Native American Flute Design and Construction - edwardkort/WWIDesigner GitHub Wiki

I thought it would be informative if I laid out the design steps I use in creating a NAF. It is my hope that WIDesigner makes many of those steps much less painful and more accurate. Text in bold represents activities to be performed with the aid of WIDesigner.

In brief:

  1. Specify the key, sound mechanism, head space, fingering pattern, and bore diameter at the foot of the flute.

  2. Using playability constraints, iteratively perform layout calculations for bore taper (position and slope) and finger hole position/size.

  3. Craft the flute without finger holes. Measure the as-built bore profile and wall thickness. Voice the flute and measure sound mechanism parameters.

  4. Recalculate hole layout.

  5. Tune the flute.

Initial Specification

  • Key: the NAF, because it has such a limited tonal range (typically an octave plus a third), is made in keys from A2 to A5. The design "sweet spot" is F4 to Bb4. Outside of that range, because the NAF is a keyless instrument, hole spacing raises issues.

  • Sound mechanism: this includes flue/channel shape and flue-end type. This geometry allows the production of various tone type (bell-like [odd-number harmonics] or more complex tones), volume, and tone quality (clean or breathy). The various geometries have a fairly dramatic effect on instrument layout and tuning.

  • Head space: flutes with larger head space are easier to play, and the overblown octave can be tuned by the length of the head space. However, the second-octave notes become much more difficult to tune.

  • Fingering pattern: there are a relatively small number of "formal" fingering patterns for the NAF. I consistently use one that encompasses the chromatic and second-octave notes.

  • Bore diameter at the foot: this value, independent of bore taper, determines the tone quality and timbre of the lowest few notes. Various makers use very different values for the bore diameter. I'm in the "large bore" school.

Pre-construction Design Calculations

In this stage, the bore profile is varied until the finger hole layout and sizes meet playability constraints while maintaining the desired tuning accuracy. Historical data for the fipple geometry is use at the point. It would be very nice to estimate tone characteristics at this point, but I have no software that achieves these calculations.

Finger hole constraints include:

  • Hole spacing between the holes played with each hand: the NAF is usually made as a 6-hole flute, 3 holes covered by each hand. Depending on the intended player's hand size, the maximum hole spacing within each triplet of holes will be between 1.1" and 1.4"; the minimum hole spacing is 0.8".

  • Hole spacing uniformity: there is a standard aesthetic in NAF construction that requires the holes in each triplet to be uniformly spaced. There is no requirement that the spacing of the two triplets are equal, however.

  • Hole size: because holes in the NAF are covered by fingers, holes typically should not have a diameter greater that 0.45". Minimum hole size must be sufficient to cleanly play the notes; software support would help here.

  • Hole size uniformity: there is a less formal aesthetic that requires hole sizes to vary smoothly as you go up the flute - not monotonic changes, but smooth ones.

Because bore taper has an adverse effect on the playing characteristics and tone quality of the NAF, the taper should be as small as possible. To meet the above hole constraints, I have found that a taper that encompasses only the bottom 3 holes works best.

At this stage, I require a calculated tuning deviation from expected of no more than 5 cents. When I tune the flutes, I can reduce this deviation by shaping (by hand) each hole.

Craft the Flute Blank (no finger holes)

In this stage, the flute is made according to the design determined in the previous stage. I make flutes in two, full-length halves. After crafting and smoothing the bore profile, it is accurately measured (hand-made flutes do not exactly match the design specs). Then the two halves are glued together, the outside of the flute is shaped, and the wall thickness profile is measured.

The flute is voiced in this stage. Then, based on the frequency of the tone played and the measured bore profile, fipple parameters (modeled as an embouchure) are calculated. These parameters replace the historical parameters used in the Pre-construction Design stage.

As-Built Calculations

Using the as-built measurements and parameters, the hole layout calculations are redone using the same design constraints.

Flute Tuning

Using the results of the as-built calculations, the flute is cut to length and the finger holes are drilled undersized. Based on the deviations from perfect tuning, the finger holes are shaped to bring all the notes into tune. The pattern of deviations calculated above guides this shaping. Tuning is an art, balancing constant breath pressure with the expected volume increase of the higher notes during expressive play.