Another flute problem is the tendency for upper register notes to be flat unless blown hard. I solved this by placing the note holes so that less pressure is needed to blow the lower register on pitch. These notes don't blow sharply, they blow easily. When transitioning to the upper register, blowing normally -- if a bit forcefully -- gives a normal pitch instead of screechy high notes. The compromise here is to be aware of the design, and adapt slightly when playing.
Naturally a flutemaker benefits from being a flute player, multi-instrumentalist, woodworker, and mathematician as well. But I have run into trouble by being too much of one thing at one time. For instance, the science type who is not a player will subjectively blow a note with just the right force to center the meter on an electric tuner. This is fine for one note, but if all the notes require a different force to blow on pitch, the flute will be tough to play.
Conversely, a player with no regard for science might play a flute which is somewhat out of tune, and make it sound good. But it is still an out-of-tune flute. So I set a parameter -- position each note hole so that the same low force of breath will produce notes in pitch in the lower register. This means making a prototype flute, plugging the note hole and drilling another more accurate hole. Using math to determine hole position is a good departure point, which says my math is not the best. But ears and breath determine the fine tuning of note hole position.
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