, so it can be created by normal reaming. The chamber only appears when the two flute sections are assembled together. Take a
look at the foot section of these flutes to see this clearly.

Just for contrast, and in case I have not made the point clearly enough earlier, take a look at the upper body section of Terry's tenon compressed
flute. This section has tenons at each end that have been squeezed. Technically speaking, this creates a large (non-localized) chamber in the bore
between these two squeeze points. It is a chamber according to the definition of chamber (a local maxima in the bore graph), but it is not localized
and not the kind of chamber that could be used for targeted tuning. It could not have been created by reaming or back reaming. It is not the type
of chamber I have been talking about, which is why I have used the terms localized, sharp, pointy etc and stressed that the chambers I'm talking
about are located at the tenons, not located separately from the tenons and caused by being trapped between tenons that have the bore constricted
underneath them


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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 1:11 pm 
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I strongly recommend that the participants in this thread read this article (you can sign up to JSTOR for a limited free readership): https://www.jstor.org/stable/25163825.

I seem to recall being told (not sure by whom or how long ago) that it was quite possible that all the body sections of a R&R flute were turned on a single tapering reamer, marked for how far onto it each should be pushed, and the foot end simply back-reamed with the tip of the same tool.

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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 1:48 pm 
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Thank you Jem. It has been lurking in my mind that this may be a case of ´tooling´ artifacts.

Bob

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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 1:50 pm 
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an seanduine wrote:
Thank you Jem. It has been lurking in my mind that this may be a case of ´tooling´ artifacts.

Bob


Can you clarify what you mean by tooling artifacts in this context?

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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 3:00 pm 
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jemtheflute wrote:
I strongly recommend that the participants in this thread read this article (you can sign up to JSTOR for a limited free readership): https://www.jstor.org/stable/25163825.

I seem to recall being told (not sure by whom or how long ago) that it was quite possible that all the body sections of a R&R flute were turned on a single tapering reamer, marked for how far onto it each should be pushed, and the foot end simply back-reamed with the tip of the same tool.


Thanks for posting that link Jem! I have read that article in the past, and again now just to make sure I had not missed anything. Would you agree with the following brief summary of it regarding the discussion in this thread?

1. Reamers have been in common use in flute making at least since the 17th century.
2. There is evidence that they are used to ream in both directions.
3. Regardless of the original intended shape of the reamer they do not actually measure perfectly straight nor cut a perfectly straight bore.
4. Reaming is done prior to other aspects of flute making, such as tone hole placement, tuning etc.
5. A consistent, repeating bore shape in a family of flutes is strong evidence of intentional shaping.

Basically, it describes a process that is almost identical to the process many of us use to make our flutes, and our own reamers, today.


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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 3:31 pm 
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While you are at JSTOR, you might enjoy reading this paper:

"The Flutes of Quantz: Their Construction and Performing Practice" by Mary Oleskiewicz

There is interesting discussion there about how, even in the 1700s, Quantz was well aware of the acoustic effects of chambers in the bore.
In the discussion of his newly created tuning slide he notes the following:

"When the slide is drawn out about 6-7 mm with the longest middle joint in place, the resulting internal gap causes a favorable acoustical disturbance to the bore"

Later on there is a lot of discussion about the impact of blowing style, cork placement and its impact on tuning. Interestingly, Quantz points out that it is important
to cover the embouchure and blow more into the flute, as opposed to what he refers to as a "modern" embouchure approach of blowing more across the
embouchure. The article points out that the tuning of his flutes assumes this blowing style and a cork placement that goes with it (up to 26 mm set back from the
center of the embouchure), and that if the blowing style and cork placement are not followed it can "cause unmanageably low F-sharps and a sagging low D".
Sounds familiar, eh?

The article also states "That Quantz intended his flutes to sound their best at the lowest pitch is evidenced by his use of a single reamer for the longest middle
joint. Other joints he constructed with multiple reamers to accommodate the more rapid taper necessary in shorter joints while maintaining a consistent bore
diameter at the extreme ends of each joint."

Anyhow, all of this was well-known way back in the 1700s.


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 Post subject: Re: Rockstro
PostPosted: Tue Feb 25, 2020 4:13 pm 
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Very interesting. The reedy sound when blowing more into the flute can be helped by a strong undercut or "eccentric" cut. But what about the covering of the embouchure? Does it have an effect apart from flattening the note and making it easier to direct the air-stream into the flute? Would the same effect be achieved with a smaller embouchure cut and a more prononced undercut? I noticed in my own dilettantic efforts so far that the undercut has a huge effect on the timbre. But I haven't paid as much attention on the effect it has on tuning.


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 Post subject: Re: Rockstro
PostPosted: Wed Feb 26, 2020 3:53 am 
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I spent the evening browsing around the JSTOR website and came across this paper:

Woodwind Instrument Bore Measurement by Cary Karp

It has lots of discussion that is directly relevant to this thread, specifically about the techniques involved in measuring
bores, problems to be overcome, and methods for estimating and accounting for shrinkage.

Starting on page 19 there is extensive discussion of the use of multiple reamers to produce irregular shaped conical bores,
and the use of other reamers to produce chambering in precisely the manner I described (i.e. by back reaming from the lower
end of sections). This discussion comes from a 1932 translation of a paper written by Dresden based instrument maker,
Karl. F Golde, who died in 1873, and so it is evidence that these techniques were certainly already well known and in use
during the period that R&R made flutes. And since it pre-dates Rockstro, it clearly can not be sourced to him.

Here is a short quote from the start of that section. There are several pages that follow, discussing how the instrument is
tuned and specifically which notes are affected by the chambering.

"Basic for the purpose at hand are Golde's references both to a specific series of reamers used for boring an oboe
and to an unspecified number of other reamers to be used for chambering the bore at various points." ...


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 Post subject: Re: Rockstro
PostPosted: Wed Feb 26, 2020 8:58 am 
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So it's been established to my satisfaction at least that "chambering" was a real thing.

Did it get "lost" as the boehm flute replaced the conical bore flute?

Is it related only to the third octave? Or would it have value for a flute basically intended to play in only two octaves?


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 Post subject: Re: Rockstro
PostPosted: Wed Feb 26, 2020 10:35 am 
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PB+J wrote:
So it's been established to my satisfaction at least that "chambering" was a real thing.

Did it get "lost" as the boehm flute replaced the conical bore flute?

Is it related only to the third octave? Or would it have value for a flute basically intended to play in only two octaves?


I showed some examples of nice sounding keyless flutes by modern makers that included chambering, so I think it is clear that it can have value in our current context.
I also showed some examples of nice sounding keyless flutes by modern makers that did not include chambering, so that shows that it is not necessary. In my opinion
it comes down to subtleties of the voice of the flute, which depend on the shape of the bore. If you want to make a flute that sounds like a specific pre-existing flute,
the first step is to copy its bore profile.

Think about it this way, even the conical bore itself is not really necessary, since you can make a nice sounding flute that has a cylindrical body bore and a taper in the
head. In my opinion, such flutes do play, and sound, very subtly different though, and many players can distinguish them from conical bore flutes. In all cases you can
measure the tuning using some form of electronic tuner and plot a graph of it against a 12 TET A=440 hz standard and get a straight line, but this is really much too crude
of a tool and too simplistic of a criteria for analyzing the impact of different bore profiles on a flute's performance.

I have not seen chambering in cylindrical bore flutes. However, I do have an interesting bore profile graph of the head of a Rudall
Carte & Co, Radcliff system, flute that demonstrates quite clearly that even when reaming the parabolic head of cylindrical bore flutes
the bore profile was not smooth and regular.


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 Post subject: Re: Rockstro
PostPosted: Wed Feb 26, 2020 11:07 am 
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paddler wrote:
I have not seen chambering in cylindrical bore flutes. However, I do have an interesting bore profile graph of the head of a Rudall
Carte & Co, Radcliff system, flute that demonstrates quite clearly that even when reaming the parabolic head of cylindrical bore flutes
the bore profile was not smooth and regular.
The modelling I did on cylindrical bore flutes for this thread, viewtopic.php?f=2&t=107840&p=1212419, suggested:

1) If you want a headjoint bored with a single reamer, without chambering, the model suggests a stepped cylinder to balance tuning across two octaves.

2) If you include chambering, the model suggests a rather dramatic hour-glass shape in the headjoint, with two big chambers, for balancing tuning across two octaves.


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