By David Osborn

Introduction: Mysteries of the Shakuhachi Bore
The basic external form and morphology of the Shakuhachi is quite simple and visible for all to see:  As a vertical or end-blown flute, it is basically an open pipe with a notch cut in the top end and five finger holes, four in the front and one in the back.  If you want to refine and elaborate on this basic description a bit further, you could say that the Shakuhachi is made from the thick walled root end of the Madake bamboo stalk, with the bottom root end artistically sculpted into a bell shaped flare, showing traces of the original rootlets.  You could also go on to say that, in its classical form, the Shakuhachi comprises six or seven nodes – two to three with rootlets at the bottom end, plus an additional four joints above it, with the top end being contiguous with a node or joint.  You could also go on to describe how the Utaguchi, or mouthpiece, is inlaid with a durable material like bone or water buffalo horn in two different basic designs – crescent shaped or trapezoidal.  All these external “specs” go into making the outer form or kakko of the instrument. 

But, as with so many other traditional Japanese art forms, an elegant simplicity of outer form goes to conceal inner refinements that are quite subtle and complex.  And so it is with the Shakuhachi – its inner core or “heart” – its kokoro – is its bore, which has usually been intricately contoured and sculpted to tune the instrument to exquisite perfection of pitch, tone, dynamics and response.  As with many traditional art forms around the world, the art of Shakuhachi making was subject to a period of artistic growth or evolution, culminating in a state of classical perfection.  The earliest Shakuhachis, the ones played by the priests of the Fuke sect and the basket headed Komuso monks were “diamonds in the rough” – simple open pipes of bamboo with their nodes reamed out, and maybe, at the most, a single coat of Urushi lacquer to seal the pithy interior of the bamboo pipe from the moisture of the player’s breath.  These are commonly referred to as Ji Nashi Shakuhachis, or Shakuhachis “without putty”.  By contrast, the Shakuhachi in its modern or classical form is Ji Ari, or “with putty” – in other words, with their bores sculpted by the addition of layers of Urushi lacquer mixed with powdered clay, or Tonoko.

Bore work is where the real secrets of Shakuhachi making lie hidden, being artfully concealed behind a glossy external coat of lacquer.  My Shakuhachi teacher in Japan, Iida Sesshu, being a Shakuhachi maker by trade, kept a special secret workshop under lock and key, which he let no one else into – this was the secret acoustical laboratory in which he did his bore work.  There are two main schools of Shakuhachi playing, and the instruments of these schools differ not only in the form of the Utaguchi inlay – crescent shaped for the Tozan School and trapezoidal for the older Kinko school – but also in the nature of their bores, and in the process of their bore work.  The bores of the Tozan School Shakuhachi tend to be more tapered than those of the Kinko School; also, Tozan School Shakuhachi makers usually line the bore with a bottom coat of plaster before laying on the finer layers of Urushi lacquer and powdered clay, whereas Kinko School Shakuhachi omit this bottom layer of plaster, using only lacquer and powdered clay to build and sculpt the bore.  And so, Tozan School Shakuhachi tend to have a more polished and brilliant sound, whereas the sound of the Kinko School Shakuhachi is sweeter and softer, more natural and organic in tone. 

The Basics of the Shakuhachi Bore
If you just want to make a “Shakuhachi” that plays in tune in the simplest possible way, you can make one from a section of PVC plumbing pipe that has been cut to the proper length, with the requisite notch cut into the top for the Utaguchi and the five finger holes drilled into it at the proper places.  But the sound or tone quality of this rudimentary PVC “Shakuhachi” will leave a lot to be desired, lacking the full depth and richness of the traditional Shakuhachi sound.  Making such a simple, “minimalist” Shakuhachi will, at the very least, enable a player to learn the basics of Shakuhachi playing and to see whether or not he or she has any natural talent or ability for the instrument.  And the fact that such a minimalist Shakuhachi plays in tune demonstrates a core principle of Shakuhachi bore work: that of harmony and balance.  In other words, all the parts of the long bore of the Shakuhachi are in harmony and balance with each other, albeit in the simplest possible way, with the inner bore diameter of the instrument being the same and consistent throughout. 

In contrast to the simple, minimalist cylindrical bore of the PVC Shakuhachi described above, which has the inner bore diameter being the same throughout the instrument’s entire length, the classical Shakuhachi has a conoidal bore – that is, the bore diameter is wider at the top or blowing end than at the foot or bottom root end.  In this basic “spec” of having a conoidal bore, the Shakuhachi has a lot in common with many other traditional flute forms, such as the Recorder, the Quena, and even the Baroque or Irish Flute.  In addition to this basic conoidal “spec”, the bore of the Shakuhachi is usually flared slightly to moderately at its bottom end, with the diameter at the very bottom of the bore being still narrower than the bore is at the top or player’s end.  The narrowest part of the Shakuhachi bore is usually right around the node that lies below the bottom finger hole of the Shakuhachi.  Below that, the bottom flaring of the bore begins; this flaring can be seen as the natural consequence of boring out the bottom root end of the instrument and filing or rasping the bore smooth at its bottom end.
For a standard 54.5 cemtimeter 1.8 shaku Shakuhachi, a good bore diameter at its top end would be about 21 millimeters, or slightly over ¾ of an inch.  At the bore’s narrowest point, below the bottom hole, a good bore diameter would be around 16 to 17 mm; at the bottom end, 18 to 19 mm.  And a good bore diameter at the middle tenon and socket joint would be 18 mm.  It must be remembered that these bore diameters are approximate and relative rather than inflexible and absolute, because in tuning a Shakuhachi bore, what is important is bringing all its component parts into a holistic, balanced relationship with each other.  The top end of the bore is often flared outwards slightly, to the point where, when cutting the notch for the Utaguchi or mouthpiece, the outward cut does not produce the notch, but rather, the flaring of the bore from the inside; this gives a sweet, rounded tone quality.  The two centimeters or so below this upper flare can often be built up with Ji slightly to add focus and definition to the tone.  Then, below this, the bore contraction is often minimal until the level of the node right above the back thumb hole has been reached; then the bore tapers smoothly and steadily towards its narrowest point before flaring slightly towards the bottom opening. 

These are the generic basics of a Shakuhachi bore – as I said earlier, these are relative and not absolute.  The only absolute in bore work and Shakuhachi tuning is the need to bring all the bore’s constituent parts into a holistic framework of harmony and balance with each other.  In this, each instrument, each piece of bamboo as Nature made it, is an individual, and what one instrument needs to bring it into tune, or into a state of overall harmony and balance within itself, may be quite different from what another instrument, another take, or piece of bamboo, needs.  And so, although I gave you the generic basics of the Shakuhachi bore here, it must be remembered that there can be considerable variation from these generic norms among different individual instruments, and that no two instruments will be exactly alike.  The basic task of the Shakuhachi maker in doing the bore work and tuning of an instrument is to bring out the full latent potential of the original piece of bamboo and turning it into a fine, polished musical instrument.  Each instrument is an individual, just as no two singers are alike. 

Chohritsu and the Fine, Holistic Art of Shakuhachi Tuning
The word chohritsu in Japanese is usually translated into English as “tuning”.  But whereas Westerners tend to get quite analytical and think of tuning merely in terms of pitch, the Japanese concept of chohritsu, especially as it relates to the tuning of the Shakuhachi, is more multifaceted and holistic, incorporating not only pitch or frequency of vibration but also other acoustical parameters such as tone quality, dynamic balance and playing response.  In other words, the tuning of a Shakuhachi from a traditional perspective is bringing the whole gamut of notes produced on a particular instrument into a state of holistic balance and equilibrium with each other – not only in terms of pitch, but of all these other acoustical and musical parameters as well.  Although certain other world flutes, like the Native American style flute, will tune the instrument by altering the size and/or placement of the finger holes, this is not the traditional Japanese way of Shakuhachi tuning, which is to bring all the finger holes and their individual notes into balance and attunement by balancing out the profile and camber of the bore, which pervades the whole instrument and mediates between all the finger holes and their notes.

Before we get to the specifics of the Shakuhachi tuning process, there are certain generalities that we must be aware of, which apply, to a greater or lesser extent, to all flutes.  The first is overall or average bore diameter in relation to the air column length.  If the above generic bore specifications for the standard length 54.5 cm. Shakuhachi are adhered to, this length will produce the fundamental note of a “D” above middle “C”.  However, if the average bore diameter is significantly wider, then the same length of 54.5 cm. would produce a note a little flat of that, even down to a half step below the “D”; conversely, a significantly narrower average bore diameter will produce a fundamental note higher than the standard “D”.  This is especially true of a conoidal bore, which tends to enclose or hold the air in to a greater degree than a cylindrical bore.  In general, a Shakuhachi with a narrower overall bore diameter will have a tone with more focus and definition; Iida sensei would call this shibari, or “squeezing”.  If the bore diameter is too narrow, the tone will be too thin and reedy, and the fundamental note difficult to obtain or produce.  Conversely, an overall bore diameter on the wide side will produce a tone with more body and breadth, but with less focus and definition; too wide, and the upper notes will be difficult to produce or obtain. 

The bore work / tuning process for a Shakuhachi is basically that of going from a rough bore to a smooth, refined bore.  A key objective in this polishing or refining process is to smooth away the “kinks” or bore irregularities produced by the nodes or joints.  Even after the interior of a node or joint has been sanded or rasped away as much as possible, there may still be some kinks or depressions that remain; these are filled in with Ji or tuning material, generally a mixture of Urushi lacquer and powdered clay.  Whether one prefers a Shakuhachi with Ji or without Ji can often be simply a matter of aesthetic preference, with a Shakuhachi without Ji producing a rougher, more rustic tone, even though its notes may be in tune pitch-wise, and a Shakuhachi with Ji producing an eminently smooth, pure tone throughout its range.  The end goal of the fine tuning process for a Shakuhachi with Ji is to have an instrument that plays uniformly throughout its range, with no kuse – no idiosyncratic quirks or rough spots. 

Tuning and bore work on a Shakuhachi is pretty much a balancing act – the higher must be balanced with the lower, and all parts of the Shakuhachi bore brought into the proper alignment with each other.  Since Shakuhachi tuning is a holistic art of healing bore imbalances, parallels can be drawn with other traditional holistic healing arts of the Far East – like acupuncture or acupressure.  In other words, there are certain tsubo or therapeutic pressure points along a Shakuhachi’s bore, each with their own particular remedial indications in the tuning process.  In modern acoustics, we know that a guitar string, or the air column of a flute, vibrates as a whole, which is the fundamental pitch; it also vibrates in parts, which produce the upper overtones or partials.  The pressure point for the second partial or overtone, which is the air column vibrating in two halves to produce the octave, is right in the middle of the bore.  If the upper and lower fundamental notes are out of tune, for example, you would look to correct the bore in its midsection, or to bring the upper and lower halves into balance.  Likewise, the special tsubo or pressure point for each note and its octave lies midway between the hole associated with that note and the Utaguchi.  The heart of the tone for each note lives within these pressure points.

Mapping Out the Shakuhachi Bore: Areas of Special Concern
There are various points or areas along a Shakuhachi bore that are, for one reason or another, areas of special focus or concern.  From top to bottom, I will map them out here: 

The Top End or Mouthpiece:  The top end or Utaguchi / mouthpiece area, where the instrument meets the player’s lips, is an area of special concern, since it channels the player’s breath into the instrument.  As I said earlier, I prefer this upper portion to be flared outward ever so slightly, and the notch in the Utaguchi to be created not by the initial 30 degree outward cut of the exacto saw, but rather by an outward flaring of the bore that rings around the entire top end of the instrument.  Doing so creates a soft, sweet quality to the tone.  Another option, which is not always necessary or desirable depending upon the particulars of the piece of bamboo being worked on, is to build up the bore ever so slightly by the application of Ji or tuning material around the bore right below the top flare; this, if it is not excessive, can bring focus and definition to the overall tone of the instrument. 

Upper Internode or Third of the Bore: The tapering of the bore in the instrument’s upper third, or the area above the node that lies above the back thumb hole, and below the uppermost mouthpiece area, is often very slight, even to the point at which the bore can be almost cylindrical in this portion.  This creates an upper resonance chamber, if you will, that can add a dimension of depth or spaciousness to the overall tone.  This, of course, is not an absolute, but it often works well – the analogy here is to the head joint of a baroque flute, which is cylindrical, in contrast to the markedly tapered conoidal shape of the bore below the head joint.  Below this upper resonance chamber, the Shakuhachi bore usually tapers quite steadily and markedly towards the point of maximum narrowness or contraction around the node that lies below the bottom finger hole.
The Middle or Socket Joint Area: In making a Shakuhachi in two parts, a tenon and socket joint is created in the middle of the instrument, midway between the third and fourth finger holes from the bottom.  The traditional method for doing this is to inlay or insert a piece of narrower diameter bamboo into the bottom half to create the tenon, and to sculpt or hollow out the socket in the upper half, below the fourth finger hole.  The insertion of the narrower diameter portion of bamboo to create the tenon often creates gaps or irregularities in the inner bore that must be filled in and smoothed over with tuning material.  Nevertheless, the inner bore diameter of the inserted piece of bamboo cannot be too narrow; the bore diameter here should be roughly midway between what it is at the bore’s widest point and at its narrowest point – according to the generic norms cited above for the standard size Shakuhachi, 18.0 to 18.5 mm. is a good width.  Besides making the instrument more compact and portable when not being played, the middle socket joint makes for easier access to the bore during the tuning process.

Around the Nodes: The nodes that occur naturally in a stalk or pole of bamboo have presented special problems to bamboo flute makers around the globe.  Symbolically and philosophically speaking, the nodes represent points of difficulty that need to be worked through, just as the periodic problems we encounter in life.  Each node along a Shakuhachi’s bore presents the Shakuhachi tuner with a special set of problems and challenges, and nodes that are straighter are inherently less problematic than those that are a little crooked, or which create “kinks” in the bore that need to be smoothed out.  To straighten out crooked nodes, Shakuhachi makers will heat the node area up over a hibachi or little Japanese charcoal stove until it is flexible, and then rope it into a mechanical press to straighten the node out.  The general procedure in dealing with nodes in the bore is to first sand or rasp them out as much as possible; then, if any kinks, ruts or irregularities remain, these are usually filled in with tuning material – but this might not always be necessary, depending upon the particular tuning needs of the individual instrument.   

Around the Finger Holes: The finger holes, and the various notes they produce when they are opened, can provide valuable clues as to what is needed in the fine tuning or sculpting of the bore.  This is especially true with the finger holes in the bottom half of the instrument, where the bore is narrower and more tapered.  If a certain note produced by the opening of a finger hole sounds weak, bloated or unfocused, chances are that the bore area surrounding that finger hole is wider than it should be.  Conversely, if the note produced sounds excessively tight, pinched or constricted, the bore surrounding the finger hole may be too narrow in relation to the whole.  These local considerations must be balanced with a consideration for the whole. 

The Bottom Joints or Nodes: The bottom joints that lie below the bottom finger hole of the Shakuhachi are probably the most distinctive part of the instrument, where no two instruments are alike.  How the internal nodes are configured, and how sharply or shallowly the bottom of the instrument is curved, if at all, must be dealt with and tuned or refined on an individual basis.  One thing I have noticed in observing different instruments is that Shakuhachis that are more sharply curved at their bottom end tend to have their bores less conoidal or wider at what is usually the narrowest point, at the joint or node that lies right below the bottom finger hole.  In addition, any ruts or gouges in the bore that are created by drilling out the bottom nodes must be filled in to a greater or lesser degree depending on the particulars of the piece and its tuning needs.  The narrowest point of the bore is a natural focal point for the sound or tone, and how it opens out into the open air in the bell that lies below it is also critical.

The Bottom Bell or Flare: The bottom flare in the Shakuhachi bore can be seen as the natural consequence of drilling out the bottom or root end of the bamboo, which is quite solid and dense at that point.  Beyond this, the bottom flare serves not only to project the sound outwards towards the audience after it has been focused at the bore’s narrowest point; it also can serve to fine tune the instrument, particularly its fundamental note, which is produced when all the holes are closed.  The more the bottom flare is opened up and the wider it gets, especially at its bottom-most end, the higher the fundamental pitch will be.  And so, there can be considerable individual variation between different instruments as to the degree of flaring of the bottom ends of their bores.    

The Materials and Methods of Shakuhachi Bore Work
As I said earlier, the main materials that are used for Shakuhachi bore work are Urushi lacquer, which can be colored either black or red, which is mixed with Tonoko, or powdered clay, which serves to thicken the mixture.  The more Tonoko, or powdered clay that is added to the mixture, the thicker it becomes.  If there are bigger ruts or potholes to fill in the bore, then a thicker mixture is desired, and more Tonoko is used; if the buildup of Ji is to be thinner and more subtle, then a thinner mixture with more Urushi lacquer is used.  Each successive layer of Ji or tuning material is allowed to dry thoroughly before the next layer is applied, and the tuning process can last weeks, even months.  Urushi lacquer is made from the sap or resin of a certain poisonous plant that is related to poison oak and poison ivy, and many people can be sensitive to it, especially if the lacquer is not completely dried or cured.  Those who are sensitive to poison oak or poison ivy are usually hypersensitive to Urushi lacquer, which can provoke outbreaks of skin rashes.  The best first aid remedy for rashes caused by Urushi lacquer is the topical application of the juice from a fresh Aloe Vera leaf; Calamine Lotion also works well.   

The Urushi lacquer and the powdered Tonoko clay are mixed in the right proportion for the job at hand and applied by means of a long, thin instrument of bamboo that resembles a palette knife to the interior of the bore.  This is a process that requires considerable manual skill and dexterity – the Japanese call it ude, which literally means “arm”, signifying technical skill and know how in one’s craft.  You may know theoretically exactly where the bore needs to be built up, and exactly where the Ji mixture needs to be applied, but actually applying it and getting it there in precisely the right amount and distribution can be quite a different matter.  I believe that it would be possible to use synthetic lacquers with less toxicity and irritation potential than Urushi lacquer, with the main condition being that it cannot dry too quickly – the mixture needs to have a consistent viscosity and stickiness, or relative lack thereof, throughout the entire application process.  In addition to easier portability, the main other reason that Shakuhachis are now made in two pieces is to facilitate the application of Ji or tuning material to the bore.

How complex and involved the tuning process is depends, to a large measure, on exactly how authentic the Shakuhachi you’re making is; the more traditional and authentic the Shakuhachi, the more complex and involved the tuning process, and conversely, the less authentic the piece of bamboo you’re working on, the less complex and involved the tuning process.  If you are making a less than authentic Shakuhachi with, say, only three joint sections or four nodes total, with nodes at either end, and the instrument is to be straight or nearly so, then merely reaming and rasping out the interiors of the nodes carefully with sandpaper glued to a dowel stick and painting the inside with one or two layers of acrylic lacquer can suffice.  The bore will be somewhat less tapered or conoidal than a real authentic root end Shakuhachi, and the walls will be thinner too, giving it less of that rich, deep traditional Shakuhachi sound, but still, it will probably be more satisfying in its overall tone quality than the PVC “Shakuhachi”.  You can either tape all the holes and openings shut except for the top or Utaguchi end and pour the lacquer in and out quickly, or you can use a long stemmed paint brush to apply the lacquer. 

If you are in the process of fine tuning a Shakuhachi bore, how can you pre-test the bore to find out exactly where to build it up for the best results?  A commonly used method is to take a small piece of newspaper and fold it in half once or twice to produce a patch of newspaper about one centimeter square, and then moisten it with water; apply this with your palette knife-like instrument to the interior of the bore in the place that you think would work and play the Shakuhachi both before and after the addition of the wet newspaper.  Does the application of the wet newspaper to that spot bring about a beneficial change in the instrument’s overall tuning, tone and playing response?  If so, then that is where you apply the Ji or tuning material.  Although it may not be as aesthetically pleasing as the traditional clay and lacquer, I have even applied small balls of epoxy putty to the desired spot on the instrument’s interior and flattened them out with the palette knife – and it has still produced the desired result.  So sensitive is Shakuhachi bore work that altering the contours of the bore by even a fraction of a millimeter in the right places, as with our wet newspaper, can have a dramatic effect on the sound.    

The traditional tuning process, which involves the long and laborious application of Ji or tuning material / putty in successive layers as needed to tune the instrument or piece of bamboo at hand can last weeks, even months – which usually makes a Shakuhachi produced in this traditional manner quite expensive.  In recent years, however, the traditional bore work and tuning process has been mechanized and streamlined by the American Shakuhachi maker Monty Levenson with his Precision Cast Bore@ technology.  Instead of successive layers of hand mixed Urushi and Tonoko, Monty uses a mixture of epoxy resins as a kind of semi-liquid tuning “goop”, which he then shapes quickly by the insertion of a semi-flexible rod of hardened rubber with the right contour into the bore, with immediate withdrawal.  Visit Monty Levenson’s website,, for more details on this groundbreaking and time and money saving technological breakthrough.  Similarly, a wooden Shakuhachi that has been turned on a lathe and reamed out mechanically can have a bore that is precision engineered to the maker’s exact specifications, with nothing more than a superficial application of Urushi, or some other form of lacquer, necessary to seal off the bore from excessive moisture.

Internet Resources for Shakuhachi Tuning and Bore Work
I must confess here that in my many years with the Shakuhachi, and the many homemade Shakuhachi that I have constructed, many of them in a less than authentic and traditional style – and consequently much simpler bore work – I have never entered into a formal apprentice relationship with a master Shakuhachi maker, although my studies with Iida Sesshu sensei in Japan did give me many insights into Shakuhachi making and bore work.  But I have always remained an outsider looking in when it comes to the inner secrets of the Shakuhachi maker’s craft.  What I have presented to you here is merely the sum total of all the various observations made and gleaned from the various Shakuhachis I have known.  In addition to making my own instruments from scratch, I have worked on or overhauled other Shakuhachis, which were either rough Ji Nashi instruments or old Shakuhachis I picked up in antique stores in Japan.  In your own studies and investigations into this area, your personal experiences may be different, and lead you to conclusions that are significantly different than my own.

My intention here, in addition to offering you the fruit of my own studies and observations, is to refer you to a trio of three American Shakuhachi makers who have attained a remarkable degree of mastery in the craft of Shakuhachi making, and specifically in the fine, esoteric art of Shakuhachi tuning and bore work.  These three individuals are Monty Levenson (, John Kaizan Neptune ( and Perry Yung, with his Yung Flutes channel on YouTube.  Monty Levenson has perfected his Precision Cast Bore@ technology, which greatly simplifies and streamlines bore work.  John Kaizan Neptune has done innovative and groundbreaking research into Shakuhachi acoustics, and offers the fruits of his investigations on his website.  And the YouTube videos of Perry Yung on his Yung Flutes channel are probably the best introductory videos on Shakuhachi tuning and bore work that are available to the general public.