I took the embouchure fields at face value - the diameters in the two directions and the wall thickness at the embouchure. The values are used differently between whistles and flutes.
One thing I stumbled on with that calculator (Flutomat may be the same) is that you have to start entering the tone holes at the bottom because the values in the fields are updated when a hole below is altered. I suspect the experts are used to everything (except the embouchure if there is no tuning slide) needing to be got right from the bottom up.
Those two goals are fundamentally at odds with each other. If you want the tonal response to be even, then the tone holes need to be equal in size. In this case, the geometry of the bore will determine their location, and hence the ergonomics. If your bore is cylindrical in the body and has a slight taper in the head, then the spacing of the tone holes will be something like those on a Boehm flute, and they won’t be reachable.
As you reduce their size and move them up the bore to be reachable, you immediately start to alter the tonal response, with some notes, like E on a D flute, being weaker and veiled. But that isn’t necessarily a bad thing. The irregular tonal response across different notes in the scale is one of the things that gives our simple system flutes their characteristic sound, compared to, say, a Boehm flute. Depending on the musical genre that can be a good or a bad thing. Music isn’t just mathematics and acoustics. What matters is often emotional, and what happens in the space between the notes, both tonally and temporally, if critically important.
Well, all this to say that there is a big space for making trade-offs, and ultimately you should let your musical goals guide you, not just the mathematics.
I am very much in agreement. My goal is to create something with my own hands that will play reasonably well, trading off between tuning, tonal response, and ergonomics. I’m under no illusions that I have the skill set(s) required for this balance, but it sounds like a worthy challenge. Also, it wouldn’t hurt to have a flute that could withstand the harsh environment at the brewery where I work.
That sounds like a reasonable approach. (Though to be honest, bamboo is CHEAP… I got enough for three flutes for $2.50CDN) PVC is more readily available though… and uniform, so I think I’ll make a couple of trials with that.
Thoughts, opinions, recommendations on offsetting the L3 and R3 finger holes? It’s not something that I particularly care for, but it may make the stretch more manageable on larger flutes. To be honest, I don’t prefer piper’s grip either when I can avoid it, but it’s looking like it might be necessary with this flute.
I’ve made a lot of bamboo flutes at this point (a few hundred anyway–never kept an accurate count). Making a great bamboo flute is extremely tricky, and I think the most important factor in the whole process is bamboo selection. If you can acquire a lot of bamboo pieces then you can cull them, selecting those that are as close to your target dimensions as possible. Pat Olwell once told me that when he was making bamboo flutes, out of every ten there might be three or four that were worthy of selling, and maybe one that was really great. And that’s after he had a ton of practice. My own experience has been the same.
And the quality standard you are setting is another important factor. Lots of bamboo flute makers create instruments that are decent, but usually not great. They might have a sweet sounding first octave, but the second octave might be horribly flat. Tuning might be uneven, etc.. The most consistent bamboo flutes that I’ve played have been xiao and dizi from some of the more reputable Chinese makers. These makers have access to large groves of black bamboo, and they are clearly very experienced at harvesting and culling until they get pieces that are suited to their needs.
But as paddler points out, the organic nature of bamboo creates a real puzzle. Measuring the bores with conventional gauges doesn’t work in most cases because you have too much variation in the bore between nodes. So you might slip a t-gauge in there, but once you lock it you can’t pull it back out because of some narrow spot in the bore. Throw in variations in wall thickness and the variations in bore diameter and making calculations is no longer possible. I’ve never used flutomat or any of these other design tools, but I expect that on bamboo you are wasting your time. You would do better (IMO) to create a PVC prototype with such tools, getting your finger hole size and placement dialed in, and then simply use that as a loose reference when you go to work with the bamboo.
I love the fact that bamboo is such an organic and unpredictable medium to work with, and it is incredibly satisfying, BUT…you have to be okay with lots of trial and error, especially if you are shooting for a pretty high standard of quality. If you have access to bamboo, it can be inexpensive and plentiful, so at least this trial and error won’t be costly in terms of materials.
Thanks Geoffrey. So much excellent information in your post, but I’ll focus on this nugget. The one thing that really stood out on my first try is that the second octave notes are almost a semitone flat. This is an error I’d rather not repeat. I think it’s because I guessed at the embouchure hole placement. I have ways to test this theory before I put another piece of wood at risk.
When I had a photography darkroom, I treated my discard prints as my “classroom”. Anything that was not fit for display was always good for experimenting with toning or spotting etc. By that token, this flute is not a failure; this effort gives me free rein to experiment with the techniques material and tools of the process. There’s a lot of life left in this wood before it becomes kindling.
Boy, this thread has brought back a ton of memories. In the late 90s I made maybe 5 or 6 bamboo flutes, copying one I bought at the local renaissance festival. However, due to the variance in bamboo pieces, I realized consistency would be hard. I had made one good enough to learn on, better than the renfest one, but I always felt I wanted a better flute. Then, I discovered the flutomat on C&F in fall of 2002, and I switched started making PVC flutes. Consistency was there, I sold them via a local music shop (they were solid, in tune, beginner flutes), made enough to buy a 3-piece Dixon and decided I didn’t have time nor the inclination to keep at flute making.
So, I second (or is it third?) the suggestion to switch to PVC for a while before moving back to bamboo. Taking the material variation out of the equation at first will make the process much more fun.
I am leaning in that direction as well. I had an early experience with a poorly made (and garishly decorated) PVC flute that turned me off of them some years ago. Perhaps I will be more invested with one of my own making.
I am still experimenting with the first bamboo effort so I will have a better handle on the materials when the time comes to try again. I drilled out the end node and replaced it with an adjustable cork. It didn’t take much to find a position that brought the first two octaves pretty much in tune. Kinda… some notes still won’t match up.
One thing I have already learned is that what some people call “organic” as regards bamboo as a material translates to “non-linear. The predicted embouchure location in relation to the end plug does not match. I suppose this may have something to do with the variances in the bore. I don’t have the figures in front of me right now; I’m trapped in a brewery.
This brings me to one of the reasons I am trying to make a low-cost/low-maintenance instrument.
Career number three (or four) is brewing beer for a local seasonal restaurant. Brewing days can be long and boring, typically with a couple of hour-long stretches where I have to wait until the next stage begins. I spend a lot of that time playing a whistle. I’d rather use the time to focus on my flute skills, but I don’t like the idea of subjecting my more precious instruments to the harsh environment of the brewery.
So, it’s bamboo, or PVC, or 3D printed… each have their own appeal. Time will tell where I have the most success.
The advantage of bamboo over PVC is that the bore inside a piece of bamboo is typically not a cylinder. With PVC you get a predictable cylinder, but without some kind of correction inside the head bore, the upper second octave notes will be too flat. With the right piece of bamboo you can get something approximating a Boehm style taper in the head that brings the upper second octave notes into tune. But every piece of bamboo is unique in its profile, so what you learn in terms of hole placement on one piece won’t precisely translate into correct placement on the next piece.
Also, I would not say that bamboo flutes are low maintenance or particularly robust. And while the raw materials may be inexpensive, the work that goes into making a really good bamboo flute is considerable. So they aren’t disposable items. A really good bamboo flute is something to be valued highly.
Amen! I consistently spend way more time working on bamboo flutes than I do on their wooden equivalents. And there many of them get discarded, even after a lot of work has gone into them. So bamboo might be light on the pocketbook (if you have a local source), but it is far from being light on labor or time.
I wonder if it might be more viable to use bamboo as an outer shell for the flute and line the interior with resin. If you put the right amount of resin inside, close the ends and then spin it fast with a motor for eight hours while the resin sets, the resulting bore would be smooth and cylindrical, giving you a product that feels natural but is internally perfect and waterproof with the best sound quality. This would also work for a host of lightweight woods, and it could bring more fragile types of bamboo into play too where they need reinforcement anyway.
That may be an option, but I doubt I have anything near the skill set required to pull off such a feat. So far I have consistently underestimated the challenge of creating an instrument of my own making.
Hmmm…I’m not sure about that approach. Cast bore bamboo flutes are out there (Monty Levinson makes his cast-bore shakuhachi flutes), but the usual approach is to use a mandrel inside the bore, letting the epoxy set around the mandrel. I don’t think spinning it will give you a cylindrical bore–I think it will (at best) just create a slightly more constricted version of the bamboo bore you are laminating it on to. And of course the problem of sealing the ends and coming up with an effective way to spin it are another thing.
I’ve made cast-bore flutes on quite a few occasions, but my approach is different and I’ve always used wood for the outer shell (I have so far not found bamboo that is straight enough for this approach, but it is possible to straighten bamboo if one is motivated). But even if you have a nice, straight length of bamboo to work with, you face another issue to do with wall thickness. If you are using something really thin-walled like Assam bamboo, this method would probably work well. But with some of the thicker walled bamboos, by the time you add a cast bore, then you have really thick walls, with deep chimneys at the embouchure and finger holes. This isn’t necessarily a deal-breaker, since the cast bore shakuhachi have quite thick walls, but it will require some compensations.
But for someone dabbling with their first bamboo flutes, doing a cast bore would bring a whole other level of difficulty. It is messy, requires some special fixtures and tools (including a pressure pot, depending upon what type of resin you are using) and would complicate the process by a lot.
I haven’t tested the fast rotating approach yet, but intend to try it out. I’ve used a silicone bore mould previously with a metal tube inserted through it to keep it rigid. I used to seal the bottom end of it with tape, then drop a little resin in from the top to make a strong seal without the weight of a high column of resin driving leaks. Eight hours later it’s fully leakproof, so I can then fill the tube up full height, then open it a day or two later when it’s adequately cured. I now use UV resin for sealing things, and that cures in twenty seconds, eliminating the eight hour wait.
Spinning it fast instead of using a bore mould would get a perfect surface every time, and it would be level from one end of the tube to the other, making it internally the same as a PVC pipe, but like glass, so if you can get the tuning right on a PVC pipe first, that will transfer across well. A metal tube can again run right through the centre and a motor would turn that directly. One end would be sealed first using UV resin, then the right amount of warmed craft resin would be poured in from the open top end before sealing that end quickly with UV resin, then it can be laid horizontal for spinning with a motor. There will be no leak. (To measure the right amount of resin, fill the whole thing with water, then measure the volume of the water and subtract the required air space volume for the bore, excluding the metal tube’s volume. You then need to dry it completely.) To control chimney height, place the metal rod off-centre if necessary by setting its position carefully relative to the ends of the tube at the side where you want to drill the holes. You might need to tape weight onto the side the rod’s closest to if the resin’s going to be thinnest there so that it spins without vibration.
“But for someone dabbling with their first bamboo flutes, doing a cast bore would bring a whole other level of difficulty. It is messy, requires some special fixtures and tools (including a pressure pot, depending upon what type of resin you are using) and would complicate the process by a lot.”
Certainly no pressure pot. I use food-safe clear resin and there’s no mess with the process. No tools beyond metal rods and silicone rubber solution to make bore moulds. But you can start off with PVC pipe and then transfer the design to resin tubes made inside any kind of cylinder or approximation of a cylinder. A bigger challenge would be to do this with a conical bore. Spinning it with a tilted rod probably wouldn’t work for that, but a silicone bore mould could certainly handle it, though making one the right shape with a very smooth surface would be tough unless you can buy a drill-your-own-holes flute with a perfect bore from a good flute maker to use that as the model. A perfect piece of bamboo for a conical flute could also be used though for a mould to make consistent copies of the interior geometry, fitted inside very slightly wider bamboo tubes with less perfect shape, or you could use the same or slightly narrower width of bamboo tubes and sand out some of the interior until the bore mould fits inside.
I’m picking my way through the code behind the ‘original’ Flutomat and Hans Bracker’s development of it. To get almost the same tone hole positions the values to put in two of Hans’ extra fields are: endef=0.3 (Hans multiplies bore diameter not radius) and temp=73 F
The embouchure size - or even if it’s a flute or a whistle head - makes no difference to the tone hole positions as those are calculated as differences from the open end. The complicated end effects at the window/embouchure get subtracted out so are not even included in the calculation. Embouchure position is a separate calculation.
I’m still puzzllng over the embouchure hole position. The Flutomat one seems too long and sometimes doesn’t calculate. The Bracker one is a better match to a couple of measured flutes. This is not much of a problem if one has a tuning slide and starts off making tone holes with the open end note a bit flat. But for a bamboo flute it would be tricky. Best to have an idea of what a slightly flat length is by trial and error I think.
One possibility might be to have a vent hole below the lowest tone hole so that it can be taped over a little if it goes to sharp. There is an 8-hole version of the flutomat that allows for two vent holes, but both have to be used. I think what I will try is using the Bracker 7-hole calculator but using the extra hole as a vent hole not a thumb hole.
For the too-sharp first attempt - if a small piece of the next bit of bamboo down was glued onto the end of the flute the join could be hidden with a thread binding. No-one would ever know.
Silicone bore molds are something I’ve done, but I’ve not used UV resin. I’ve heard of the craft resin but never tried it. Is this something you mix? If so, how do you manage bubbles? Or is the cure slow enough that they have time to work themselves out? If they are a non-issue that would be very attractive. The epoxy resin mixes I’ve used before definitely needed a pressure pot or you end up with air pockets.
As for doing a spin-cast on the inside of a piece of bamboo…
I know that this is done for regularizing the inside surfaces of pipes (for example), and I can see it working very well with a wooden shell because they are already a very regular cylinder. I’m trying to imagine what the behavior of the resin would be if your “tube” were an irregular piece of bamboo. Bamboo is never truly straight, so there would be a lack of concentricity relative to the rod running down the center. In short, bamboo is always a bent tube, and even if you straighten it out it is never perfectly straight. Would you achieve a truly cylindrical cast by doing this? There may be some simple physics that says it will create a perfect cylinder in relation to the spinning axis, but my imagination is having difficulty with that (which is not to say that it won’t happen).
From what I’ve read, this type of spin casting (to create a smooth inner surface) is typically done with something that is already a straight cylinder but whose inner surface is not completely smooth, but I’d be interested to hear how it works if you try it with something like bamboo. Here is an exaggerated drawing showing typical bamboo geometry with a straight rod running down the center.
If you spin it, will the resin settle in the low spot and create a cylinder relative to the center rod? That’s obviously the theory, but I wonder if it works in practice? And of course this presumes that you have a good way to center the rod with the ends of the bamboo. And I’m curious as to how the resin would be distributed before starting the spinning process.
The idea of extra vent holes is definitely on my mind. My two other wooden flutes, from different eras, and with widely different hole sizes, both have a pair of vent holes at the end of the flute. (Well, on my keyed flute, they are accompanied by the C and C# keys.)
My first goal for the time being is creating an instrument that will play in tune in a given key. I’ve picked up a length of PVC and will see what I can do with that. Extra vent holes are another step down the road. I am saving my remaining bamboo for something special once I feel I have a handle on getting a working instrument.
That sounds like a good plan toffle! You can play with the PVC and practice tone hole placement, embouchure cut, undercutting, etc. Being consistent, stable, and more forgiving, I think it’s a good place to practice before trying bamboo again if you want to do that. The skills you learn on PVC will benefit you moving back to bamboo.
So, I now have a PVC flute blank that plays in tune (within 5c) D4, D5, A5, and D6. Far beyond my expectations. It seems to favour D5 over the low D, but they all play freely. It was a lucky cut, as I was trying to incrementally creep up to pitch, and I expected at least one more cut to get up to pitch. The plug position to achieve this feat of tuning is 19mm from the middle of the embouchure hole. I would have expected 17.3, as that is my diameter.
Inner diameter - 17.3mm, wall thickness - 2mm EOF to plug - 558mm. It’s this last figure that has me puzzled.
So now I’m paralyzed. Putting the same numbers into Flutomat and Bracker, I get really different spaces for the tone holes. Hole 6, my next step, is either 54.5mm from the end, or 77.8mm. This disparity persists even if I force the hole diameters from one calculator to the other. I know the conventional wisdom is to drill small, and gradually increase the size of the hole until each successive note is in tune, but 55 to 77mm hole placement? That’s a HUGE discrepancy.
I’m stuck.
I know several of you know enough to figure your hole placement without the use of calculators, so I’m inclined to trust your experience here.
