Mujitsu and Tairaku's Shakuhachi BBQ

What I've learned in about a month of making shakuhachi is that there is no exact formula that will work 100% of the time. That's not to say you should just 'eyeball it' without any reference. I generally look at estimates from http://jeremy.org/music/shakutool.cgi (this is pretty good if you get the average bore diameter and wall thickness right). I then compare those with the values from the LaCosse PDF (also good, especially for standard 1.8). Based on some experience and intuition, I decide which one to go closer to. You should drill the holes on the small side and enlarge as necessary to raise the pitch.

Pretty much what it says - for a 64.9 cm flute it would be

hole 1 (measured from bottom end) - (12.1 x 64.9)/(54.5) = 14.41 cm

6.49 cm between each hole

Hole 4 to hole 5 (3.6 x 64.9)/(54.5) = 4.29 cm

Note that the distance between holes, while given as consistent in the formula for other lengths, is usually not constant in my experience; you can see this by observing the placements for the sample 1.8 in the PDF.

1-2: 5.45 cm
2-3: 5.2 cm
3-4: 5.6 cm

I generally scale the distances by a similar ratio. You can find this by dividing the actual numbers given for the 1.8 by the numbers obtained through the formula (5.45 between all four top holes).

5.45/5.45 = 1
5.2/5.45 = .954
5.6/5.45 = 1.027

Multiply the scaling factors (1, .954, 1.027) by the distance obtained through the formula by any length (in your case, 6.49 cm) to obtain 'corrected' values that are probably somewhat closer to actual positions.

You still have to use your own judgment and listen to the flute as it progresses. You could also drill them all equidistant (6.49 cm) and vary the hole size to affect pitch...

Thanks alot guys" I think I got it now.
I'm making an Excell sheet that will have you put in the length and then gives the hole positioning according to LaCosse and also according to Zink. Would there be any interest in such a file?

Stumbled upon this older thread and thought I'd add a bit.

Tuning strategy is a personal thing. Many things influence the position of the holes; aspect ratio, bottom hole diameter, choke point diameter, hole size, wall thickness, bore irregularity. etc. Therefore, one formula will not be ideal for each flute. As Ed mentions, a formula is only a starting point.

For some, it might be easier to have various formulas for each "style" of shakuhachi. Others might prefer a marked elastic band, then "stretch to fit." I prefer to rely on one formula, then adjust depending on the features of each flute. It depends how you're wired. Whatever works!

Ken