 The Clarinet BBoard
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Author: Avie
Date: 2003-05-29 22:11
I am trying to educate myself on the construction of my clarinet. What is actually meant by the term undercut tone holes? I measured my buffet tone holes and they each taper from the top to the bottom approx .012-.015 on each of the dias. Is the slight taper considered undercut? The tone holes are tapered or cone shaped or angled holes as measured on my clarinet. Is an undercut tone hole something differant from my description? I visualized an undercut more like a ct'bore or grove of some sort. I thought the tone holes were straight until i took the measurements because I couldnt see the angle by eye. Also, would a slight taper (undercut?) make a differance in the tone or response of the clarinet? I appreciate your comments. Thanks....... ATV
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Author: sfalexi
Date: 2003-05-29 22:28
As I understand from my very limited research on the subject, an undercut tone-hole means that the tone hole is tapered at the point it reaches the bore. Meaning the tone hole has a certain diameter, then tapers outwards to a larger diameter as it reaches the bore of the clarinet. Sort of like a hyperboloid.
This affects the way the air transitions into the tonehole from the bore. I don't know much about the flow of the air but logically and from whatever limited things I learned about air flow in my intro to aeronotical engineering class I assume that the air transition would be smoother, quicker, and would fill up that tone hole faster as the transition is more gradual instead of a sharp 90ยบ turn.
Alexi
US Army Japan Band
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Author: Wes
Date: 2003-05-30 06:41
There are several ways of making the interior end of a tonehole larger than the outer end. Mr. Alvin Swiney has written a lot about that and what he learned from Hans Moennig, probably to be found on the internet.
Undercutting of toneholes generally raises the pitch of the lower register and makes it more free blowing with little change in the upper register. However, some of the larger bore clarinets had little undercutting and still had acceptable 12th ratios between the lower and upper registers. This is a complex subject and it is discussed in Mr. Gibson's little book on the clarinet and some other clarinet texts. Good luck!
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Author: BobD
Date: 2003-05-30 13:12
When drilling a hole in wood the periphery of the entrance and exit locations is generally rather "fuzzy" and the exit location is usually worse than the entrance location. On a clarinet section this fuzziness on the inside diameter(the bore) is detrimental to the sound produced. Undercutting is simply a chamfer on the periphery of the bore end of the hole. I find it interesting that you can measure the diameters of the holes in your horn so accurately and wonder how you do it.
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Author: Avie
Date: 2003-05-30 19:13
BobD, I used my vernier calipers to measure any point on the tapered holes. It works fine w/n .001. I guess I dont have undercut tone holes but something else because its not a chamfer at the hole bottom. Thanks...ATV
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Author: Gordon (NZ)
Date: 2003-05-31 12:28
Is it a specialized vernier caliper, with long slim 'arms', and a 'pip' projecting out at right angles to the reach of each 'arm'? Otherwise, how do you measure near the bottom of the hole without the top of the hole interferring?
Or do you have those expandable "small hole gages" as shown on
http://its.foxvalleytech.com/MachShop1/Inspection/IndirectMeas.htm
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Author: BobD
Date: 2003-05-31 13:10
A Vernier caliper would hardly seem accurate enough. This assumes that he really means a true vernier as opposed to a digital readout dial caliper. I must admit that I'm not familiar with any "caliper" type instrument that would do the job. I suppose even a mini version of inside calipers would be difficult to work with and then transferring the measurement to a "mike".
I guess I'm still thinking that non-optical devices would have enough error built-in to make it a problem.
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Author: Avie
Date: 2003-05-31 13:59
My tone holes taper to smaller at the bore. Maybe it was part of an experiment conducted on the tone holes of the limited edition "super dynaction" BC clarinet of the 60's in an attempt to bring the tone in line with the music the bands were playing at that time. Whatever, I appreciate all your replys. Thanks....ATV
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Author: Avie
Date: 2003-06-03 14:29
I have only heard of one other "Super Dynaction" clarinet mentioned on the BB or otherwise. Although it is exciting to have a rare clarinet it is also difficult to aquire information about it. It would be interesting to know how many were manufactured and there where abouts. Thanks again for your comments. Best regards......ATV
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