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jose_luis
(1356 points)
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I have seen this concept several times in the Forum and I confess I do not know what it exactly means. There seems to be "blow hole undercutting" but also "tone holes undercutting".
I would like to learn about this subject and have an idea why this make a difference in the sound produced by the flute and the difficulties in their manufacturing.
Thanks!
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jose_luis
(1356 points)
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Thanks. I enjoyed doing the factory visit tour.
There is a simple but interesting explanation about the meaning of the different "cuts" in Yamaha flutes. I had not seen those explanations before.
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jose_luis
(1356 points)
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Now, there seems to be also a kind of tone hole undercutting. I suppose it cannot be done with drawn tone holes (this would weaken the hole tube base too much).
So, for tone hole undercutting, what is the advantage and how are they made?
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Micron
(1321 points)
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Air is "whizzing" in and out of tone holes.
Undercutting can reduce turbulence as the air goes around the sharp "bend" at the bottom of the tone hole, so that the air whizzes in and out of the tone hole more easily. This can affect tone and the pitch of the note.
Note that the embouchure hole not only acts as place to initiate the sound. It is also a tone hole for every note we play.
Most clarinet tone holes are undercut, especially on professional instruments. Likewise on hand-made recorders.
Undercutting has a lot more importance when the tone holes are rather long and narrow, compared with the diameter of the bore of the instrument.
Flute and sax tone holes are mainly large compared with the diameter of the bore, so undercutting is not so significant.
However that embouchure hole "tone hole" on flutes is rather deep and long, so undercutting is quite significant.
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Bilbo
(822 points)
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I think that the drawn and/or undercut tone holes are considered more efficient and may aid a bit in projection but aren't all that important.
On the soldered tone holes (especially older instruments) the silder seal must be good or the flute will play weak.
Another point about drawn holes is that generally the tone hole edge may be rolled and the width of that edge may be three times thicker than on soldered ones. This makes the necessity for a level tone hole all the more important.
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jose_luis
(1356 points)
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I suppose that drawn tone holes should have a "not so sharp" (word?) bend at the joint of the hole wall with the body tube. Because of the drawing process, the joint should tend to be round and not sharp.
In any case those holes would be difficult to undercut (if at all possible), but could be re-formed by stamping or a similar mechanical process. Is it so?
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Bilbo
(822 points)
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I would say so. (Not in that end of the business) but the thing is that the drawn ones can be formed to do a similar thing.
I remember a discussion with Galway and Johan Brögger about his design ideas and he was advocationg a certain shape to the hole which produced a venturi (sort of) effect. I think that he was writing/speaking about his double conical tone holes shape. This concept may improve the efficiency of the tone. See the Brögger interviews at the bottom right of the page:
http://www.thegalwaynetwork.com/interviews/intervue2.htm
These interviews are very educational, lengthy and difficult to understand but in the second interview beginning at about 19:20, he discusses in depth these tone holes and the diameters.
My point is that there is a certain school of players that are more into the traditional older French flute model. This would be the soldered ones with little or no undercutting. They can project a fine tone without all of the modern additions that change to tone from the older sound to a more bright & edgy one.
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Micron
(1321 points)
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"I suppose that drawn tone holes should have a "not so sharp" (word?) bend at the joint of the hole wall with the body tube. Because of the drawing process, the joint should tend to be round and not sharp."
True. However in most cases, the dies used to draw the tone holes result in a pretty sharp bend. In theory, a lot of undercutting could be done with drawn tone holes.
On the other hand, considerably thicker metal is used for soldered tone hole walls, so undercutting can also be done with them. Although I don't think it is normally done.
I don't think undercutting tone holes on flutes makes enough difference to bother with. as I wrote, it becomes significant when the diameter of the tone holes is small, and the height large, relative to the bore, i.e. when there is significant resistance to the movement of the air, oscillating in and out. This is not the case with flute.
"... but could be re-formed by stamping or a similar mechanical process. Is it so?"
It would not be practical to re-form the tone hole shape after manufacture. Reforming to undercut would distort the height and shape of the rolled edge."
<Added>
"I don't think undercutting tone holes on flutes makes enough difference to bother with."
That is, apart from the embouchure hole, which acts as a tone hole. It does indeed offer significant resistance to the movement of air, because it is tall and narrow, so undercutting makes a difference, which is why it is done. It effectively makes the EH tone hole larger.
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JButky
(461 points)
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What about the things that you don't know that you don't know about? (:-)
Joe B
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jose_luis
(1356 points)
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To know that one does not know so many things is a sign of wisdom; to ignore that one ignores so many things is a sign of ignorance... 
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Patrick
(1372 points)
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I know the things I think I dont know are the the things I really know I dont know
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searching...
