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This particular design is for a two-piece simple-system transverse flute in G made from 3/4" CPVC plumbing pipe and fittings.
You can get CPVC pipe and fittings at almost any hardware store. The pipe shouldn't cost more than a few dollars and the couplings should be less than 25 cents each.
A rubber stopper might cost around 30 cents while a cork would be a little less. Personally, I like to use corks left over from wine bottles since they're closer to the right diameter. I can get three usable flute-corks out of one wine-bottle cork.
Go ahead and flatten the ends you've just made, both the one on the head barrel and the one on the remaining pipe. Use either sandpaper or the flat file. It's important to flatten them now so later measurements will be more accurate.
Now measure the length of the body barrel (25.0cm) and mark it as you did for the head barrel, accounting for the little bit you'll lose to the saw. Make the cut, then flatten the fresh-cut end of the body barrel. You don't need to flatten the pipe that remains.
Now you'll need a short piece of pipe from what remains, maybe 5 or 6 cm long. If you're working from a long piece of pipe, just cut it off and use it. It doesn't need to be flat or smooth, nor any precise length. Clamp it in an upright position so that it sticks up at least 3cm clear of the clamp and any other nearby obstructions. You'll use it later.
Use whatever knife, ream, or deburring tool you've got to ream the middle-separation out of one coupling. Be careful not to make any deep scratches our gouges inside of it.
Slip the reamed coupling down onto the end of that short piece of pipe you clamped upright earlier. The pipe is being used as a sacrificial holder for cutting the coupling in half. Carefully line up your hacksaw, start slowly, and cut the coupling in half lengthwise. Trust your eyes to guess the half-mark. It's just a lip plate so it doesn't need to be exact. You'll cut into the pipe that's holding it too, but that's okay.
Go ahead and keep that little piece of pipe and the left-over half for later even if you're not planning on making more flutes... yet.
Now use the flat file or sandpaper to round the corners. Then go back and slightly bevel the edges of the corners inside and out.
Measure 11.6cm from one end of the head barrel and mark it with a
line. Your embouchure (blow hole) will line up with this mark.
A paper towel or a rag with a little acetone on it can be used to wipe surfaces which are about to be glued. This gets dirt and oils out of the way and slightly softens the plastic. Follow the precautions mentioned on the acetone container, and be careful not to wipe away the mark you just made! Line up the lip plate right near the mark so that it appears to be centered. That will give you a good idea of how much of the pipe needs to be cleaned. Then wipe that part of the head barrel and the whole inside surface of the lip plate with acetone. You shouldn't need to wait for it to dry.
Apply your adhesive to the inside of the lip plate (not to the barrel), making sure that it's thickest in the middle. Try to avoid bubbles. Then place the lip plate against the head barrel as before, slowly and straight-on to spread the glue evenly. Again, the idea is to avoid trapping bubbles between the lip plate and head barrel. Don't worry much about extra glue coming out at the edges. Just wipe it away for now, you'll get a chance to clean it up nice later.
Wrap your big rubber band around and around (and around) the lip plate and head barrel to hold them tightly together while the adhesive cures.
Wipe the other end of the head barrel and the inside of the other coupling with acetone in preparation for gluing. Spread some adhesive (it doesn't take much) on the outside of the barrel taking care not to slop it over the end. Then shove and twist the barrel into the coupling as far as it will go, seat it completely. Wipe away any excess adhesive if necessary. Check inside the coupling for excess adhesive too.
Put the head assembly aside to cure in a well-ventilated place.
Cut out the two pipe outlines, leaving some extra paper at the zero ("0") end.
Optional:You can put all holes along the same line, or you can offset the third and fifth holes as shown.
Note that there is no need for a "left-handed" flute for the same reason that there is no left-handed clarinet nor left-handed piano. Since you use both hands to play, there isn't any point in swapping sides (unless you unfortunately already learned it that way).
Fold the end of the strip of paper back on itself at the zero-point (so the zero-point is now at the edge). Using adhesive tape, secure the paper template to the body barrel so that the zero-point edge lines up evenly with one end of the pipe. Once you're satisfied that the template won't be easily dislodged, mark the centerpoints of the holes on the pipe by pressing a sharp-pointed tool through that point on the paper template. Remember the tips on working with sharp tools!
Using your pen or marker, write a little "o" on the body barrel to indicate which end is the zero (foot) end, then remove the template.
Take your ruler and lay it alongside the body barrel and make some marks to show the upper and lower bounds of the tone holes according to their diameters. Then use the small knife or deburring tool to open up all six holes to somewhat less than their final size. That leaves room for tuning.
If you've got a generic hardware-store tapered cork or rubber stopper you will begin by setting it gently into the end of the body barrel (or some spare piece of the same size pipe). Use a sharp knife or razor to cut off the part of the stopper which was able to fall into the pipe. The cut must be smooth and flat.
Cut off the larger end (if necessary) so that the stopper you're left with is about 1.0cm long. Then, depending upon how tightly the stopper fits and how much it is tapered, you may need to cut or sand off some of the sides at the larger end so that the stopper will fit completely inside the pipe. Don't cram it in now, just make sure that it's small enough that you can cram it in when you need to but large enough to fit very tightly.
Prepairing a wine-bottle cork is a lot easier. Just cut off a 1cm long piece of it (sharp knife, smooth cut) and sand it down to match the outer diameter of the pipe and it should be about the right size.
Supposing you've been patient though, remove the big rubber band and hold the head assembly upright with the lip plate near the top end and facing you. When looking at it this way, the centerpoint of the embouchure (blow hole) will be 1.3cm from the right-hand edge of the lip plate, at middle-height. Use the point of your knife or deburring tool to mark the hole in the same way you did for the finger holes.
Measure and mark the limits of the embouchure hole based on that centerpoint; 0.4cm to either side and a little more in the up and down directions. Again, open the hole up short of those marks but this time be extra careful to keep the hole as smooth and straight-walled as possible. The embouchure is sometimes better shaped as an oval or even as a very-well-rounded rectangle. Your preference.
Use the knife or deburring tool to take the burr off the edge of the embouchure deep inside the flute, then take the burr off the outside edge. It's best to deburr the inside edge first since you might otherwise nick the finished outside edge while trying to reach the inside. Don't bevel those edges. The edge of the embouchure should not be "sharp" but it definitely shouldn't be rounded either. Sometimes the outer edge can be deburred with a light, scraping motion to get the right edge.
If you're blessed with oily skin, roll the stopper along the side of your nose! Then press that stopper (smooth side going in first) into the end of the head assembly nearest the lip plate until it is completely inside the pipe. Insert the dowel into the other end of the head assembly until it touches the stopper and look into the embouchure to read how far the stopper is from the imaginary center-line of that hole. Use the dowel to push and shove the stopper until it is about 1.8cm from the center of the embouchure.
Insert the top-end of the body barrel (not the "0" end) into the head joint as far as it will go and turn the body so that the holes along its main line are approximately aligned with the embouchure.
At this point, you have a functional flute! Don't get too excited though, it's going to need quite a bit of tuning and a couple other finishing touches before I would consider it to be playable.
Since I haven't written how-to-play instructions of my own, I'll refer you to those on Mark Shepard's "Play a Flute" pages: http://www.markshep.com/flute/Play.html.
You can tune by ear, or use any other musical instrument you wish as long as it can play in the key of G. A fully chromatic electronic tuning aid would be ideal, but they can be pretty expensive.
Cover all finger holes and sound the tonic (the lowest note the flute makes). Then play an octave higher by blowing a little harder. At least it should be an octave...
If the upper note is too low, push the stopper farther into the flute. If the upper note is too high, use the dowel to push the stopper back out some. You should have enough pipe length that the stopper won't hang out past the end of the flute, but if somehow it does just trim it off (and remember to make the head barrel longer next time).
Now check that tonic and its octave against "G" on some other instrument or using a tuning aid. If your flute is too low, you can raise it slightly by filing or sanding off some of the top end of the body barrel (the part which fits into the joint). Not too much, maybe 1mm at a time. Alternately, you can open up the embouchure hole slightly to sharpen the entire flute. After either of these operations you may need to go back and re-adjust the stopper too.
The head end stopper should never be used to "tune" the flute for a playing session. For that, use the head joint. If you need the ability to tune up or down to match other instruments the head joint needs to be built a little differently to provide sufficient mechanical stability and a smooth transition as a tuning slide. But if you only need to make your flute a little flat for a session, pulling the body barrel out a bit should do the trick.
Once you've gotten the head aligned, you should never need to move that stopper nor trim the embouchure again. If you're anticipating playing it in drastically varying temperatures, taking your flute with you into the sauna and then out into the snow, you may want to glue the edges of the stopper if you used cork. Play it for a couple weeks before doing that though... sometimes it takes a while to notice if you're off by just a little. Rubber stoppers will stand up to all sorts of abuse. You can grease them (with silicone) and they won't ever require gluing.
All of the notes should be flat, sometimes terribly flat. You'll start by opening the lowest tone hole (for an A) and simply make the first open hole bigger, little by little, to bring the note up close to pitch. Remember, the only hole you enlarge is the very first one underneath all the closed ones, and you don't bring it completely up to pitch and you certainly don't overshoot. This is only a rough tuning. Get close, but don't get all the way there.
Work your way up the flute until you feel that all the notes of the bottom register are pretty near what they should be. Then check your work by playing through the second register (one octave up) and make any minor adjustments you feel may be necessary. Still, don't tune all the way up to the note. Keep it a little flat.
Once that's done, you'll tune it up right and add any decorations you've got in mind.
Position the flute horizontally so that the holes to be countersunk are facing straight up. (You can do four of the six with the barrel clamped in one position.) Hold your sanding-pipe horizontally, directly across the top of the barrel at a right ("square") angle.
Countersinking, in case you haven't already noticed, is only for the finger holes. Don't countersink the embouchure.
Since you're going to take each hole down to the same depth you'll need to start with the smallest hole (probably the fourth one). File it down, at the preferred angle, to a point where the edge of the hole is still at least 0.1cm thick, no thinner. Notice the size of the countersunk area. The goal is to make all six countersunk areas approximately the same size. Though the holes may take up more or less of that space, the area where the fingers are obviously supposed to rest should be pretty much the same on all six.
Once you've gotten all six holes countersunk to about the same depth, set the medium sandpaper aside and wrap a small piece of fine sandpaper around the piece of pipe instead. Use the same motions to go back over all six holes. This should help smooth out the scratchy texture which the medium sandpaper left.
In the event that you do open a hole up too much, all hope is not lost. If the error is only very slight, you might be able to build up the edges of the hole with a few layers of adhesive (if it has a thick consistency). Otherwise you can use masking tape to cover just the top edge of the offending hole. It's not pretty, but it works.Another option is to make plastic putty by dissolving shavings or filings of pipe material in acetone. Theoretically, this should adhere to the pipe material when applied. I don't know how well it would hold up under actual use... I've never tried it.
Use the knife, file, or fine sandpaper to remove any stray glue and round any sharp edges which might still be around. It's nice to give a very slight bevel to the edges of those tone holes you've just tuned.
A rag or paper towel with acetone on it will clean off all the marker and factory printing very easily. Sanding it off with fine (or very fine) sandpaper is pretty tedious.
Give it a final rinse with warm water to clean any dust or shavings out of the inside.
Any further decoration or polishing is up to you. You can draw on it, carve it, wind it with string or leather... whatever. I've put some ideas in those direections (amongst other hints and tips) on my other simple flute pages.
by Rick Miller
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