Making the Supercorder Straight Flute

by Craig Carmichael July, August 2025. Please feel free to copy and distribute in full or in part.

This book isn't complete yet. I'm available for questions, comments, feedback.

CraigXC
at
post.
com

Chapter 1: Intro  - complete
Chapter 2: The Bore, Drills and Reamers  - complete
Chapter 3: Turning and Shaping the Outsides  - complete
Chapter 4: Tone Holes - Finger and Key Holes, Special Drilling - in progress
Chapter 5: Making The Keys - not ritten yet
Chapter 6: Making Porcellain Beak & Block - not ritten yet
Chapter 7: Tuning, Voicing - not ritten yet

This book is long overdue.

Note: Most of the images can be viewed larger using "Open Image" in web browser.


Chapter One: Intro

   I created this new musical woodwind instrument with beautiful sound from September 2003 and on through the end of 2006. It started with a couple of unique design ideas. I couldn't get any recorder makers to try them and finally decided if they were ever to see the light of day I would have to make my own instrument-s. I improved on those ideas with some new ones found or occurring to me along the way. I made about twenty, of varying features. A few I sold. I have one that I still play. I've played it in music jams, and in amateur orchestras and concert bands in place of oboe or flute. (Mostly oboe - the pitch range is good and often oboe players are hard to find.) People like the sound. Fortuitously I have a very few unfinished ones in various stages to use for illustrations herein, and I have held onto the various jigs and special tools, which are specially made for the job but mostly pretty simple. I won't describe the instrument or extol its virtues here. I've done that on the general info web page and in the short videos.
   In order for it to "take off" and become popular, somebody needs to start making them. I could write just enough detail and provide measurements so that experienced recorder or other woodwind instrument makers could make them. But they probably wouldn't. So instead I'm writing this complete book so that anyone with mechanical aptitude will understand the essentials of making woodwind instruments in general and more specificly exactly how to make this new flute. There are three main areas of craftsmanship involved. I learned them as I went and I pass on my techniques herein. I'm certainly no "authority" on any of these subjects. I learned enough for what I was doing:

* Fine woodworking for the main structures of the instrument, the head and the one-piece body.
* Fine metalworking rather akin to jewelry making for the keys.
* Pottery for the porcelain mouthpiece - the unique beak and block with "as you play" fine tuning. (Of course if desired, the mouthpiece might be done with other materials.)

   With the lovely sound and easy playing being very attractive to musicians and listeners, once it is made available it's popularity will surely grow and I can see someone making a whole new and probably lucrative business, even a career, out of making and supplying them. I am an inventor and was moving on into other exciting inventions even before I finished creating the final instrument - it was never about business for me.

Who wants to be first?


The Name: "Straight Flute"? "Supercorder"?

   "Supercorder" is the name I originally picked in 2003. It reflects the origin and aspirations of the instrument. But "recorder" was always a silly name, only used in English. In other languages it's "block flute", "sweet flute" or "beak flute". (And I expect [could be wrong] that the name "flute" originally came from the carving of a flute into the beak of the recorder to form the windway. This would mean that the name "flute" is theoreticly a misnomer for transverse flute since it has no windway or flute.)
   Furthermore, many traditional "dyed in the wool" traditionalist recorder players don't even like the "supercorder", whatever the name. It's other more "mainstream" musicians who accept it as a "real instrument" and like the beautiful "recorder" tones with the strong, rich sound of the lower notes. (where most recorders are quite weak and transverse flutes sound 'thin' in the low range)
   With the reflection of time, I think "selling" it as the "Straight Flute" is probably best: descriptive and unassuming, a "natural" for everyone - especially non recorder players. It sets it apart from "transverse flute" while retaining the appropriate "flute" description. (Most people usually just call it "your flute" when talking to me, even if I had told them it was a "supercorder".)

   Officially I'll title it "Supercorder Straight Flute" -- from which appellation doubtless everyone will quickly drop the word "Supercorder" to make it two syllables instead of six. To be unambiguous I'm going to continue to call it "Supercorder" herein since that name is unambiguous - it applies to nothing else.

   Some of this info (or "these infos" for those who prefer a plural form) is (are) very specific to the supercorder. Other parts may be described as pertaining to "recorders in general", "woodwinds in general", "music in general" or maybe even "Everybody knows that! Why are you bothering us with surplus info that just makes for extra reading?"

   Anyway, I hope that most musicly and mechanicly inclined readers, including those who have never thought to attempt making a woodwind instrument before, will be enabled to make a fabulous F alto flute by the info provided herein. ...not that the first one or the first few would be at all a trivial project. But potentially it could turn into a rewarding business or career.

Transposition

   Recorder has always been played with untransposed music. I learned to play F alto recorder this way. It is more flexible because it makes it natural to read parts meant for other untransposed instruments like flute, oboe, violin, piano or voice. (If I play a "C" recorder (soprano or "bass") instead of F alto, I have to think a bit about the fingerings as I play.) I don't care whether people adopt transposed sheet music or not, but in describing an instrument pitched in F, we run into the confusion of nomenclature, especially for people who have always played transposed woodwinds. "All holes closed" low F on the alto recorder is described as "low C" on most wind instruments whatever the actual pitch. I am using actual pitches herein. One must therefore be aware that when I speak of Eb (for example), that note has the position and fingering that corresponds to Bb in transposed terms on most woodwinds.

Protect Your Hearing

A little caution: In the few years of making and endlessly tuning supercorders, I did my hearing some notable damage. With that (and everything else over the decades) I have entered "impaired" territory. Especially the higher notes, literally, can gradually be deafening. Hearing loss is cumulative and so far no one has ever found a way to make lost hearing come back.
   A good practice when practicing and playing, is to put some cotton batten in your ears. Keep a few little cotton swabs in your instrument case, and rip off a couple of pieces for your ears before you start to play. This protects them considerably without markedly muffling the sound and stifling the pleasure of playing. I wish I had known this when I was young. Wax earplugs or other stronger hearing protection is better for sessions of tuning an instrument, which may be long the first few times until a good feel for what is needed is gained. I strongly recommend AT LEAST cotton.
   Beethoven was only the most noted of many musicians who have gone deaf. (Probably from playing a too-loud piano a lot over the years.)
  (BTW I expect that to use a hearing aid is a "slippery slope" because once one is turning up the volume of sounds to make them out, one is probably doing incrementally more damage, and so making sounds ever louder and more damaging.)

   Lost hearing also makes one more susceptible to 'everlasting' tinnitus, which is caused by susceptibility plus electrosmog - EMF voltage fields emanating from any oscillating electricity from 50 Hz power lines and house wiring way up to cell phones and WiFi. It takes days to fade and no one is ever away from electricity that long, so it's 'everlasting'. Electrosmog is everywhere where people are. Along with hearing loss, perpetual ringing in the ears reduces the pleasure of music.

The Dimensions: Vibrating Air Columns and Pitches

   Obviously the length - and air volume - of a wind instrument is going to determine its overall pitch range. The effective length and volume of the air column determines the wavelength of the sound. One will never find a bassoon the size of a piccolo.
   Woodwind instruments play notes in a scale by opening finger or key holes that effectively shorten their length. To oversimplify, a hole half way up the tube will half its length and double the pitch - an octave higher. In general, the effective length can be increased and the pitch lowered by having a narrower tube, resisting the vibration of the air column more than a wide tube. The effective length can also be divided in half, thirds or more. One is then playing a "harmonic" of the basic pitch of that length of air column. In woodwind instruments this may be induced by having a small air hole around half way along the bore, such as the recorder's part-open thumb hole, which doubles the pitch of several otherwise identical fingerings. Double the pitch is an octave, eg, C3 instead of C2. 1.5 times pitch would be a fifth higher, eg, G2 instead of C2. So the third harmonic, splitting the air column into thirds for 3 times the pitch, would play G3 instead of C2. Fourth harmonic is C4, fifth is E4, sixth is G4, etc. (Horn/brass players know the whole series to the 12th harmonic and beyond - the lips set the harmonic... Am I straying far from the essential topic here?)

   The length of the supercorder is the head (142mm) + the body (377mm) + the protruding part of the beak - (minus) the length of the socket and tenon (25mm), where the two pieces overlap. Total without porcelain beak: 494mm. This length is optimized for playing down to E above middle C, up almost 3 octaves to five ledger lines C or higher. In a recorder, the actual vibrating air column is the length from the window (the hole of the whistle) down the tube to whatever holes are open to provide the different notes.
    I used wood at least 44 mm square. (preferably starting out a little larger.) That leaves enough diameter for the deep labium surround in the head, and to be off a bit when drilling the long body bore.

   The supercorder body is one piece instead of the traditional two because the overlapping shafts of the keys allow no convenient break point. Anyway it's simpler - except for having to drill quite a long straight hole for the bore. In recorder or woodwind parlance the head and body are often denominated the "head joint" and the "body joint". Supercorder has no separate "foot joint".


Chapter Two: The Bore, Drills and Reamers


The the two main pieces, the Head and the Body, are each made from a block of wood. It is desirable to start with a block that is larger than the finished diameter. How much larger is desirable depends mainly on the accuracy of the drilling out of the bore. The long bore hole in the body is hardest to keep well centered in the wood by the time the drill bit comes out the far end. The suggested starting dimension is about 2 inches by 2 inches square for both pieces. So:

Head: 50mm * 50mm * 142mm (slightly longer if the ends are to be squared off on the lathe later)
Body: 50mm * 50mm * 379mm (ditto)

With careful centering, 44 mm square is the thinnest -- unless the labium surround in the head is turned smaller than I was doing them. (I think a couple of mine were a bit smaller, eg, 42 mm. The sound may be slightly different. It might even be worth making a smaller diameter head to hear how it affects the sound.)


   After the length of the instrument, the bore through the head and body is the most critical component. The reverse conical bore profile is part of what gives the recorder its sound character. Every minute change to the shape and volume of the bore markedly affects the tuning of the instrument. The lower octave is affected more by the length, while the upper octave (second harmonics) is affected more by the volume. So in part the two octaves are brought into tune by getting the bore and its profile right. (Not to digress... more under "Tuning".)

   The "long bore" of medieval alto recorders is the best acoustic length, while the "short bore" of baroque instruments allowed players to easily reach the low F/F# holes with their right little finger. Here keys and the longer bore are definitely a better solution. The sopranino or flautino, the tiny "piccolo" recorder an octave above the alto, seems to be always "long bore", and has more notes into the third octave than the "squashed" baroque alto, which only reaches high "G" but even lacks the F#.

   The Joachim Paetzold/Mollenhauer "Modern Alto" apparently followed the long bore of a sample medieval instrument brought to him by player Nik Tarasov, who recognized its acoustic virtues. (Whether Paetzold duplicated this bore exactly or approximately or used his own design concepts I don't know.) For Supercorder I followed the bore of the "Modern Alto". In spite of that, Supercorder turned out differently because of not undercutting the windway, which subtracted volume at the top end of the bore. This was originally accidental, but it works better!
   Later I added a semitone of length to the body to enable a solid low "E" above middle "C", and (being out of fingers) a hole to the side of the bell to hit "Eb" or (with a short tube in the hole) even "D". It may seem a bit hokey to play a lowest note by pressing the bell against one's leg... until one really needs that note and it's there!

Drilling the Body Bore

   After cutting the two pieces to length, the body and head bores are first drilled out and then reamed while the wood is still square. The bore hole is then used to center the wood on the lathe to turn the outside in line with the inside.
   Getting sufficiently straight hole through a long block of wood can be a challenge. I drilled the body bores with a handheld drill and three very long twist drill bits: 1/2 inch, 7/16 and 3/8. I had tape on the drill bits to mark how deep to drill, to a certain depth with 1/2 inch, deeper with 7/16 and through to the end with 3/8. The inverse conical bore is at least 3/8 inch wide to the end, but a 1/2 inch hole would be wider than the reamer toward the small end. Just drilling 3/8 inch all the way would work but there'd be quite a lot of extra reaming to do. I made a drilling jig to try to get the three concentric holes straight and in line and come out the far end fairly near the center of the wood.

The body bore drills: 1/2, 7/16 and 3/8 inch by 18 inches long. Why are there four? The first 3/8 inch
bit - the one that goes all the way through - wasn't quite straight and I had to buy a second one.
(A straight one will roll smoothly on a flat surface.)




Two views of the angle iron bore drilling jig.
I had different pairs of guide blocks for slightly different cross sections of wood.
After drilling so farthe drill hits the first block and one has to un-clamp
the piece and the clamp closest to it and move them closer to the front end.
By then hopefully you're off to a good straight start.

   That's just how I did it. Others might have better tools or methods.


Reaming the Body

   I made the body bore reamer from a piece of 1/8 x 3/4 inch mild steel bar about 450mm long. From the slight "shoulder" (see image) the shank part ends and the reaming part starts. The reaming part is long enough to go right through the body bore and do the bottom end cleanly. Two corners along the edge of the reamer are sharpened (at 90 degrees to the face) to scrape out the bore to the desired profile when one turns it clockwise. The other two edges are slightly rounded off to follow the inside curve of the bore, providing enough support that the reamer scrapes smoothly without "jitter", but not binding.


   I was usually putting the flat shank of the reamer in a vise and turning the piece of wood. Even shaving a small amount of wood at a time, a considerable force is needed to turn the reamer - easier to turn the larger square piece of wood. Later I cut down the the shank end a bit and soldered a piece of 3/8 inch pipe onto the nub, per the image. I put the reamer into a slowly turning chuck and, holding the wood (gloves!), I bored out three or four body pieces in short order. (That's prototype method (vise) versus faster production (chuck).)

   Many or most manufacturers have custom fluted reamers. I don't see the need myself.

Reamers, top to bottom:
* Head Reamer
* Body Reamer
* Two Fine Tuning Reamers


Reamer in body piece, shown almost in to the shoulder, which is the full reaming depth.

   Here are two sets of figures to describe the body reamer profile. The first is measured at right angles to the flat surface - the dimensions one would file or grind it to straight across before rounding off the rear edge. The second dimension is the distance between the points - the actual diameter of the bore, of the wood removed from inside. These are given as measured in millimeters with a micrometer on my actual reamer and slight discrepancies are to be expected.
Measured at: Distance from Shoulder mm
 Width Across
mm
 Width Diagonal
mm
'0' (@2 mm)
 16.80
 17.16
50
 16.03
 16.31
100
 15.00
 15.33
150
 13.80
 13.98
200
 13.12
 13.34
250
 11.93
 12.30
300
 10.90
 11.22
350
 10.30
 10.69
380
 10.20
 10.35

   There was a second, short reamer I used if necessary to raise the pitch of the middle notes in the second octave. Part of it is labelled "Top of Body". Farther up it says "Bottom of Head". If inserted to the line, it expanded the top of the body figures above from the "zero mm" line thus:

  0 mm 17.57 17.90
50 mm 16.40 16.79

   (Well, it's been 20 years. I can't remember how much use I made of the second, 'bottom of head/top of body' reamer, or if I reamed to the marked line or only inserted it a little bit. I do remember ten(?) years ago the instrument I play was getting out of tune. I re-reamed it with just the original body reamer and took out a few small shavings, and it was back in tune. (...to my surprise given how little material I removed.)

Drilling the Head

   I vaguely remember doing this in a drill press with a fat drill bit. After the through hole I drilled in 25mm with a drill of about 24 mm diameter to make the socket for the joint. I held the piece with a big (15 inch) crescent wrench on the square piece of wood. I also used a cheap drill press that was small enough to stall or the chuck to slip if anything jammed. It didn't have the power to yank the crescent wrench out of my hand. This was a good safety measure. Otherwise one would probably want a solid adjustable drill press vise to hold the piece. Or use a hand drill with the head piece held in a vise or with some sort of jig.  (Actually I think I started doing it that way later - same jig as the body, above. The drill press was a nuisance for it.)

Reaming the Head

   The short, fat reamer is the head reamer. Instead of 1/8 inch thickness it is 3/16 inch. The length from the lower shoulder is 126 mm. Since the bore is larger in the head, a thicker reamer will turn better, without jitter (hopefully). It is made similarly to the body reamer with two corners sharpened at 90 degrees and the rear corners rounded off to follow the bore profile.

   There are really two 'shoulders' on this reamer: the lower one is at the start of the window and the reamer must be inserted no farther. The 15 mm section above this is slightly wider (~19.4 mm across, ~20 diagonal diameter on mine) and straight. It is where the beak and block go, and that thin reverse shoulder made inside the instrument prevents the block from sliding forward, which would place it below the beak and blocking the window. This position should correspond to where the upper shoulder or mark, 15 mm above, just reaches the wood of the unfinished head. The shank is whatever is above the upper mark or shoulder.

Reamed head.
Note the slight shoulder 15 mm in.

   Apparently I cut a short "nub" on this reamer to insert it into a slowly turning chuck and have the machine do the work. (I don't remember doing it, but there are marks from the lathe's drill chuck on the nub.) I may, again, have held the pieces being reamed with the big crescent wrench to prevent them from turning. or not.

   My 126 mm reamer is actually more than long enough at the bottom because the 25 x 25 mm socket is cut (drilled) into the bottom area.


Measured at: Distance from Lower Shoulder
mm
 Width Across
mm
 Width Diagonal
mm
'0' (@2 mm)
 18.00
 18.52
50
 17.47
 18.16
100
 17.35
 17.83
120
 17.15
 17.75

   We'll cover cutting for the beak and block, and shaping the labium, in the chapter on the beak and block.

On my own instrument the head, top of the wood to the bottom of the delrin ring,
is just 140 mm instead of 142. I already added the ring because the wood
was cut too short and it played notably sharp unless pulled out.
I mention this to say the figures aren't entirely written in stone - Once you've gained some
experience, if something seems to be "off" or if you think it could be better by changing
something, realize you the maker are always free to try adjusting or modifying it.

Socket and Tenon

   These are 25 mm long and about 24 mm in diameter, and of course the tenon at the top of the body fits inside the socket at the bottom of the head to put the two pieces of the instrument together. They must fit just loosely, and a strip of sheet cork is glued with contact cement to a recess turned in the tenon around 12 mm wide (see images). In order that there be no gap, generally the ends of the cork are tapered by sanding so that one end fits over the other. Cork sheets are available in different thicknesses at woodwind shops. It is sanded down until it is a good fit, generally being just slightly higher than the wood of the tenon. And of course it slides in and out much more easily once it is greased with (you guessed it) cork grease from the same shop.

(Tip: If it's really hard to separate the pieces, repeatedly "bend" them back and forth very slightly in different directions while pulling rather than trying to turn them against each other if they won't. This may happen after a long playing as the wood absorbs moisture.)

Two tenons, the top one without cork.
The socket should be square - 24 mm I.D. along its length and 25 mm long like the tenon.
(I started the top instrument just before deciding to add length to get low E and so didn't finish it.
The second one is the next instrument I was making when I got "sidetracked" by other things.
Note also that my idea for a built-in "thumb rest" was changed to a gentle "thumb guide".)


Chapter 3: Turning and Shaping the Outsides

   After making the bores, those end holes are used to center the piece of wood on a lathe so that the outside and bore exactly line up. (I'm not going to talk about how to use a wood lathe and turning tools. I'm sure there's lots of info on line.)

   I wasn't very careful about duplicating exact outer dimensions as I turned new instruments. This (in retrospect: of course!) led to the finger holes needing to be different sizes since they went through different thicknesses of wood, making different "chimney heights" per woodwind terminology. Luckily this can be adjusted by expanding the tone holes. (see chapter on "tuning") If the body is too thin, it my be hard to put in the posts that hold the keys. I aimed for 24 mm O.D. on the straight lower section. (Since this is the narrow end of the inverse conical bore this smaller diameter still leaves good wall thickness.)

The head as I made them is quite large in diameter at the top end, around 44 mm, so the windway is cut in very deep. I heard "shading" the windway made the low notes better and decided to make it that way. I think it's what gives it the somewhat "clarinetish", richer low notes.

   One will note in the image above (at end of previous chapter) that I left a built-in "thumb rest" or "thumb guide" where the right thumb supports the instrument while playing. I thought it was a cool idea. It has a secondary purpose of making a thicker area to mount the B-Bb pipe-key. Later I changed it to a more gentle "thumb guide" as shown. (If you don't like it at all... you're the one on the lathe!)

   The flare on the outside of the bell, except as it might very slightly affect tuning of low E, is pretty much decorative. (I suppose it's also more blunt if one got poked by the end of the instrument.) I didn't notice a difference by flaring it on the inside. (Theoreticly maybe low E is a bit louder?)
   The low Eb tone hole will be affected by bell changes.


Chapter 4: Tone Holes - Finger and Key Holes

   Of course the finger holes go on top and the thumb hole on the bottom. In general woodwind practice, the top and bottom are the edge grain of the wood, with the flat grain at the sides.

   The supercorder generally follows recorder fingerings for notes in its natural key, F, but there are exceptions. (See the fingerings chart.) Sharps and flats are made stronger and generally easier by means of several keys, which allow an optimally placed hole for every semitone. I managed to make this instrument "fully keyed" with just seven keys, which includes a low E key for an "extra" (and often useful) note below low F. Additionally, every key closes a hole and lowers the pitch, where on some wind instruments pressing certain keys opens a hole and raises the pitch. Lowering is more intuitive.
   In addition, lateral finger movement is never necessary. One is either pressing or not pressing a finger down, with some variance for B/Bb (right index finger) and the little finger double keys.

   I am going to boldly claim that supercorder is easier to play in any key than any other woodwind instrument. I've played often in E and even B as well as Eb and Ab. Etc. A Bb clarinet has chromatic notes, but a player may balk if asked to play in keys with more than one or two sharps (which is three or four sharps on that clarinet) - Instead they make separate "A" clarinets for playing in sharp keys.

   In hole placement, tuning of the lower octave is most affected by the position of the hole, it's distance from the window. Tuning of the second octave however is somewhat more affected by the size of the hole than its position. Therefore, to get both octaves in tune, each hole must be in the right place and the right size. And the right place and size are very dependent on the bore. Since supercorder's bore is unique, so are the hole placements. I did much experimenting to determine the best places for the supercorder holes, as a look at the experimental hole jig below will show. I moved the holes around, and changed their size, by soldering and unsoldering washers or pennies with holes in them, replacing them if the hole was too large. From the first marginally satisfactory instruments they were honed to something approaching perfection.

The experimental hole placement jig


Underside view.

Discussion of the tone holes and keys

   Starting from the top, one notices (in some other foto) that the thumb hole is higher up than on most recorders. It seemed to be the best placement. It allows second octave Bb and B to be played with the thumb open and it surely improves second octave D.
   Second Eb is sometime a bit temperamental on my own instrument, but even E can often be played just as / XOO OOOO. (reliably as a D-E trill fingering.) It was quite reliable on some of my instruments. If a maker can make them work well on all their instruments it would be a blessing. (Hold the presses... it depends on adjusting the beak & block! I seem to have forgotten that and should adjust mine a bit better so it plays E -- / XOO OOOO and Eb -- / XOO OXOO reliably!) The shims under my block have compacted a bit over the years.

   At some point I conceived that as E and D were in up the left hand, Eb and Db could most easily be played by using the middle fingers of the right hand, which are not otherwise in use in this pitch range and which only closed a hole, with no keys. Closing either of these two right hand holes alone had almost no effect on the notes in this range. Thus for these notes I conceived the pair of keys linked to right finger rings, allowing an optimum tone hole for every semitone E-Eb-D-Db, as was already achieved for the rest of the scale. It worked marvelously! And again, pressing a finger down lowers the pitch as is intuitive, never raises it. (The idea expanded on a clarinet Bb fingering - what luck that someone gave me a clarinet, as I'd never have bought one!)
   So, E is played as expected, T XOO OOOO, and Eb is T XOO OXOO. Similarly for D and Db: T XXO OOOO and T XXO OOXO. In runs with Eb the right middle finger can simply be held down, eg, held down for the whole sequence: C D Eb F G. (similarly Db)
   I originally conceived that Eb and Db could also be played by moving the finger (L2, L3) up a bit and pressing the 'flat' key with the left hand without covering the hole to lower the pitch by a whole tone. This works fine but I haven't found it to be practical or useful for playing  music.

    The B-B flat telescoping pipe is unique. It was one of my original inspirations for starting the project. Needing to play both these notes is a headache on wind instruments, usually involving a "forked" fingering for one or the other or both. My solution to play either note with only the right index finger was to lightly cover a hole to get B, and to push a bit harder to depress the Bb key as well, for Bb and all lower notes. It works quite well.
   It does have two disadvantages: first, it increases the distance between the first and second right hand fingers. It's fine at the F-alto size, but it probably wouldn't scale well to a longer, lower pitched instrument. The second is that it's harder to make a smoothly working, air leak free telescoping tube than the other keys. (Below is a potential idea to improve the mechanism.)

   The second and third right fingers cover their own tone hole as is typical (note below).
   In addition, they press down the ring linking to the Eb and the Db key. When playing notes in the right hand fingering areas, those rings are pressed down already by the left fingers. In the left hand fingering areas, the otherwise idle right hand is employed to make playing the above "out of key" notes simple.
   It is traditional to offset the hole for the third left finger a bit to make it easier to reach, but not the third right finger. I offset mine a bit for a special reason: I'm missing the last joint of that finger [skillsaw accident when young] and I have to be able to play the instruments I make. Every little bit less I have to reach helps. But many players hold wind instruments, especially keyless recorders, pointed a bit to the right. This offset for the third finger plus the further offset F/F# keys on the fourth finger might improve the ergonomics back to "straight"? I myself can't have a proper feel for this. (If I was missing just a bit more, woodwind playing would be "out" for me and I'd never have developed this instrument!) You as the maker may choose to offset this hole or not, which is typicly made in-line.

   On recorders the third finger usually covers a double tone hole for G & G#. But this arrangement makes low G# and A weak, and G# harder to play (especially along with transitions between G# and any lower notes), so we opt for a separate accousticly optimum G tone hole, which is played by the fourth finger of the right hand via a key. This seems perhaps unintuitive, but consider that transverse flute in effect does the same with the same finger, except that the key is held down to Open the G hole instead of to Close it. It is held down for all notes above G (D in transposed terms). On supercorder it only has to be held down for the very few lowest few notes in the lowest octave: G, F#, F and E.

   The low F# and F tone holes and keys are essentially copied from the "Modern Alto" recorder. (It is perhaps amusing on that instrument to go from a nice, strong low F, F# and G to weaker notes above that.)

   With no more fingers being available I put one last small tone hole down by the bell. If all holes and keys are closed with the fingers and the bell is covered by the leg, A low Eb (E-flat) below low E results. Or, by inserting the "low D pipe" in that hole, it is lowered even more to low D. Unfortunately D and Eb aren't both available except by inserting or removing the short tube. They are weaker notes. (But then most alto recorders only play down to F and notes under about C are weak.)
   One could potentially make a wider bell, or have two tubes, for Eb or D, to effect a longer distance ("chimney height") through the hole and hence to be in tune the hole would be larger diameter and stronger sound. I never tried this. (In fact I just thought of it now!)
   Or perhaps some clever person can figure out keys or holes to get both notes, or to get the "extra" note easily with keys - some sort of "bell key" or even two keys.

   Every extra low note helps when one is playing music not specificly written for the instrument. Celtic music often goes down to D, and for example in Bach's A minor violin concerto it's surprising how rarely one must go up an octave or play a "wrong" note if low Eb is available in the first movement and low D in the second. One recorder concerto by Vivaldi (RV445) goes down to E in multiple places and can't be played as written on most recorders. This is why I pushed the limits of possibilities with the low E key and low Eb or D by "trickery".

=====

   The table below gives the distance and size of each tone hole from the top of the body without counting the tenon. These are as measured or marked on my hole drilling jig, and were derived from considerable experimentation. Apologies for the mix of units. Being in North America, all my drill bits were in 64ths of an inch.
   In sizing the hole drills, it was intended that the holes never be drilled too large, which would make notes too sharp. Rather, they may be a bit undersize (note flat) so that removing surrounding wood will raise the pitch until it's in tune. Then they can be reamed out bit by bit from inside with a 'dremmel motor tool' burr bit. The burr bits I used were small, shaped round and inverse cone. These fit though the hole and so are able to ream it from the inside face so that the outside face of the hole is unchanged.
   Holes that are too large (note is sharp) can be reduced using cyanoacrylate glue mixed with sawdust from the recorder's own wood. But this is more difficult and may be less cosmetic. (Other glues I tried tended to eventually dissolve or come loose with the moisture of playing.)


Finger (Notes when hole is the top open hole, closed) [Rotation from in-line with other fingers - degrees]
 Distance in mm
 Hole size in inches
Left Hand

Thumb (G, F#) [180] 18.5
 1/4
1 (F#, E)
 44.5
 1/4
(E, Eb)
 68
 3/16
2 (Eb, D)
 82
 3/16
(D, C#)
 97.5
 3/16
3 (C#, C) [left ~ 4 mm but usually drilled straight down]
 114
 3/16
Right Hand (mostly!)

"4" - index finger (C, B)
(B, Bb pipe)
 131.5
 11/32
(B, Bb)
(B, Bb pipe)		 152
 3/16
"5" (Bb, A)
 173.5
 3/16
"6" (A, G#) [may be in-line or ~4 mm right (see text), but drilled straight down]
 196.5
 13/64
"8" (G#, G) [0° - in line]
(LEFT little finger, double key)
 220.5
 7/32
"7" (G, F#) [75°(?) right]
(RIGHT little finger, bottom lever double key)
 255
 11/32
(F#, F) [75°(?) right]
(RIGHT little finger, top lever double key)
 280
 5/16
"8" (F, E) [0]
(LEFT little finger, double key)
 310.5
 11/32
BELL STOPPED (E, Eb, or E, D with "D" tube)
 347
 1/4


   In addition to the toneholes, there are six threaded holes to hold the "pedestals" for the rods on which the three sets of double keys pivot. These are all the same size depending on the diameter and threads of the pedestals. I got some pedestals off scrapped clarinets, others I made myself. Generally makers are careful the their pedestal anchors, and their holes, stop short of penetrating into the bore. So ideally to thread the holes one needs a "blind" threading tap, ie, one that will thread to the bottom of a hole that ends without going right through the wood. (I suppose it wouldn't hurt much if the holes protrude into the interior - the tiny space they would add could hardly affect the tuning. But if the bottom of a metal pedestal anchor sticks into the bore, it will either stop or damage the bore reamer. ...and after drilling through into the bore, one will want to run the reamer through it again. Also after some years of playing, an instrument often wants the bore reamer run through it again to shave off roughening wood inside, that can affect sound quality and tuning.)
Pillar Key Set
 Distance Down (top hole, mm)
 Distance Down (bottom hole, mm)
 Angle from in-line with finger holes (degrees)
Eb - Db
 63
 158.5
 90° to right
G - E
 135.5
 318
 90° to left
F# - F
 231
 287
 25° (?) to right

   These angles need not be set in stone. But they work. I chose them as practical and "operable" while keeping them out of the way of other keys and the fingers. I tried to make the F and F# keys the same as the "Modern Alto".
   The diameter of the holes depends on the post's anchor diameter and threads. On my own instrument it looks like I used pillars of a scrapped clarinet. They're about 4 mm in diameter. I don't remember about the threads (and at the moment I decline to disassemble the keys including the pillars).
   For those pillars I made myself, I probably used #6 AWG solid nickel-brass or brass wire cut into short pieces, and threaded them with #10-24 threads, which would mean a drill bit of about 9/64 inches and a #10-24 "bottoming" or "blind hole" tap to drill the holes and cut the threads into the wood. (More in the "Making The Keys" chapter.)

   Tone holes with keys have a special surround. The key pad has to seal against a flat surface, in contrast to the fingers which can cover over the slight curve of the round body. The surround is a slight depression drilled in with a special drill. (Look at a clarinet or an oboe.) I made my pad surround drills by shaping flat "spade" drill bits to the shape I wanted with a file, and soldering a little piece of round brass pipe to the center. The pipe keeps the bit centered on the hole without drilling out any more on the sides of the tone hole.

Tone holes with a ring around them have a different special surround - a little "ditch" just outside of the immediately surrounding wood. The requirement here is that the finger be able to close the hole normally, which means being able to press the ring down until the top of the metal is flush with the surface of the body. Again a special drill bit is shaped as desired.

Specially Shaped Drill Bits  (L to R)
* The bit with the large center nub is to shape the surround of the low E keyed hole. (It's about 16 mm.)
* The similar bit marked (14) mm with the smaller brass tube center is for the Bb and low G, F# anf F keyed holes.
* The third bit marked (8) mm is for the left hand keyed holes Eb and Db. The center is dulled so it won't cut into the tone holes.
* The "notched" bit is for the surrounds of the holes with rings around them: left hand E, D and right hand A, G#.
* Gratuitously included in the drawing: tapered spade bits can make it easier to drill large holes in wood. The tapered edges are sharpened like the flat ends.

   In writing the description of the drills for the image my memory is failing me. It may be that I had another surround that slipped over the above 14 mm bit's brass pipe surround, as it seems too small for the holes. One might well simplify by making the low F/E tone hole the same size as G/F# and F#/F, and undercutting to tune it sharper if F is flat. (or move the hole a touch closer to the labium?)


Chapter 5: Making The Keys

What? There's more?!?

   Metalworking for the keys is more like jewelry work than typical metal work. There are specific components to the keys, which in supercorder include three sets of double keys. (The B-Bb tube is discussed separately, farther down.)
   The metals commonly used for keywork are brass (eg, Cu:Zn 83:17%), and/or "nickel-silver" AKA "German-silver" or as I prefer, "nickel-brass". (eg, Cu:Zn:Ni, eg 65:17:18%) It is 'silver' colored but has no silver in it. These are also the metals commonly used to make 'yellow' and 'silver' brass instruments.)
   They are both ductile and malleable, so they can be formed and worked to different shapes.
  

1. "pillars" or "posts" (brass or nickel-brass... B or NB).
2. axle (piano wire)
3. axle tubes (B or NB)
4. levers (B or NB) The one piece finger rest plus linkage to hold the pad cap.
5. pad caps (B or NB) These hold the pads that cover the holes.
6. rests (B or NB)
7. springs (piano wire)
8. Pads (I used two thin oboe pads and five clarinet pads)

Pillars (AKA Posts)

   The pillars consist of a threaded bottom section that is screwed into the body of the instrument to hold it in place, and an upper cross hole to hold the axle. For each pair, one hole is the diameter of the axle and the other end is threaded to hold the axle in place. As I measure my instrument the cross holes in the pillars are all centered 5.5 mm out from the body except the lower one for the ring keys, which is 7.5 mm. (The body is thinner at that end of the axle than at the top end.)
   Since the axle rod has to be inserted from one end, the easy end is the top for the ring keys and the G/E keys, and the lower end for the F/F# keys. The threaded post should be at the other end.

Axle Rods

   The axle rods are of hard piano wire, [diameter]. They each go between two posts. They are the pivot around which the keys rotate when pressed. One end must be threaded to match its post. The other end needs a slot cut into it with a very fine saw so the axle can be turned in and tightened with a tiny screwdriver. The threads and slot are hard cutting in the hard steel.

The length between posts for the axle is:

Ring keys - 99 mm
F/F# keys - 60 mm
G/E keys - 188 mm

   Axles are generally the exact length between the outsides of the posts but nothing is lost if one end sticks out a bit. Leaving an extra mm or two will allow on case the threads are a bit long, where the threaded end will stick out past the post before it's a tight fit. (One could grind off the excess later if desired.)




The B & Bb Telescoping Tube Key

   One of the features of supecorder that makes it easier to play is this mechanism to play both B and Bb with the right index finger alone. How I made it follows, then a proposed improvement to the mechanics.

As I've made it, this seems to be a mechanicly weak arrangement, prone to leaking and hence causing the lowest notes to squeak harmonics. I haven't thought of a way to do it without a telescoping tube, but one could separate the mechanics of the Bb key lever and cap from the tube so it can't tilt or shift sideways with finger pressure causing tube tilt or rotation, where the pad may fail to close the hole completely. I think the best way to do this would be to have a ring around the C/B tube, hinged above it and closing the B/Bb tone hole below it when the tube is pressed down. There isn't much room for the hinge, but it could ne done. But it might be easiest to solder a pivot tube or other hingesupport to the top-outside of the stationary piece of the C/B tube, on the labium ("upper") side.


Chapter 6: Making the Porcelain Beak & Block

Last edit: 2025/07/30
2025/08/10