Undercutting tone holes.

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Undercutting tone holes.

Postby bob Salter » Thu Jan 03, 2013 7:23 pm

I must confess to major frustration with undercutting tone holes. I have tried unsuccessfully several times to 'improve' the tone of a chanter by undercutting towards the bottom end of the chanter. The 'improved' chanters ended up in the firewood pile.
Today I went back to basics. I made an f+ chanter from the measurements in the Dave Burleigh section of this site. I plugged the keyholes with sticky stuff. Result, a chanter that plays beautifully in tune, possibly the best result I have ever had, it would only require very minimal tuning with the manometer to get it great.
However, I cant help but feel I am missing out on something tone wise. I'm not sure what, it sounds good to me, but something.
Is undercutting necessary? Any ideas what I might be doing wrong? I will now add keys to the chanter and I guess make another to the same drawings. Then I can test out the differences it makes.


Bob
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Re: Undercutting tone holes.

Postby andymay » Fri Jan 11, 2013 3:01 pm

Bob,

Yes it is.

Undercutting takes away the sharp edges to the holes which cause turbulence and effectively make the holes act smaller than they are. Think of it like a cylinder head or something like that - sharp edges = bad, inefficient, loss of power. Smooth edges = good.

In real life if you don't undercut the holes a wee bit you'll probably find

1. Some notes sound a bit whistley
2. Opening a vibrato finger makes a lot more difference than you'd like - sounds pretty grim usually.
3. Even with a v lively reed, the chanter's not that loud.

(To some extent i suppose the size of your holes has a bearing on this - if you make the holes very big, then maybe it won't make much difference.)

You can investigate this a bit by opening some more holes whilst you're playing (not that i would ever suggest doing that of course for fear of incurring the wrath of Tom Clough's ghost who would immediately bludgeon me to death with a railway sleeper)
But if for example you're playing the C note and wondering how it would sound with some undercutting/a bigger hole, try opening the B hole as well and have a listen. It's a crude mock up but it gives you the idea.

It's interesting that Benade reckons historically clarinet makers used to do as we generally do in terms of tweaking/undercutting tone holes to bring an instrument into tune. Then they began to employ more modern techniques and accurately drill the holes in the correct place and up to size with pristine sharp edges. Then they all wondered where the tone had gone....

How did your undercutting previously go so badly wrong as to render the chanter firewood?

A
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Re: Undercutting tone holes.

Postby Francis Wood » Fri Jan 11, 2013 4:27 pm

I agree with Andy's expert explanation and would add only one thing. Over-cutting is also important - I don't know if the term exists but at least it does now!

What I mean is the slight rounding of the tone- holes at the surface of the instrument. A crisp edge may look very smart but in acoustic terms, is inhibiting of good tone. Benade refers to this practice too.

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Re: Undercutting tone holes.

Postby Richard Evans » Sat Jan 12, 2013 11:15 am

bob Salter wrote:I must confess to major frustration with undercutting tone holes. I have tried unsuccessfully several times to 'improve' the tone of a chanter by undercutting towards the bottom end of the chanter. The 'improved' chanters ended up in the firewood pile.

Bob


Can you describe what you a doing? I just undercut towards the foot of the chanter using a dremel drill, easy and quick. Andy's comments on the benefits are spot on.

Cheers
Richard
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