World Shakuhachi Discussion / Go to Live Shakuhachi Chat
You are not logged in.
I recently got a beautiful piece of Chinese Madake from Monty for making a cast bore 2.4 flute. The piece I received was much longer then that, so I decided I would try making a 3.3 jinashi out of it first and if that didn't work out I would go ahead and cast the bore. Well, tonight I started working on the flute and I hit the same problem I have encountered with my other attempts at a long flute. Otso ro is weak. Pushing it even a little jumps it into kan. Kan plays nice and strong and even daikan is decent. What areas should I be looking at to get my long flutes to have a stronger otsu ro?
I will add that on other long flutes I have made, it has only been otsu ro that is weak. Tsu and above play just fine. I haven't drilled any finger holes on this flute, and don't plan on it unless I can get this issue worked out.
What bore diameters have you opened, blowing end, bottom end, choke ?
also, depth of your utaguchi.
Just a note, I am blind so images are not useful to me.
What is Ro kan and dai kan like ?
Have you cleaned out all of the membranes ?
I am still working on cleaning out the membranes.
The blowing end is opened to 21mm currently. The inner diameter looks to be 23mm.
I haven't had time yet to work on the bottom end. The opening through to the choke point is 17mm.
The length of the flute is currently 99.6cm.
Utaguchi width is 16mm and the depth is 3mm.
Ro kan and dai kan both sound clear and strong to my ears.
Some overall theory might be of use. Have a look at this link, especially down around figures 5 and 6:
And then some more, in the first ten or twelve links here:
http://www.google.com/search?q=navachin … =firefox-a
Seems as though your issue may have something to do with aspect ratio. You've got a very high one, which favors the high end at the expense of the low end.
There may be a turbulence issue regarding hard edges on remaining membrane ridges, clearing these and opening the bottom could help.
I also agree that the aspect ratio is not helping, if the length was shortened the aspect ratio should promote a stronger Ro in otsu.
If you pull your lips back from the utaguchi edge, does the Ro improve ?
I'm with Ed and Kel also. That bore width would work much better on a 2.4 than a 3.3. There is a relatively wide window for aspect ratio (check out Ed's links) but that goes beyond the limit. Too thin and the bottom end suffers. Too wide and the top end suffers.
You may be aware of this but bamboo for shakuhachi are often harvested with an extra node or two. This makes it handy should the maker decide to cut part of the middle section out to make a two piece flute.
Can you still make a 2.4 out of it?
Yeah, I can still go for the smaller size. I wanted to try for a big honker if it would work. I will spend the weekend going through Ed's links and play around with the full length before cutting it down.
Thanks for the input.
Getting rid of the contractions at the membrane points will certainly help, but 23mm is definitely on the thin side for a 3.3. OTOH if otsu tsu is not too bad, ro shouldn't be that much worse. I have spent a lot of time making sure that the membrane points are not only smooth, but also close to the same diameter as the main body tube. You could also consider opening up the choke point somewhat.
Last edited by Toby (2010-12-07 05:08:50)
I now have the flute cut down to a length of 788mm. After some more work on the interior, Ro is now sounding much stronger. I have a bit more I want to do on the bore, but I hope to start drilling the finger holes this weekend. I
I will throw my hole placement question here as a starting point.
On this page
he talks about hole placement on flutes longer then about 2.2. Standard placement on the one I am making is a bit of a stretch for my hands. Does anybody have any experience with doing placement as mentioned on navaching?
Some thoughts, sounds like you have perhaps a 2.6 or so and may require only a slight offset of holes 1 and 3, your 'ring' fingers but may I suggest you keep this to the minimum. with use you will find the reach gets easier.
You could drill holes 2 and 4, your index fingers to give you the relative posture for holes 1 and 3. Holes 2 and 4 do not need to be offset.
You could leave the thumb hole undrilled at this time, or drill that but you may also want to offset that too.
Holding the partially drilled flute in good posture, mark the locations where fingers 1 and 3 sit , same length from the utaguchi as they would be if in line, but offset perhaps no more than 5mm.
Is this what you are asking about ?
On Navaching, he talks about using a hole placement on longer flutes that have a span not greater then 25cm. I decided to give your off set suggestion a go this morning. I laid them out and test drove them before drilling. Hole placement felt fine so I jumped into drilling the finger holes.
I have started slowly opening the holes. I still have a long way to go, but I am now noticing that otsu Ro and tsu are becoming quite unstable and easily jumping into kan.
Here are the measurement of the now shorter flute.
The inner diameter at the utaguchi is 23mm.
the bottom opening is 20mm.
Choke point is about 18mm
The length of the flute is currently 78.8cm.
Utaguchi width is 18mm and the depth is 3mm.
I just through my utaguchi angle jig on it and the bevel may be a bit on the steep side, but certainly within the realm of what I have seen from some makers.
Have you opened the thumb hole ? Did you offset it at all to suit your posture ?
Sometimes getting used to the longer reach we do not fully close the holes adequately, particularly the thumb and the note breaks.
Give it a bit of time as you get used to the posture and grip.