Finishing the Pan Flute

After cutting the rough lengths you must finish off the blow end of the tube by filing or sanding a radius on it with a sharp edge on the inside. Make this as smooth as you can with fine sand paper. leave the edge on the inside sharp, as it is shown in the photo at left. One other step to go with the individual tubes before assembling and that is sealing the blow end. Use the hot paraffin again on this newly sanded end. Keep it in the hot paraffin until it bubbles, like a french fry in the hot oil. Don't cook it, but let it bubble for a few seconds to get the moisture out. As the water in the bamboo boils out, the paraffin will replace it during this process. Making the otherwise porous bamboo, moisture resistant.

Lets look at what we have now:

1. We have all the tubes we need, rough cut to with in a half inch of the proper finished length.

2. Both ends of the tube have been rounded over and sanded smooth, making sure that this process, on the open end, does not take the sharp edge off the inside diameter.

3. The ends and the inside of the tube have been sealed with hot paraffin.

4. All of the pipes will sound a note that is flatter (lower) than it is supposed to be, by a half tone or so. I like to leave the fine tuning until after they tubes are assembled in to place.

Assembly is next. At left is the simple binding method. I used nylon twine and a criss-cross pattern. The cross members that the tubes are tied to are made from splitting a length of bamboo and filing or sanding the inside till it is only around 1/8" thick. The flexibility of this cross tie is important in securing tubes together of slightly different diameters. If this piece is too stiff to conform to a smaller tube between two larger tubes then your assembly will not be as strong as it could be. Notice the pattern i used to ties the tubes. Criss-cross on the tubes and straight wrap between them. giving an X|X|X|X|X looking pattern. Although this is the simplest assembly method, it is tricky to get it started and when you are finished your hands will ache from the labor.

The good part about the method of assembly shown above is that you do not need any thing other than what you see in the picture. The tubes, the cross pieces, and the string. No tools required. Although i did use a large needle to thread the string between the tubes. There are other methods of assembly that require the use of jigs, or devices to hold the tubes in place while you secure them in that position by what ever means you decide to use. Here are some examples of assembly jigs that i have used to make pan flutes.

Here is an example of a fairly simple jig for assembling a curved pan pipe. The dark lines you see going across the little vee shaped notches is rubberized fabric cord. You pull it and it stretches, let it go and it snaps back. I insert the blowing end into the notch with the cord pulling it firmly into the Vee. That way i can hold the pipes in place while i bound them. In this case i bound them with jute twine and omitted the cross braces by coating the twine with a 50% mixture of white glue and water. This soaked up into the jute and made it stiff. The resulting pan pipe is very strong and sturdy.
Here you can see how the elastic cord is woven between the peaks of the alignment Vees. These holes go all the way through the jig and out through the other side, to loop back through and out of the peak again.
The band stretches as shown above but it does not hold too tightly and care must be used when wrapping, not to disturb the alignments of the tubes nor let them fall out of contact with the alignment surfaces of the jig.

The pan pipe below was made on the jig shown in the photo above right. The second row of tubes were added later on to create a chromatic instrument that can play sharps and flats as well as the general notes of the "D" scale. This particular pan flute is tuned to the key of "D" which is a popular fiddle and mandolin key due to the open string positions on those instruments.

Using this type of construction gives a very strong pan pipe, practically indestructible. You could use it as a weapon and play music with it afterwards. I used a special wrap when binding the tubes together. I would wrap two tubes forward and one back. That is each time made a loop it went around three tubes, then back only two tubes, and ahead another three tubes, and so forth till i had the set completely wrapped. Then applying glue and water i made it solid. When the glue was dry, i put a few coats of varnish on the jute twine to seal it and make it smoother. Jute is rough stuff and does not have a pleasant feel to it untreated and dry. Light sanding was used too.
At right you will see the back side containing the second row of pipes. These are arranged just like the black keys on the piano, except in the key of "D" configuration. These tubes are attached almost the same way except only one criss-cross pattern and one straight bridge loop was all i had room to use here. Actually i did a bit of over kill on the main body of the pipe. Only a couple of bands in two or three places would have held up ok. But this was the first bamboo pan flute i ever made and we live and learn. The more mistakes i make, the more i learn. Hopefully if i screw up enough i'll eventually be pretty smart. any how this is another way to bind the pan flute tubes into place using a simple assembly jig and glue.

When making the pan flute from PVC pipe, you don't have to bind the tubes at all. I guess you could, if you wanted to but it is so much simpler to just glue them together with PVC cement. This stuff partially melts the PVC material and then lets it fuse back together again, against the next tube. The cement dries very quickly but a pipe made this way could never be "dropped" or it would break apart into how ever many pieces.
The nice thing about working with PVC is that you can cement the tubes together and not have to tie them at all. It makes life simpler I also used cross pieces cemented on after the pan pipe was assembled. The cross pieces although thin, do add a measure of strength to the assembly. It one were careful and used caution handling this type of pipe the cross braces probably would not be needed at all. This type of assembly does not have the strength of the binding method but it sure saves time in the construction. Also the end caps have to be made and glued on with white glue to close the far end of the tubes.
Using PVC produces a very nice pan flute. To make life even simpler, you do not have to make caps for the bottom of the tubes to seal them. If desired you could make the tubes a half inch to an inch longer than necessary and use a 5/8" diameter rubber or soft plastic plug in the far end. This would also provide a fast and easy way to tune the pipes. Pushing the rubber plug towards the open end will raise the tone of the tube, and driving it back away from the blowing end will lengthen the resonating air column and make the tone lower. See the photos below of the very first pan pipe i ever made. I constructed it from stainless steel tubing with a .450" inside diameter. I drilled 1/2" diameter holes in a piece of high density plastic foam material and inserted the tubes, using white glue to fasten them inside the holder. I then cut a bunch of soft plastic plugs to fit tightly into the inside of the steel tubes and plugged all the far ends, closing them off and providing a means of tuning the pan flute.

Stainless steel tubes with plastic tuning plugs

Stainless tubes and plastic foam body
Soft plastic plugs provide a way to tune the instrument

Getting back to the bamboo pan flute construction lets take a look at a little more sophisticated assembly jig. I got a little fancy with this one. It has many moving parts and individual pieces involved in the assembly. This jig has the Vee's located at 7/8" centers. So the tubes that you use to make the pan flute can not exceed that outside diameter. The closer the tubes are to that size the better looking instrument you will have. If you use tubes that are too small in diameter then there will be a big space between each tube, however all the tubes will be spaced out in identical distances, making the playing of the pipe more linear and uniform.

This jig has two wheels and capstans that wind up the nylon twine loops and hold the bamboo tubes firmly in place for assembly. The two wheels have 6 holes in them and each wheel has a little peg that is used to hold the tension on the nylon loops. The nylon twine is one continuous length of nylon with the ends wrapped around the capstans and passing over little pulleys inside the jig. The twine goes from the pulleys through holes in the peaks of the Vee's and down into the hole in the next vee to pass again around the next pulley. Going on this way for the length of the jig.

You can see below left the nylon twine being taken up by the capstans in the bottom of the jig. On the right hand side you can see how the pegs are inserted into a hole in the wheel to anchor the wheel in that position, keeping the nylon taut and the tubes firmly in place.
Assembling a set of pipes using this jig has advantages and disadvantages. The advantage is the rock solid positioning of the tubes. You do not have to be careful binding them when using this jig because they will not move. Another advantage is the tubes have all the exact same distance between them. It does not matter how big (as long as it is not over 7/8" dia) or small the tube is, the distance from it to the next one will always be the same. This makes playing it easier and more linear. The disadvantage is that if you use tubes of too small diameter you will have large gaps between the tubes. This could be an advantage if you are planning to make the pan flute into a chromatic model. You need the wide separation and free air space between ranks of tubes. The spacing is actually 7/8" between Vee's on this jig. The optimum diameter pipe to use would be between 3/4" and 7/8" diameter. This would make a very nice looking pan flute. I spaced the Vee's that far apart because the diameter of PVC 1/2" pipe is .850" outside diameter. The decimal equivalent for 7/8" is .875" so this would be a good spacing for plastic pan flutes as well, but using the binding method rather than the gluing method. Or perhaps some method i have yet to discover. I find out new things every day.

You can see at right the under side of the assembly jig. There are two rows of small pulleys mounted on common axles. These reduce the friction on the twine during the tightening of the crank wheels. It is difficult to see in this shot at right but the line weaves over the pulleys and back up through the holes, over the Vee and down the hole of the next Vee, to once more pass over a pulley and back up for another loop. Each crank controls every other vee position. For example all the odd number of Vee's are controlled by one wheel and all the even numbered ones are tightened by the other one.

When tying the bamboo tubes to the cross braces i use a large needle to thread the twine in and out to make the criss-cross pattern that we are aiming for. Using the needle will greatly speed up the operation. Especially if you are using tubes that are nearer the large limit in outside diameter because they produce the smallest gaps between the tubes.

You can see at left, that i have already attached the first cross piece and have moved the tubes out a way from the jig body so i can put the second brace across the tubes, a little lower down. It will go about in the middle of the middle tube. Using the criss-cross pattern i will attach the middle brace and then relocate the pan pipe with the blow end held under the loops in the vee's and put the shortest and last cross brace on to steady the longer pipes. See the photo at the top of this page to see how i have laid out the braces on Rui's pan flute. The flute you see at left is going to be living with my friend Stitch, in Manitoba, Canada, when it is finished.
Continuing this way you will get all the cross braces in place and secure your pan flutes strength. It is light but strong now. Now comes the final step in the construction. After filing and sanding the cross piece ends to make them look good, you must do the final tuning of the pipes. This will be done using the hot paraffin again. keep plenty of paper towels on hand to wipe the excess wax off the pipes as you spill and splash your merry way though this next step. You will either have to be blessed with perfect pitch, or you will need some help on this step. The help i use is in the form of the Sabine ST-1500 electronic tuner. It is palm sized and runs on a 9 volt battery or ac power.
There are many electronic tuners on the market today and this is just one of them. What i like about this tuner is that you do not have to select the note on a dial because it is automatic. Just sound the note and a little red LED below the closest note will light up. Also one of the three LED's on the top will also light and flash. The frequency of the flashing will indicate how close you are to being on the correct pitch. The left top light means the tone is low and the right top light means it is too high. When you get it right, the light in the middle of the top, the green one will light up. As you bring the tone closer and closer to the proper pitch the rate of flashing of the high and low indicators will slow down. At the point where the flashing would stop the green light comes on and you know you have the pitch correctly set.

Fine tuning the pan flute

Get the paraffin pot on the fire again and heat up the paraffin. This is what we will use for the final tuning of the flute. The shorter the tube, the higher the pitch and we made all of our tubes just a fraction of an inch longer than necessary so we could have some measure of flexibility when tuning the instrument. By pouring tiny amounts of the hot paraffin into the tube you actually are shortening it musically. Pour a small amount of the hot wax into the tube and test the pitch by sounding the note and observing the electronic tuner (be careful not to burn yourself on the hot wax) . If the pitch is too high, then quickly pour out some of the wax and try the tone again. When the pitch is too low, then add wax, if the pitch is too high, take some out. Keep this up until the pitch of the tube is perfect. Be careful to pay attention to how you blow each note. Try to use the same amount of air pressure and angle of air stream when testing each note. It is possible to mistune the tubes by not giving paying attention to this aspect of the tuning process. If the pitch is too high and the wax has solidified already you can melt some out by heating a metal rod and putting it into the tube so it comes in contact with the hardened wax. If you have given enough attention to the embouchure and air pressure when tuning the pan pipes then you will not have to make any further adjustments. However i have found that i seldom get it right by tuning individual pipes. I must play some tunes on the instrument to be sure. When actually playing on the flute, i do not necessarily use the same embouchure and if any of the tubes are either sharp or flat, then it will show up when you are actually playing music upon the pan pipes.

Well that is all there is to it. Have fun and if you have any problems you can always drop me an email and i will do what i can to help find an answer for you. my email address is on the home page.

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