Calculations for flute making.

[Shankar]

Hi,
I found a few interesting links on the web for making flutes. Some of these are for making PVC flutes but the same logic can be adopted for bamboo as well. Here are the links:

http://homepages.bw.edu/~phoekje/acoustics/mahome.html
http://www.phy.mtu.edu/~suits/fingers.html
http://webspirit.com/fluteman/book/flute_making_basics.htm
http://www1.ocn.ne.jp/~tuner/indexe.html

As part of a Indian Classical music learning group in Dallas, we tried our hand in making flutes a couple of times. We tried using these calculations and I must say that we were off only be a very small amount.

The Classical North Indian Bamboo flutes are made from bamboo which has very long inter node spacing (anywhere from a feet to 3 ft).

Its been our quest to find such bamboo here in the USA but haven't been very successful so far.
I also realise that there are other flute makers in this forum. Can they share their ways of calculation. Hopefully I'm not asking for some copyright material!

Cheers!
Bansuri

(Baans: bamboo; Sur : Music!!)

[Bamboozle]

The usual formula for a major key is a matter of percentages of the total flute length from the center of the sound hole. That is, after you trim the length of the flute to give the note you want for it's key, lowest note or do in the do-re-mi scale. Measure from the center of the sound hole toward the foot end of the flute to the center of the finger holes. The percentages I use successfully in a different medium from Bamboo are: 44.74%, 52.74%, 60.38%, 68.22%, 74.93%, and 84.10%.

If the flute measures 12 inches from the center of the sound hole to the foot end, the center of the first hole from the center of the blown hole is 5.3688 inches. 12" x .4474 = 5.3688 inches. In metric measurements, inches x 25.4 gives mm, so 12" x 25.4= 304.8mm and the first finger hole is then 5.3688 x 25.4 = 136.37mm.

Start by making the farthest hole from the blown hole first. 12" x .8410, or 10.092". Convert to mm as noted above or convert the decimal number to 16ths by first subtracting the 10 which leaves .092" and multiply by 16. And 0.092 x 16 = 1.472 16ths. Which I would round off to 1/16".. So, the hole farthest from the mouthpiece is 10-1/16".

Make the hole small at first, then enlarge the hole a very little bit at the time, sounding the note and watching the tuner after each hole enlargement if needed, until it is tuned to re of the do-re-mi scale. Make the third note, mi, next, using the same procedure. Do this in sequence all the way up the bore of the flute until you have all 6 holes tuned to your satisfaction.

If the holes are smaller than desired, either enlarge the hole on the side nearest the foot end of the flute or on the next flute fudge the measurements closer to the foot end by 1/16" to 1/8". If the holes are too large, measure holes for your next flute 1/16" to 1/8" closer to the head end of the flute. Bear in mind, this procedure works for me in a different material than Bamboo.

I'm just starting to harvest Bamboo, so I have to learn to work with the new flute making material. I'll begin with the same formulas as above and play it by ear. (pun intended)

Happy fluteing.

Edited 03/25/05
Allow me a slight correction of the next to last paragraph where it says, "If the holes are smaller than desired,." After you have enough flute making experience under your belt you'll reach the point where you can tell (BEFORE the tuning for a hole is complete) that the hole is going to be too small to accomplish 2 or 3 flute making goals. When you see that is happening begin to tune the hole larger at the downwind side of that hole. THEN, if it happens that you get the hole near the desired size before the frequency is perfect, trim the hole size a bit larger on the mouthpiece side of the hole until the tuning is correct. I make this slight procedure correction because if you tune the hole to the exact frequency first as stated above, then decide to the enlarge the hole (even on just the downwind side of the hole) you will make the tuning for that hole sharp in frequency.
End of edit.