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PostPosted: Wed Mar 20, 2019 2:58 pm 
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Let's establish a common fact or three, then I'll ask my big question!

FACTS!

Given a simple flute, cylindrically bored (with no taper at the head or anywhere)-- with evenly sized and shaped tone holes and undercutting, with the 2nd register of its lowest lowest hole tuned well to an octave--, the upper registers will be increasingly flat at higher tone holes. This is why many flutes have a tapered bore in the head: the tapered bore in the flutes head compensates for this problem and allows the registers of high and low holes alike to be tuned well.

Given a specific constant embouchure and other conditions, widening a tone hole will sharpen its note but will affect the upper registers differently than the lower.

Undercutting upstream or downstream will sharpen both the fundamental and the upper registers, but undercutting upstream will raise the upper register less than it will raise the fundamental (will shrink the octave), while undercutting downstream will raise the upper register more than it will raise the fundamental (will stretch the octave).

( More info: see "FoMRHI Comm. 2068 by Jan Bouterse", or definitely don't attempt reading the C.J. Nederveen :P )

QUESTION!

Can we make a simple flute, cylindrically bored with no taper, with registers in tune for all tone holes, given some set of varying hole sizes and/or undercuttings?

(Also, what issues might this present for other aspects of the instrument?)

Please discuss and or give a simple answer!

THOUGHTS!

Theoretically we could make such a flute: the tone holes would need to widen as they progess up the flute, and/or tone holes lower on the flute would need to be undercut upstream, mid-flute holes would have no/little/even undercutting, and higher holes would have downstream undercutting. Would it be possible to make all of the tone holes roughly the same "size" and merely use undercutting to tune the registers?

Ready to be shut down but also super hopeful this is possible...

Thanks everybody!

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PostPosted: Wed Mar 20, 2019 4:47 pm 
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In practice the amount of compensation you can achieve by undercutting tone holes or adjusting tone hole size is insufficient to make up for the widening of the octaves unless you also use some kind of taper in the head or the body of the flute. Flute designs such as the bansuri with their very thin walls and very large tone holes seem to get the closest, but the extremely large tone holes make them difficult to use for ITM because you lose the ability to perform crisp ornaments etc.


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PostPosted: Wed Mar 20, 2019 5:20 pm 
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Paddler has summed it up. The North Indian bansuri is the most balanced, open-hole cylindrical flute out there, in terms of tuning. But as he says, not ideal for ITM.

But it has a larger bore for the key, thin wall, large tone holes and a stopper that is pushed very close to the embouchure hole. The larger bore and the greater venting of the large finger holes prevent that "strangulation" of the tone that might occur as a result of pushing the stopper that close.

The result is a flute with superb intonation through both octaves with almost no undercutting necessary (or possible, given the thin walls).

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PostPosted: Wed Mar 20, 2019 6:33 pm 
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I would be hesitant to call anything in FoMRHI as fact.

The only way to observe the effects of hole size, undercutting, undercutting shape, wall thickness, bore shape, etc. is to simply make a bunch of instruments of a type and iteratively see what it does. For my flutes and the holes which are closer to the embouchure than most Irish flutes, sizing the holes affects the pitch of the fundamental the most. Undercutting has little effect on this pitch unless the undercutting starts increasing the actual diameter of the hole. So I always leave a little bit of the hole cylindrical where it exits the body. Since I place my plug some 24mm to the center of the embouchure I tune the 2nd octave with a fairly aggressive undercut on the fingerholes. The shape of the E and A undercuts greatly affect how those notes play with respect to the remainder of the scale. I usually go for a straight sided taper, as opposed to flaring. To a tuner, the 2nd octave plays about 20-30 cents sharp on my flutes - the same when I play a modern flute by a good maker.

This is what works for my instruments but may not apply to ones by another maker.

Casey

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PostPosted: Wed Mar 20, 2019 7:33 pm 
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I think a simple cylindrical insert in the headjoint, such as described in http://forums.chiffandfipple.com/viewtopic.php?f=2&t=107840&start=45#p1212787, will balance the octaves with far less fiddling than undercutting all the toneholes.


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PostPosted: Wed Mar 20, 2019 9:01 pm 
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Tunborough wrote:
I think a simple cylindrical insert in the headjoint, such as described in http://forums.chiffandfipple.com/viewtopic.php?f=2&t=107840&start=45#p1212787, will balance the octaves with far less fiddling than undercutting all the toneholes.


Did anyone come to any conclusions as to whether the insert had any negative effects on the response of the flute? I've only messed with the Fajardo wedges, which I wasn't crazy about, but I'm curious about the bore inserts discussed in the older thread. I remember Terry mentioning that his experiments played differently from a normal flute.

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PostPosted: Thu Mar 21, 2019 1:27 am 
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Thanks all for the quick replies!

paddler wrote:
In practice the amount of compensation you can achieve by undercutting tone holes or adjusting tone hole size is insufficient to make up for the widening of the octaves unless you also use some kind of taper in the head or the body of the flute.


Yeah, this was my main concern. That insufficiency.

But never fear! I am not yet entirely convinced!

Thank you Geoffrey for the very relevant information on the bansuri. I want to look into that more now.

And thank you Casey for sharing some of your design choices. I actually find what you said encouraging for me to see what I can do as I place, widen and undercut the holes on my next flutes.

Tunborough, the insert is a clever prospect but wont work for my situation:

Basically, I'm making 7 holed wooden simple flutes, out of one solid piece of wood. I'm also hoping to minimize the number of large or specialized tools necessary. Thus trying to avoid having to do any reaming, etc, if possible. Id like the flutes to be very simple, simple flutes.

I will say that in posing this main topic question, I am assuming that the locations, as well as the effects of hole sizes on nearby holes (wider holes sharpening upstream holes by decreasing impedance, and flattening downstream holes by effectively increasing bore size, etc) -- im assuming all of this is taken into account in advance. In other words, it is given that those variables would be worked out. For example, im not talking about fixing an existing flute. It might take lots of trial and error to actually work out how this new flute would be measured, but thats besides the point.

So it's not a question about whether enlargening a tone hole will sharpen the fundamental too much compared to that toneholes previous pitch, etc, because that would be accounted for via the holes placement in the first place: What Im asking is about how the different toneholes given their respective sizes and undercuttings would relate to one another, in the end result. Anyway!

A few ideas moving forward:

I think I will try adjusting the upstream space so that the mid range toneholes are in tune moreorless without undercutting. Generally speaking this would make the upper register sharp in the lower tone holes, balanced in the mid tone holes, and flat in the upper? Whereas if the stopper is too far in, then the upper registers of the lower toneholes would be way off and the upper toneholes would be spot on, and if the stopper is too far out, then vice versa?

Also I will use a relatively thick wall to magnify the effects of undercutting?

I will undercut upstream on the lower holes and downstream on the upper holes. And maybe even have the lower tone holes smaller and the upper toneholes larger, although ideally the undercutting alone would be sufficient.

Of course it wont be so simple as I just put it: it will actually be more of a meticulous intuitive process of widening the holes with a file and tuner, and attending to whatever idiosyncrasies are necessary. Then making another flute. And another.

Something tells me I might want to get a better understanding of what the heck is going on with tonehole lattices and velocities? And cutoff frequencies?

Alternatively, maybe I should just turn off my computer and turn on the lathe. I like investigating all the variables and equations-- but im always reducing them to non-numeric rules of thumb, so they dont rule but guide my work when im actually sitting with the file and tuner.

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PostPosted: Thu Mar 21, 2019 1:43 am 
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adamstjohn wrote:
Tunborough, the insert is a clever prospect but wont work for my situation:

Basically, I'm making 7 holed wooden simple flutes, out of one solid piece of wood. I'm also hoping to minimize the number of large or specialized tools necessary. Thus trying to avoid having to do any reaming, etc, if possible. Id like the flutes to be very simple, simple flutes.


How about drilling one diameter (the "insert" bore diameter) right through the piece of wood, then follow up with an enlarging bit (the "rest of the bore" diameter) up to the point where the insert is supposed to stop? That's only one more operation and since it only involves a little enlarging of the bore it should go very quickly.

If you put a mark or a stop on the shaft of the follow-up tool, you will automatically stop at the correct distance up the bore.


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PostPosted: Thu Mar 21, 2019 1:52 am 
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I accidentally wrote "conical" in the name of this thread, when I meant "cylindrical"!

Not sure if there's a way to delete that. Assume it needs to be done by a moderator. Oh well? Anyway.

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PostPosted: Thu Mar 21, 2019 1:57 am 
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Terry McGee wrote:
How about drilling one diameter (the "insert" bore diameter) right through the piece of wood, then follow up with an enlarging bit (the "rest of the bore" diameter) up to the point where the insert is supposed to stop? That's only one more operation and since it only involves a little enlarging of the bore it should go very quickly.


I like this idea and may try it! Thanks.. I should go back over that thread where you all discussed the insert. (viewtopic.php?f=2&t=107840&start=45#p1212787)

I also might just compromise and get into reaming.

However, for the sake of the science of the whole situation, I think I better try this undercutting idea a bit and see how much juice I can squeeze from it! Would be good to know what is possible..

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PostPosted: Thu Mar 21, 2019 7:29 am 
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adamstjohn wrote:
Terry McGee wrote:
How about drilling one diameter (the "insert" bore diameter) right through the piece of wood, then follow up with an enlarging bit (the "rest of the bore" diameter) up to the point where the insert is supposed to stop? That's only one more operation and since it only involves a little enlarging of the bore it should go very quickly.


I like this idea and may try it! Thanks.. I should go back over that thread where you all discussed the insert. (viewtopic.php?f=2&t=107840&start=45#p1212787)

I also might just compromise and get into reaming.

However, for the sake of the science of the whole situation, I think I better try this undercutting idea a bit and see how much juice I can squeeze from it! Would be good to know what is possible..


Making cylindrical bore flutes will teach you a lot, no doubt about it. The ultimate lesson (I believe) will be that you will need to alter the bore if you want the flute to be in tune. With the notable exception of the bansuri (as described previously) I will go out on a limb and say that none of the complex techniques you described (messing with hole placement, undercutting, etc.) is going to yield a satisfactory result beyond simply allowing you to observe the principles in practice. And by "satisfactory result" I'm speaking specifically about achieving a really well-balanced first and second octave. I think you can make a very nice flute using those techniques, it simply won't be in perfect tune.

Again this depends upon the type of flute you are making and what you want to use it for. But you can move holes around and undercut til you are blue in the face and you won't get a well-balanced instrument, but you can get pretty close--close enough that a good player who is willing to do some more intense lipping can play it in reasonable tune--but you will always have a flat second register, especially near the top of the scale.

Placing and sizing tone holes has some effect, just as undercutting does, but that effect is not radical. I think it is totally worthwhile to experiment because it will teach you a lot about the theory, but don't expect to find the magic combination that is going to make a cylindrical bore flute have good tuning balance across both octaves. Even conical bore flutes and flutes with tapered headjoints don't really achieve that, not perfectly. They just get that extra step closer, allowing the player to manage the rest with minimal effort.

Again, the nearest I've personally gotten with a cylindrical bore is the bansuri. But this is a flute with a wall thickness of 1.5mm, and finger holes that are 11mm+ in diameter and spread out so far that for a D flute you have to use the piper's grip to reach the holes. And it's not perfect either :-) But it's close enough that it doesn't take much effort to play it in tune. Similarly with the Chinese xiao, which is a smaller bore with thicker walls where undercutting is necessary. It gets quite close due to the finger hole layout, but it requires lipping up the second octave.

I've made hundreds of simple, cylindrical bore flutes in an attempt to make a serviceable one-piece instrument that would be usable for various styles of music, including trad. In the end, I made reamers to cut a tapered headjoint, and that was the only way I got a satisfactory result. But of course, some of the "simplicity" has to be sacrificed for this approach.

I think if you can make some type of insert work without strangling the tone, that would still be pretty simple and worth experimenting with.

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PostPosted: Thu Mar 21, 2019 12:37 pm 
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Thanks Geoffrey, considering the various styles of simple flutes that you make, your opinion is very relevant to this.

We'll see how much I delve into this when tuning my next batch of flutes. But maybe it is best-- now that I feel like Ive come close to 'mastering' how to make a decent (albeit necessarily somewhat out of tune) cylindrical, taperless flute-- that I try incorporating reamers into the process.

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PostPosted: Thu Apr 04, 2019 10:18 am 
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It's one thing to preserve the traditional sound, or the traditional playability, or the traditional feel, or the suitability for repertoire. I'm not one who cares one whit for some of the other restrictions such as outer profile, choice of material, legitimacy of keywork, alternate fingering, or manufacturing methods used. If you could make a Boehm flute sound and play like the others while serving the repertoire, I would do so (I believe my flute in F above C comes close). Being modern while being completely traditional is madness that I leave to the likes of Captain Gordon.

Every instrument has compromises, especially to its musical scale (and the note E is probably not a good point of departure). You noted that the upper notes can be flat; I'd like to add that the Boehm taper in the head serves to flat (make flat) the lowest notes in the whole compass of the instrument as a way of correcting the tuning. The adjustment is overall, not just aimed at the middle register. This is a slightly different perspective, which may be necessary later on. Likewise, to undercut "upstream" compresses the octave, while undercutting "downstream" stretches the octave. When tuning, you should look at the registration first, then absolutes later: this is another issue for perspective.

Yes, you can undercut below to make corrections in the tuning. I once made a HiD fife (piccolo size) with extremes of this undercutting. Some of the tuning was improved, but the tone and playability suffered. This geometry will not solve all your problems. Makers have been dealing with this issue forever. It has been said that a flute needs either a taper in the head, or tapers in the body, and I tend to agree.

Other issues: Even if you force the notes to be in tune, that doesn't mean that note will produce a good tone, or that the instrument will respond to the player's efforts of enriching the tone. You may find that the instrument can be played into a tuner all day long, and everyone can see evidence of correct pitch, but it may be a lackluster flute. Good tone comes from mutually-enhancing notes of the musical scale (AND their harmonics), resulting from proper design of the physical scale and bore. Also, to get good effect of this undercutting, we're talking about a thick wall, and this adds volume and hence a permutation of the bore, especially as the holes get closer together (farther upstream). A widening of the bore at this point (C# hole) will compress the octave, a characteristic flaw of the "Irish" flutes.

I now make 1-piece drumcorps fifes with a Boehm-style bore in the head. I paid plentibucks for the reamer, but I expect to get a good return, so the expense was justified. Terry's suggestion is essentially my method (drill a pilot hole, then ream to final size and shape, stopping at gauge points). Now the bonafide Boehm taper is a curve, but a straight profile will do fairly well, too. You can probably find a standard tapered reamer for not much money; this can modified for your purpose. Have you tried the Sandner Spike? Fajardo Wedge? I adapt this principle in some of my fifes, and it reflect the bore profiles of some other classic flute bores. You can also effect the Fajardo Wedge by cutting the head on an angle (cutting slightly into the bore), gluing a flat side to the opening, then turning again. I have made fifes with the Sandner Spike, which is still used on the Zauberfloete.

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PostPosted: Sun Apr 14, 2019 11:37 pm 
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So I've started using my tapered reamer. (See thread at viewtopic.php?f=2&t=108339 ) .

After stumbling upon the effect, and then researching more in Nederveen and Benade, I see what Casey and Walt are talking about here.

Casey Burns wrote:
To a tuner, the 2nd octave plays about 20-30 cents sharp on my flutes - the same when I play a modern flute by a good maker.


Benade actually says almost the exact same thing: "25-35 cents more than an octave."

waltsweet wrote:
You noted that the upper notes can be flat; I'd like to add that the Boehm taper in the head serves to flat (make flat) the lowest notes in the whole compass of the instrument as a way of correcting the tuning.


Without a tapered head bore, the second register of the upper toneholes tends to go flat, or at least the octave of those toneholes goes narrow, while the lower toneholes may have relatively perfect octaves.

According to Benade's 'perturbation lines' a tapered head bore will lower the fundamental of the lower toneholes while leaving their second register moreorless unaffected; and as you go up the toneholes this relationship is gradually reversed, whereas at the highest toneholes the fundamental is relatively unaffected and the second register is sharpened.

So this has the effect NOT of bringing the registers of all toneholes into a perfect octave relationship, but RATHER giving all toneholes a slightly wide octave.

The benefit of this is twofold: First off, now the registers are evenly spaced, giving the player a much simpler intonation to lip around should lipping be necessary-- as opposed to a sagging upper register on a flute without a tapered head bore.

Secondly, according to Benade the fundamental tones rapidly rise in frequency as a player blows harder, whereas the second register is relatively unaffected; This means that under harder blowing conditions, the lower register will rise up to meet the second register. Furthermore, I'd add that under softer playing their is still ample room to adjust the pitch with appropriate lipping.

A question here: Now I don't have many proper flutes around, but my standard metal concert flute seems to overblow on point or slightly flat? A narrow octave?

But wait! There's more! Not understanding all this, I was a bit underwhelmed when my new tapered bore flutes were turning out this widened octave. So I thought I'd give them a longer upstream space to compress it back down. Unfortunately, this has a greater flattening effect on the upper notes than the lower (see Terry's page at http://www.mcgee-flutes.com/Stopper.html), moreorless countering the effect of my tapered bore in the first place! Foolish me!

By the way I'm wondering if the D5 in Terry's measurements is an open hole at the top of the flute or rather the overblown end? Does adjusting the stopper not affect the registers of the lowest tonehole?

Thank you Walt for the great post. It was very down-to-earth and informative, lots of good food for thought in there.

waltsweet wrote:
Also, to get good effect of this undercutting, we're talking about a thick wall, and this adds volume and hence a permutation of the bore, especially as the holes get closer together (farther upstream).


This is the next impossible thing I dont think I (or anyone?) will fully tackle. Understanding now that closed toneholes (a widening of the bore) do not simply flatten notes below them, but can have the opposite effect as well. And not just an effect on toneholes immediately below them, but an effect on toneholes quite far down the flute. Again we're talking about Benades perturbation curves, standing waves, pressure waves, etc. Yikes. Complicated.

After all this, I do believe that 1) undercutting and tonehole size probably wont fix everything but 2) they are still essential techniques for the tuning process and may be even underrated in their potential!

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