I still haven’t got around to the tuning values of the Tuaregs, instead I decided to try to make a proper 20mm Boehm flute in D.
Above, the two versions compared.
The result was quite interesting compared to the previous one, because although the bore was slightly wider along most of its length, the bass was not as impressive compared to the first. Here are the bore shapes. For the first, because the wider part was enclosed that part is estimated based on previous measurement, but where it narrowed again (from 19.5mm) was measured.
Cork face at 0
Light blue No1
The dark blue is as measured, the light blue above that is just a “pleasing extrapolation” of the curve . Either way, it is around 0.5mm difference, which is 0.25mm thickness of wall, which is not going to have a vast effect..possibly.
The red is No2, which actually came out very close to original Boehm, but extended to 19.7mm
For both, bore extends evenly to end at same diameter, from end of graph, slight flare just at end of No1 to 20mm
As I only have the below, which are brazing rods soft soldered in 0.5mm steps, it is all approximate. The measurements were marked at the point I could still spin the gauge fully. Where there was play for one size, but next size up not accepted, is estimate (e.g. 19.7) There should not be ovality, but certainly there will be smaller ridges that might open again after, etc. Still, it gives a good enough idea of the shape at work. I think smaller variations would not affect the sound dramatically. The small gauges are for toneholes.
So, the first bore is clearly chambered, and it has a really good bass all the way through. The second bore is more 19mm Boehm extended to 20mm. The bass is ok, but not as full or easy as the No1, and bass D needs quite precise blowing to work fully, or it is soft or warbles slightly between octaves, or just jumps up octave. As is bass notes are like a loud horn when played full (and the sound clip below doesn’t catch that) , whereas on No1 they have more voice and are also slightly louder. I might try sanding in the chamber present in No1 to see if that has a good effect 
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The sound of No.2 is a bit thinner. Apart from being a bit more “average”, i.e. a wooden Boehm, it plays well, has some nice tone to it when played certain ways and so on. It plays cleanly, and No.1 I am becoming more familiar with and that is playing almost clean now also, but top 2nd octave on and off has wind sound, maybe flute embouchure or smaller top toneholes would help. Both like a fast relatively fine jet, fast meaning more pressure/air than say the Tuaregs or conical bore even. This is good for volume and brightness, however personally I find a very nice full range of sound on rennaisance flutes, which doesn’t need much effort from embouchure (once trained), and that is fine volume-wise for playing in quiet setting. The No.1 does have some very good tone to it, not quite original Ruddal but in that direction.
I haven’t tried a standard 19mm Boehm for comparison. 3rd octave only D I found easy, the harmonics for higher are there but not 3rd.
Made of Maple, both are lightweight. Both play ok with beginner embouchure, with the normal sound that goes with that.
I haven’t finished putting strengthening rings on No.2 , but apart that I logged time taken to make it, and also I include a few more details on making a flute this way, for if anyone decides to try.
Making these flutes.
Log of time taken:
Saw 6 x 95mm pieces of 28mm maple curtain rail, and drill 10mm bore for each 30 mins
Drill 3 pieces to 20mm 30 mins
Drill 3 pieces stepped 30 mins
Sand ream taper 30 mins
Glueing total 30 mins
Sanding outside flush 1 hr
Cork 15 mins
Oil 15 mins
Marking and Drilling 30 mins
Shaping and Tuning 1hr →
That is five and a half hours if all goes smoothly, and that is a minimum of actual time working, not including any making of tools, waiting, pondering etc. The tuning is for acceptable level if holes drilled near size etc. , but I will easily spend several more hours over a few days on a new design to bring the tuning close. The reinforcing rings are extra, the flute plays without but they are needed for normal handling, so those are another hour or three depending on method used. Also, finishing is at choice but I like to lightly sand the bore after grain has had opportunity to rise, will add good coats of oil a few more times also.
1 Maple curtain rod, shameless.
2 The 10mm drill fits similar sized tube, glueing that in place did not stop it spinning though, so plates added to hold it. The 10mm bit goes half distance, trying to finish the starter bore outside the jig would end off centre, so I took to turning the blank around and meeting in middle. Far side allows reaming spade bits through.
3 After 10mm bore.
4 Part reamed to 16mm and 20mm. I found 16mm then 20 mm, a cm or two at a time each (important that the 10mm guide reaches the pilot bore), was faster than just 20mm. Bits get hot fast, allow to cool or in glass of water etc.
5 Blow out at end, this seems to limit itself to within radius, the excess is knocked off carefully from outside with a chisel, and sanded even. Set drill with release ratchet to medium or less, so if it catches it releases.
6 Finished piece.
7 The wood sits in this channel, epoxy and sawdust placed around piece of wood when set in exact position ( centre end of wood on drill bit start and end position). Aluminium wrap stops the glue glueing the wood.
8 Wood in place.
I used 95 mm lengths, those seemed about right but other lengths possible. The wood is held tight by the beam pictured, see previous post.
1 10mm tubing to fit on spade bit to keep it centered while drilling wider from 10mm starter bore. Make sure lined up well at center, gaps were filled with sawdust and superglue to make a temporary tool.
2 Scarf on pole, don’t use these parts of the pole.
3 Sanding reamer, on 10mm bar, could be made hand sanded then spun on drill to round properly.
4 Sand paper wraps (see previous posts somewhere). This time I step drilled in 1mm increments first, and the convex reaming then took half an hour. Don’t force the sanding reamer tight, just let it work with medium resistance. It took two wraps of grit 40, and one of 80 .
5 As the convex half was glued first before step drilling and reaming, a longer 10mm guided drill bit was needed, so here it is spade bit fitted to 10mm tube
6 As so. Different width bits are interchangeable.
7 For the convex end, 10mm pipe was used to line up the pieces for glueing, with glue beaded on both sides of join. Remove pipe before it gets glued, but after wood is glued enough . The pipe pictured here was to join the 20mm bored sections in line, was made by wrapping tape to exact diameter. Check bores line up well before trying to glue, that outside of flute is straight.
Picture of halves after glueing, and on right once fully reamed, then glued and sanded.
I guessed the tonehole location start points, and they are close enough for a D flute. Narrower bore they will be moved south, larger embouchure they will be moved south. For this plan I had to do a lot of undercutting, so I think they could be moved north a little to avoid that. Overall they could not be made much smaller, because the toneholes below any of the top three are main venting for 2nd octave. If too small then octave spacing is uneven, and though approaching the convex section if moved north, if I remember Boehm himself is said to have taken the view that the convex was equivalent to a fixed length, which would possibly mean octaves don’t tighten simply by moving same size tonehole north. Equally, change of convex might change octave spacing. These are all details for anyone else to play with.
A simple way to understand octave tuning is if TH1 is blown at 1st then 2nd octave on a flute, then try the same with one, another, and various lower toneholes covered, and note the discrepancy between octaves. This way you will find which toneholes are serving as main 2nd octave vents. 1st octave is less affected by less lower venting. Obviously the toneholes just below have an effect, but even closing TH 4 can stop TH1 even sounding when covered. In fact at first I thought this flute would be unworkable because I could not get TH1 to sound at all, until more venting below was given. It only came into line with the toneholes close in size to as they are presented here. The balance between undercutting, moving position, and tonehole size for enabling good 2nd octave on top notes is beyond attempted explanation or discussion here, and will depend on other flute dimensions anyway. In short, on a narrower bore the toneholes seem to manage to balance 2nd octave while smaller, a larger bore seems to need relatively larger toneholes. The shape of the bore convex will also matter. That is all part of the fun of making flutes, a simple rule is that to raise 2nd octave for a note compared to first, open and then undercut south ( with 1st octave being about in tune), and then find toneholes that affect 2nd most, and open those south also (so as not to lift the tuning of 1st octave too much for those). That could be various toneholes. Slowly the flute tuning should come into balance, and the maker has to decide where to set each limit. For example, all notes will end up higher than intended is ok, or tonehole size limits reached, or discrepancy between octaves acceptable, etc. etc. etc. That leaves even further refinement for the next flute. I don’t say this is the only way to go about reaching good octave tuning, but this balance of tonehole sizing will always be of some effect. Even on No.1 with large TH1, if I close some lower toneholes it does not play second octave.
The tuning of both flutes are not complete, there is some discrepancy due to them being first effort flutes, so reaching TH size limits etc. , but those discrepancies are easily ironed out in a subsequent flute. So this is just an intro rule of thumb design. Also, I tend to leave bass a little low until I am sure to raise it, because the final tuning depends on how I prefer to set/play that particular flute, and the bass notes on cylindrical are a variable to that that least affect others. Both flutes are quite playably in tune though, and as mentioned, the embouchure needed is maybe slightly more difficult than some other for a good sound. If they don’t seem to play too well, keep trying or find someone experienced to trial them. No1 took me about a month of playing every day to figure best set etc. , No2 I was dissapointed with the first day, then the next day I placed it right and it played nicely. Flutes are demanding like that, and you don’t know if it is the design, if it needs cleaning or needs sealing, if it is because own embouchure is not together that day, or if new embouchure needs learning, or what.
Embouchure shape and size is personal choice, I like around 9 or 10 mm for wider bore flutes, but will start at say 8mm and be shaping and testing till I like the sound. After making toneholes, if all else doesn’t adjust to how liked/acceptable, I return to embouchure and adjust and widen that slightly at a time. Here doing that took most of the warble off bass note. It is very hard to tell what adjustment on the flute has done what though, even cleaning, different set, and so on has large effect, so I don’t touch the embouchure again until I have cleaned and trimmed and tried playing the flute over a few days at least.
For the tuning, it is in an unfinished range of 25 cents played straight at the moment, and could be adjusted to about within 15 cents I think. When played different ways the range can be up to 50 cents, but if a style/sound at 50 cents is chosen, then that could be retuned to 15 cents also. In a way, it is a reminder that choice of flute trains embouchure/style a certain amount (because the player adapts embouchure to play in tune). A good point about making an own flute is that the player is able to tune the instrument to their preferred embouchure.
Just shorthand for various details:
Tuning
Range C#+30 to D+20
TH/1st octave:2nd octave Cents off D
1/-5:-20 2/5:0 3/0:5 4/-5:10 5/-15:0 6/-5:5
End/-10:5
Embouchure 11mm along 9.5mm across
Tonehole/distance from Emb/Dia. Round
1/224/9.5 2/255/9.5 3/292/9 4/349/10.5 5/377/11.5 6/423/9 End 510 mm 19.7 dia
Wall thickness at Embouchure 5mm, TH1 4.5mm, End 4mm
Undercutting Tonehole
1 all sides much
2 north much, others medium
3 south much, others little
4 all sides much
5 all sides much
6 all sides medium
Reamer
Length 23cm 14mm at start . 16mm at 15cm then following Boehm profile minus1 mm, so with width with 40 grit sandpaper on it is Boehm profile. End 19mm
Step drilled 19, 18 and 17 mm. The steps are kept a couple of cm short of eventual bore profile. Sanded with 40 grit until 17mm reached, i.e. a 17 mm gauge reaches through to cork face placement. Then light 80 grit for smoothing, then later 320 smoothed whole bore. Main bore 80 grit on dowel to first smooth then 320.
Sound clip
https://e1.pcloud.link/publink/show?code=XZ4Q98ZJW7ShbczQMy9ga60lEoiD7meAUOy
As usual no effects on phone from a couple of minutes recording, just as is and not with any particular effort after only playing this flute a couple of hours.
1st scale open, 2nd more closed, short of Roisin Dubh with embouchure more closed, then open. Where tuning is out… reasons are described above, but tuning values given are without any adjustment, just from best set of flute for tuning (which is around best sound also). For a beautiful flute version of Roisin Dubh, Joe Burke (on a Rudall flute I think)
https://m.youtube.com/watch?v=C0XC2vvOJec
That is my curtain pole mostly used up, and I leave the design and method at that.
. With olive it just was like the outside, a bit slow but very reliable. To make a whole conical bore needed two wraps of 40 grit if I remember, then I think one of 120 (or one, then two).
