The following are several method of construction which can be employed in making a wooden Didjeridu.
This method most closely resembles the traditional ant and termite construction of the Didj. Utilizing a suitable drill bit and a drill or boring machine with enough power to drill or bore it is possible to penetrate a hole through the entire length of the selected wooden or other solid core material. The bits which I have worked with are Forstner, Spade Bit and (a new entry) WoodEater by Magna of Elizabethtown, KY 42701. All of these bits are 1 1/4 to 1 1/2 in bits. The WoodEater in a 3/8 drill with 3 extensions (12 in. long x 3 = 36 in.) will bore a 5 foot length of wood stock in less that 30 Min.
Select and cut to length a suitable stock. Survey the straightness of the stock noting any curves, knots, limbs or other irregularities. If there exists any pronounced curves, carefully plan whether you can manage the boring. Reject this method in favor of the French Bread (see later method) if the stock is so curved that you are not able to bore the necessary hole. If the stock is suitable, secure into a stationary position by what ever mean are necessary. I have used a "Saw Buck" (two "X" shaped frames which hold the wood in the their forks), a standard woodworker's vice, and large "C" clamps or "Bar" clamps attaching the wood stock to a rail on my deck. Attach two string layout lines; one above the stock and one along the side. These lines must extend well beyond both ends of the piece to be drilled in order to provide reference lines to assist in keeping the drill or boring motor at the correct angles. The angles will change in order to deal with any bends or curves. If you have selected a fairly straight trunk or branch your line from start to finish will be almost straight. Drill from one end and then the other. With enough extensions it is possible to drill from only one end but controlling more than two extension (24 in,) is a real challenge. It is helpful to turn the stock in order to compensate for the natural tendency of the bit to drift downward because of gravity.
Stop frequently to assess the angle and direction of your drill in order to avoid boring through the sides.
Do not become attached to any piece of wood until you have completed the hole because a number of things can go wrong.
When and if you complete the bore, the interior shaping of the bell and the exterior shaping can be done with rasp, or other similar tools. Again care must be exercised to prevent cutting into the interior chamber. Sanding, decorating and finishing are the next steps.
This technique is used in the Amazon by some of the native people to make blow-guns. Visualize a baguette (loaf) of French bread with the ends cut off, sliced in half length wise, the center scooped out and the two halves glued back together. Because you are not confined to straight wood, you can use limbs or trunks with some very interesting bends. If you are willing to accept the sound of a constructed Didj and have access to the right equipment this is by far the simplest method of building a wooden Didj. You will need the means to bore a short center hole, a saw to cut the stock in half, length wise and a means of removing wood from the center of the two halves.
Using a drill bit (1 1/4 to 1 1/2 in), bore/drill a hole in both ends of the stock. These holes can be as short at 3 in or as long a 12 in and can be of different lengths. The primary purpose of these holes is to establish reference points for the hollowing operation. With the holes bored, rough shape the outside of the Didj using the holes in either end as a guide. If the bell end is to be larger that the mouth you will need to draw a the correct size of the interior hole on the bell end. Once you have shaped the exterior of both the bell and mouth ends you can establish a taper from end to end. When you have roughed out the exterior, use a saw (band-saw works best) to cut the Didj in half length wise. Firmly secure the two halves to a work surface with the interior portions exposed. I use a tool called Lancelot from, yes you guessed it, King Arthur's Tools Tallahassee FL. Lancelot is a 4 1/2 in chain saw attached to an angle grinder and turning at 10,000 RPM, it eats wood faster than a thousand starving Beavers. This process can be performed with router and a half round router bit or a hand chisel. Clean out the center material remembering the two sides should resemble half of a hollow cone when complete.
Termites do not eat the interior of a Didj perfectly clean and even - why should you/ Leave the interior somewhat obstructed. It is helpful to scribe a line the same distance from each edge to insure that the amount of wood removed is approximately the same in both halves. Also measure the thickness of the walls before the two halves are joined so that you will have an idea as to how much exterior wood can be removed.
When the insides is complete, apply glue to the halves and clamp them together. This can be done with C clamps or strips of rubber inner tube. When the glue has cured, you can do any final shaping of the outside, sand, decorate and finish the Didj. Depending on the glue and tools you have to work with, you can play your first drone on this Didj the same day you begin it's construction.
It is helpful to scribe a line the same distance from each edge to insure that the amount of wood removed is approximately the same in both halves. Also, measure the wall width before the two halves are joined so that when your are shaping the outside you will have an idea as to how much exterior material can be removed.
Do not become attached to any piece of wood until you have completed the interior and exterior shaping because a number of things can go wrong if you are not careful.
This method comes from the techniques use to build Cedar Strip Canoes and hand built Bamboo Fly Rods. In order to utilize this method you need access to a saw with which to cut strips of the required thickness and a method of tapering each strip so that the each strip is about twice as wide on the Bell end as on the Mouth end. You will cut a number of long (39 plus inches depending on the pitch of the finished Didj), strip of wood which will be glued together side by side around a mandrel.
Create a mandrel. Obtain two or three threaded rods. 5/8 or 1/2 inch rods will form a sturdy mandrel which does not bend very much. You will want about six feet of total rod to build a five foot long Didj. Join the rods using threaded rod couplers. These are elongated nuts into which the ends of rods will screw. Determine the circumference of the mouth end and the bell end (I use 3 in bell and 1 1/2 mouth) and cut a wooden disk. The Didj can also be constructed with Bell and Mouth ends of the same size. If you prefer a wide mouthpiece cut the mouth end disk in an elliptical shape instead of round. A starting point for a wide mouthpiece may be to wet your lips and press them to the wood to get an idea for the initial shape. When you have your disks cut out, drill a hole in the center of the scrap wood disks and attach each to rod about 6 in. from the ends using a washer and nut on each side to hold the disk firmly in place. The 6 in. pieces of extended rod are used to mount the mandrel in a cradle which will allow working space all of the way around the Didj. The cradle is an 8 ft 2x4 with two uprights about 6 in. tall with notches cut in the end to hold the threaded rod and then attached to the base. Attach two wood strips or strings between these two pieces on opposite sides of the disk from each other. At approximately the center measure across and use these measurements to create a third disk to be attached at approximately the center of the rod. This will be the mandrel upon which you will assemble the strips to form the Didj. Using the bell circumference, determine the number (depends on the width of each strip) of the strips necessary to reach around the circumference at the bell. Divide the number of strips into the mouth circumference to determine the width at the mouth end of each strip. Lay out these measurement on each strip in preparation for cutting the tapers. Using a saw (band-saw works best) cut the tapers one on each side of each strip. This sounds like a, forever task, but you will only be working with between 8 to 12 strips (depending on the width). The results will be a number of elongated triangular strips which are about 1/2 half as wide on the Mouth end as on the Bell end
If you decide to make the Didj the same size on both the Bell and Mouth ends cutting tapers will not be necessary.
It is possible to create twists and turns in the finished Didj.
To produce a straight Didj, be it the same circumference on both ends or large on the Bell end the instruction call for construction of a mandrel with three disks with mounting holes drilled in the center of each disk. If you would prefer a Didj that has a little more "character" containing bends or twists, it will be necessary to create a mandrel which allows for these features.
Unless you have fairly developed woodworking skills you may want to consider building your first Didj with both ends the same using this method. This type of Didj requires fewer cuts and a minimal amount of hand fitting. This accomplished you can proceed to flared bells and bent and twisted Didj's.
The creation of bends and twist will require more hand fitting of the edges and depending on the severity of the bends it may require steaming of the individual strips in order to complete the bend without breaking. If steam bending is necessary because of the severity of the planned bend(s) it will require the production of steam which can be directed toward the places along the length of the strip to be bent. This can be as simple depending on the severity of the bend as putting on the tea kettle and holding the strip in the steam from the spout.
With all of this in mind, in order to create the necessary mandrel, rather than drilling the holes used to mount the disks directly in the center of the disk, we will offset the holes away from the center. You must visualize where along the length of the finished Didj you wish to produce a bend (or several bends) and the severity of such bends. With this picture in mind a rough sketch may be helpful. If it is your desire to produce a gentle "S" shape, the disks with the offset holes will be mounted on the mandrel with the major portions of the disk on opposite sides of the mandrel from each other.
In using this technique it is recommended that you add extra disks to be mounted at the start and finish of each curve. This will help eliminate any flat spots in the finished Didj.
Now comes the only difficult part. As you will have noticed by now, when you lay the strips against the mandrel they will butt against each other at the bottom but will leave a gap at the top. This gap can be filled with a number of materials or you can remove some of the wood at the bottom to allow the entire edge on one strip to fit completely against the edge of the next strip. Hence the name " Fitted Edge". The removal of wood from the bottom of each strip can be done by hand or saw. Hand fitting takes forever. The band-saw works much quicker. Test the angle of the cut on some scrap pieces of strips to achieve the correct angles and then cut all of the strips. There will be some minor hand fitting which can be done with a plane or sandpaper.
All of the strips are fitted and laid on the mandrel temporarily before any glue is used. Use elastic or rubber band at the bell and mouth end of the mandrel to hold the strips temporarily in place for fitting.
When all of the pieces are fitted, glue each to the one next to it.
Save yourself some trouble by applying a strip of waxed paper or a coating of melted wax to the wood pieces of the mandrel so that the glue use to attach the strips so that they will not stick to the mandrel.
When the glue is dry, sandpaper, decorate and finish the exterior wood prior to the removal from the mandrel. When all of the exterior is finished unscrew the mandrel rod and remove the mandrel.
If you have glued the strips directly to the wooden disk on the mandrel, the wooden disk will need to be cut free. Be very careful not to damage the wood strips when cutting the mandrel free.
Finish the interior and then you are ready to "Didj Away". Cedar strip makes an interesting sound, are inexpensive, easy to work, light and smells great. If you decide to attempt the Fitted Edge method of construction you might consider Cedar for at least one project.
This method is similar to the techniques use to build boats where each strip over laps the strip next to it. This method is similar in some respects to the Fitted Edge method.
You must build a mandrel, cut strips and determine the number of strips necessary to surround the scrap wood bell end piece. Rather than tapering each strip into a elongated triangle you will thin the edge of each strip so that it will overlap the strip nest to it and not be to bulky. Thinning of the edge can be done with a sander, plane, or saw. The band-saw works best. After your have thinned the edges of each strip they are glued to the strip next to it around the mandrel. There will be more exterior work in this method as opposed to the Fitted Edge method.
I hope these thoughts prove helpful. If anyone has any questions, I can be reached at firstname.lastname@example.org