Mujitsu and Tairaku's Shakuhachi BBQ

Aesthetically, if for no other reason, it should go the way it grows, since there is a "ball-in-cup" type configuration to the outside of the nodes. Acoustically, generally the inside diameter increases from the root end through a number of nodes, then becomes constant for a while and eventually decreases as the branches and leaves start to appear. Best is for the diameter to decrease towards the end, and this will happen if you use the lower nodes (even without the root end). You definitely do not want it to increase towards the end, as this is disaster for the second octave.

You will also notice that each node is at a slight angle and this alternates from node to node.
Aesthetically you want the curve to face upwards on the front of the flute.
Getting a perfect culm becomes more difficult to conform to all of the conventions.
With a perfectly round culm the utaguchi and finger holes could be placed on any side, but if the culm is oval, even slightly then it is more comfortable to place the utaguchi and holes either on the side or top of the oval, not on the diagonal.
Regarding the slope of each node, the aesthetic is to have the utaguchi on the upper side of the slope.
All of this requires the culm to have grown in such a position that the 'front' side curves slightly towards the sun.

K.

KibaXIII wrote:

ooh, thank you muchly Toby!  is there any corespondence to the bend of the boo and the utaguchi's placement in the shakuhachi's sound? say for instance the boo bends out slightly and the uta is aligned at 0 degrees opposed to 90, 180, or 270.

The utaguchi angle is measured relative to the bamboo walls at the top, not to the overall curve of the culm. Even the most radically curved bamboo is not going to affect the sound appreciably, though FYI a toroidal bend has the effect of making the bore appear shorter and wider to the air column. I could give you the mathematical formula for determing this, but trust me, it doesn't make a bit of difference practically.

While convention always has the curve facing out, let's not forget that basset horns are curved the other way, and in fact I made a very nice 2.6 that curves in the wrong direction (because of the angle of the top node).