tone hole undercut

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LiamO'Flynn
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Re: tone hole undercut

Post by LiamO'Flynn » Mon Dec 13, 2010 6:31 pm

I do find it very interesting ,althrough I have to admit with my level of education find it hard to understand.I find the last paragraph the most appealing which as understand it is say some chanters need loads of work to get them to play right ,others dont.But I think your post will be of great help to those who can understand it
I also want to back-track in the respect that the Davy Stephenson question should have been directed to Mr Gumby,who is always eager to declare his expertise but never willing to demonstrate it.It is his opinion that undercutting is essential ,but the Davy Stephenson point disputes that.

according to Nederveen the jury is still out over the turbulence question,and why do you think I'm trying to"bait" you

Liam
Liam O'Flynn the plumber not the piper .

Jonathan_P
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Re: tone hole undercut

Post by Jonathan_P » Mon Dec 13, 2010 7:19 pm

I certainly do find your observations and suggestions interesting and useful, Bill. Thanks for taking the time to spell out the details so clearly.

I'm wondering what sort of effects can be achieved with a fraising tool. As I understand it this tool would (with a steep enough cutting angle) cut first at the sides of the tonehole/bore intersection before reaching the upper and lower inner edges of the hole. Used in moderation, this would, I imagine, have the effect of enlarging the volume of the chimney without moving the edges up or down.

I have both of the articles that Mr. G referred to from Ceol na hÉirreann vols 1 and 2, and agree that there's a lot of good information there. Do your homework, folks. This information is available from NPU.

And Liam, why don't you ask Mr. Stephenson to come here and speak for himself, if he disagrees?
Jonathan

billh
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Re: tone hole undercut

Post by billh » Mon Dec 13, 2010 7:28 pm

Thanks Jonathan - A fraise gives an approximation of this, though I think there may be an advantage to the "rounder" profile produced by small files and such. One problem with fraises is getting them inside the bore, the other is that the hole size can be somewhat large relative to the bore size in some chanters, so you can't easily get a good even rounding effect, or can't get the fraise high enough inside the bore.

Liam - I am sure my explanation could be clearer. It was more than long enough already, so I had to stop somewhere.

I had another look at Nederveen - his explanation of the different effects of upstream vs downstream undercutting was instructive.

I see that in the 1998 'revised' edition Nederveen inserts the word "supposedly" in parentheses when he mentions reduced vortex losses for undercut toneholes. I take that to mean that it hasn't been demonstrated in the lab. Certainly the principle of vortex losses at sharp boundary edges is not in itself controversial - it's well known in other fluid mechanics fields. The issue might be whether flow in a woodwind instrument is fast enough to be turbulent; I suspect that it mostly isn't, so perhaps I abused the word "turbulence" when I used it above. If the flow is what's referred to as "transitional" rather than purely laminar (which I suspect is correct, based on some rough calculations) then it could well be that the tonehole edge rounding would make the difference between eddies forming or not. Or maybe the effect has to do with flow splitting in some other way, and isn't technically turbulence.

Whatever the underlying cause, you can hear the effect.

As an extreme example, I sometimes use very small tonehole sizes for keyed "high d" and/or "high c#" notes. Often they don't play properly - sometimes they don't sound at all - until I round the edges very slightly, at which point they begin to work. This can happen with 2.4mm holes or with larger holes of 2.7mm, so I don't think it's just because of the "enlarging" effect of the undercut. It also seems to have been my experience that the functioning of a ghost d on a small-holed chanter can be strongly affected by a small edge rounding.

Leaving aside the question of appropriateness, I have very limited experience with Mr. Stephenson's work so I am not in a position to comment on his results.

Bill

Mike Hulme
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Re: tone hole undercut

Post by Mike Hulme » Tue Dec 14, 2010 7:00 am

An excellent summation there Bill. I have just stolen it. :D

outofthebox
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Re: tone hole undercut

Post by outofthebox » Tue Dec 14, 2010 8:37 am

billh wrote: Lastly, one key reason for refining toneholes after drilling (and reaming of the chanter) is that, no matter how careful and consistent you attempt to be, every piece of wood will react to the reamers a bit differently. Particularly in the case of small holed "flat" chanters, the final result is very sensitive to subtle tonehole modifications. Shaping the toneholes by hand, empirically, after fabricating the chanter to an ideal plan, give one the wiggle room required to compensate for these differences and allow the individual chanter's potential to emerge - perhaps quite intuitively, without being able to reduce each stage to an explanation. I don't claim to have mastered this process by any means, but I know that it can and does take place.

Bill
My intuition tells me that Bill's empirical approach points the way ahead. At present there is no perfect model that can be replicated, so every time a chanter comes off a lathe, each maker has an opportunity to push the instrument a little further forward. 8)

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Mr.Gumby
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Re: tone hole undercut

Post by Mr.Gumby » Tue Dec 14, 2010 8:44 am

outofthebox wrote: My intuition tells me that Bill's empirical approach points the way ahead. At present there is no perfect model that can be replicated, so every time a chanter comes off a lathe, each maker has an opportunity to push the instrument a little further forward. 8)
Sorry for getting on your case each time and don't take it the wrong way, but really isn't that the way it has been since Coyne, Harrington and the rest of them voiced their chanters? it's not exactly a new idea, as anyone who has examined chanters by the great makers of the 19th century would know. Local and specific bore adjustments, undercutting and hole voicing and all that stuff has always been the stock in trade of the pipemaker.

It's the sensitivity, vision (with regards to what the pipes should be and how they ideally should sound like) and ear of the one doing the job that 'will push the instrument forward'. But that's an altogether different issue. One that makes the difference between a decent, a good and a great instrument though.

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djm
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Re: tone hole undercut

Post by djm » Tue Dec 14, 2010 9:23 am

Great explanations, BillH. Thx. I understand how you would have to either cut off the explanation or write an entire treatise on pipe-making (which NPU should be doing instead of playing with workshops IMHO). I may be mistaken, but I think you meant "affecting" instead of "effecting" throughout your first post.

djm
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bobble991
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Re: tone hole undercut

Post by bobble991 » Tue Dec 14, 2010 12:35 pm

Thank you Bill. I too have stolen it. I certainly caught the gist of it but I think I will need to read it several more times to fully understand it. Its saved in my pipemaking folder for reference.

Cheers
Bob

Pastorale
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Re: tone hole undercut

Post by Pastorale » Tue Dec 14, 2010 2:20 pm

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Last edited by Pastorale on Wed Jan 19, 2011 9:21 pm, edited 1 time in total.

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bobble991
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Re: tone hole undercut

Post by bobble991 » Tue Dec 14, 2010 3:03 pm

Ehank you for that. Your comments about c# and c natural will be very helpful, as you may have seen in another post I had been having problems in that area. I discovered bore problems which I rectified with a new reamer. I have a much closer c nat to c# now but was a little unclear how to improve it more. Ill give your method a try.

Bob

billh
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Re: tone hole undercut

Post by billh » Wed Dec 15, 2010 10:36 am

djm wrote:Great explanations, BillH. Thx. I understand how you would have to either cut off the explanation or write an entire treatise on pipe-making (which NPU should be doing instead of playing with workshops IMHO). I may be mistaken, but I think you meant "affecting" instead of "effecting" throughout your first post.

djm
Nice catch; "effecting"->"affecting" (one instance); "effect"->"affect" (as a verb), 2 instances. Fixed!

Regarding a pipe-making treatise - talk (read "writing") is cheap, there's no substitute for direct experience...

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KM
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Re: tone hole undercut

Post by KM » Thu Dec 16, 2010 5:22 am

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Last edited by KM on Sun Dec 19, 2010 5:03 am, edited 1 time in total.

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djm
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Re: tone hole undercut

Post by djm » Thu Dec 16, 2010 6:28 am

billh wrote:Regarding a pipe-making treatise - talk (read "writing") is cheap, there's no substitute for direct experience...
Undeniable. However, investigation and published treatise will reach far more people and last much longer than five or ten people who will take the hands-on course and one or two who may actually stay at it. It would set far more people experimenting with pipemaking on a productive path faster, at less expense and far less waste of diminishing materials to have written guidelines on the whats and hows. Note the references to various pipemakers' writings even in this thread. Imagine if NPU were to use its considerable archives and abilities and bring all the many strands and writings together in one well-illustrated manual. Just my thinking.

djm
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Pastorale
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Re: tone hole undercut

Post by Pastorale » Thu Dec 16, 2010 6:33 am

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Last edited by Pastorale on Wed Jan 19, 2011 9:22 pm, edited 1 time in total.

monkeraimac
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Re: tone hole undercut

Post by monkeraimac » Mon Dec 20, 2010 11:50 pm

many thanks to all who replied with constructive advice I will now try to compute what has been written thanks again to all monkeraimac
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