Building a PVC Fujara

(see also 3 minute overtone flute video)

This page will eventually contain instructions for the building of a Fujara-type bass overtone flute from household materials similar to the one pictured left and featured in the second part of the video. For now I'll link to it from the 'Help me' page.

In the meantime I am pasting in my response to a question on the junkmusic group from Tony Hedgewolf (see Tony's drum-building article)

Sent: 02 January 2007 12:10
To: junkmusic@yahoogroups.com
Subject: [junkmusic] PVC and such>

I've started building my waste pipe Fujara - it's got a lovely tone already (although I still need to learn more about fipple cutting !) and just needs holes and a hose. Do you have any suggestions for the hose part ? I've used the 'quick and dirty' split-ring and bung fipple, using a retired demi-john cork, by the way..

I had to devise my own way for overcoming this issue with thin-walled PVC and it remains an area of continual RnD refinement for now. It's not strictly part of my paid work so I can't spend loads of time on it yet although I'm self-employed and temptation....

I'll try to explain what I do but I suspect that a few pictures will be a couple of thousand words worth!

Basically, you need to make a 'angled' fipple plug (5-10 degrees off horizontal) but the 'angle' does not extend to the input end as it would if you were to end-blow it like a pennywhistle. So your plug has the front angled but the back is solid to act as a stopper (in a trad fujara the windway hole extends to the end of the tube and they block it with a small piece of leather). With me so far?

The air comes into the opposite side of the tube from where the fipple is cut. If the flute is lying flat on a surface with the fipple uppermost, the entry point is from the underside and some way back toward the blocked end of the flute. Tuning in the upper overtones can be sensitive to this distance (research a little about plug positioning on transverse flutes although it's not exactly the same effect) and don't forget to give the very exit of the fipple plug a 2mm chamfer (45 degrees) this creates a slight 'curve' in the windsheet and improves tone

To allow access for the air to the windway, you need to drill a hole through the *tube and fipple plug together* from the underside so that when you insert the tube, the air can enter the flute and then can only exit by passing through the windway / edge arrangement. Make sure the input tube isn't butted against the top of the inside of the intrument tube, I generally take a wee sice out of the input tube where it pokes through the inside of the fipple plug to allow the air to exit smoothly, or drill two differently sized holes so the input tube butts against the inside of the plug.

Because the fipple plug positioning in relation to the window determines a lot of the tonal output, you will need to juggle the overall length of this plug design (where I am at now) so that it satisfies both the 'transverse stopper' and windway/edge elements of the positioning. I've in part dealt with this by making the hole through the tube into a slot allowing me some adjustment for fipple edge positioning. When I get that right, I'll start messing with the 'transverse stopper' (for want of a better description)

The construction of a fujara fipple is something that I am still refining but I am somewhat advanced in my workings.

Here are some points to note, bullets save me lots of typing and I'll be happy to try to clarify.

• The ratio of instrument tube's inner diameter to length should be around 50-55:1 to get the proper overtone relationship
  
• The size of the gap where the windsheet exits the fipple plug will largely determine the blowing pressure and the efficiency of the flute (the breathing tube length and its diameter also affects) It should be the width of the window but the height is likely to be just 1-2mm high.
  
• The window (between the sharp plastic edge and where the windsheet exits the fipple plug) is longer than it is wide (i.e the longest dimension is along the length of the tube.)
  
• A fairly standard window width for a 1.7m (G) instrument with 40mm OD (1.5") tube is somewhere about 10mm wide and 12-13mm long
  
• The angle of the plastic edge should be shallow i.e if the flute body is laid horizontal, the edge angle is about 5-10 degrees down and the flattening extends quite a ways along the body of the instrument
  
• The edge should split the airstream approximately 50:50 but you can err on the side of having more air into the tube than out.
  You will therefore need to be conscious of the angle of the fipple cut and how that directs the windsheet onto the opposite angle of the edge, this is more diffiult obviously with no direct visual sight line.
  
• The window gap between the sharp edge and windway really needs high (3-4mm) vertical walls to focus the air. You can do this in thin walled tubing by glueing slices of tube material over the window, building up the requisite height and trimming to requirements.
  
• Don't have the breathing tube too long - it greatly increases backpressure
  
• Condensation will form quickly in the breathing tube - my current design priorities haven't allowed me to work in a spit valve or spit collector yet - Be warned!!!!!.
  
• When making holes be aware that most hole positioning calculations (percentages) assume that you are using a thicker tube than the 1.5 or 2mm of standard plumbing. I have been finding commonly that the bottom (83%) hole is generally slightly sharp.
  
• It's not necessary to place the holes exactly like a fujara, you can put some on the back if that suits your whim or physiology - I do this for my left thumb on some designs
  
• It's not necessary to use standard penny whistle hole positions - consider using a NAF pentatonic positioning (not exactly sure how this affects only 3 holes though)

Ok so it's not 2000 words (but gets closer every time I re-read it!) but I hope that it starts to explain a little of the balancing act that goes into making all these kinds of instruments Tony. I left my camera at a friend's house on NY eve but I'll take some photographs when I get it back in the next days or so.

As I said, despite having built hundreds of flutes and whistles, the construction of fipples is something that I am still refining although I am making progress through direct and applied research. If there are any professional builders here who can advise me on the finery of edgetone mechanics I'd be delighted. I have books & research material on organ and flute building that tell me *how* to build X and do give some reasoning behind variations, but I'm looking for one that helps me *understand* how the various factors interrelate, e.g the relationships between the window length and width, wall height, windsheet dimensions, cut angles etc etc and anything which can give calculations or (simple) formulae for working out optimals in all of these would be brilliant (I'm waiting for Fletcher & Rossing's 'physics of musical instruments' to arrive as I type).

A day without learning is a wasted day

Paul
____________
Paul Marshall
noise and stuff

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