Bore size and hole placement?

MrTuffPaws · Post by **MrTuffPaws** » Tue May 14, 2002 2:46 pm

Hello all.

A whistle building question.

I am thinking about trying to build a low whistle, and I have a question that I can't find the answer to in the "Build your own whistle" sites on the net.

I know that hole placement is a factor of length from the lip to the end of the whistle, and I have found numerous ways to find the correct places to drill the holes. But is there any factor on the bore size of the whistle determining where the hole placement is?

Such as, why does a Dixion low D have an easier reach than that of a Howard (I only have the Dixon, but I have heard the above from the reviews and this board)? Is there an equation or rule of thumb that factors in the bore size, or do all low Ds have pretty much the same hole placement?

Thanks
Vilkas

brewerpaul · Post by **brewerpaul** » Wed May 15, 2002 5:32 am

It's fairly complicated..
Bore size, hole placement and hole size all play a part. I'm sure Tom Hastay will sign in on this one, with a LOT more useful information.

MrTuffPaws · Post by **MrTuffPaws** » Wed May 15, 2002 11:55 am

Thanks brewerpaul. I will wait until Tom gives a crack at it. In the meantime, I have some more questions that others can take pass at.

First off, my understanding is that when sounding a note on a whistle you
are setting up an oscillating compression wave in the whistle bore. When
releasing your finger from one of the holes, you are, in affect, shorting
the pipe, and causing the compression wave to jump to a higher frequency.

Now, why are the finger holes of different size. Being that they are used
to shorten the pipe, theoretically, they could be of any size and have the
same effect. Now I am also aware that in real life, things don't act
exactly as they do in the equations. So why the different hole size? What
goes on with the compression wave that requires different hole sizes for
different frequencies? Why are they round (Other than drill bits being
round)? Would not square holes allow for more accurate placement?

Also, how does bore size affect the finger hole placement? I have heard the following rule of thumb:
"-Smaller whistle diameter than normal: -Move finger-holes upwards towards
the fipple."
but I don't really want to go through 30 meters of pipe to find out rules by
my self.
Is there any equation that could help me get an idea of hole placement in
relation to pipe length and bore diameter? Somebody out there has had to
have worked this out.

ChrisA · Post by **ChrisA** » Wed May 15, 2002 12:42 pm

On 2002-05-15 13:55, MrTuffPaws wrote:
So why the different hole size?

Because a finger-hole is neither the same orientation nor the same size as the end hole that generates the bell note... the narrower the hole, the flatter the tone, the wider, the sharper, until you are open enough to generate the note for that length.

Different holes are different sizes mostly to control hole placement, so that you have:
o..o..o....o..o..o instead of
o....o.o...o.o...o (or whatever, that's not the real placement.

The Boehm system flute was originally designed for all holes to be the same size, and as large as possible, and placed in the 'acoustically correct' positions... which necessitated all the keys.

Why are they round (Other than drill bits being round)? Would not square holes allow for more accurate placement?

Because circles cause the least turbulance, and thus the least 'air' in your tone. Corners would create lots of wasted air, etc. (Which has not stopped me from considering making a square-bore square-hole whistle, just to see what it actually sounds like... probably awful, but it'd be a fun experiment.

)

Also, how does bore size affect the finger hole placement? I have heard the following rule of thumb:
"-Smaller whistle diameter than normal: -Move finger-holes upwards towards
the fipple."
but I don't really want to go through 30 meters of pipe to find out rules by
my self.
Is there any equation that could help me get an idea of hole placement in
relation to pipe length and bore diameter? Somebody out there has had to
have worked this out.

Yes... Benade's book on the physics of music is recommended, but I haven't read it...

I think, though, that you'll only need to 'waste' 1 foot of pipe... leave long ends on it, drill holes in it, and alternately cut your ends until you get 'close' to a D whistle, and then file ends until you get exactly a D bell note and some reasonable approximation of other notes... see how much they can be fixed by changing hole diameter (start with small toneholes!); if all of your holes remain tiny, move up, and if they're all huge, move down. Remember that increasing diameter moves the uppermost-edge of the tone-hole as well as remove restriction from the air flow.

You also might look at mimf.com (music instrument makers forum); they're infinitely more commercial than here, and heavily focused on guitars, -but-, they do have a wind-instruments section and archives of some 'important' discussions (if you register - free registration) including some on tone hole placement issues.

Chris

EditPS: Oh... -low- whistle... err, okay, you'll have to waste 2 feet of pipe then...

PPS: When figuring out hole size, remember half holing... effectively reducing hole size flattens a tone, f.g. c#->c nat. half hole. This helps keep the direction straight. And should give you more confidence that you can fix up your first whistle to be in pretty good tune with diameter adjustments...

[ This Message was edited by: ChrisA on 2002-05-15 14:43 ]

[ This Message was edited by: ChrisA on 2002-05-15 14:49 ]

AngeloMeola · Post by **AngeloMeola** » Wed May 15, 2002 9:47 pm

Check out the flutomat calculator.

http://www.cwo.com/~ph_kosel/flutomat.html

You can make either 6 hole or 8 hole whistles. I've made one of each and actually like the 8 hole design better. You only use the top 6 holes for fingering. It seems to strengthen the bottom notes by moving them up the tube.

brewerpaul · Post by **brewerpaul** » Thu May 16, 2002 5:37 am

That reminds me: regarding the flutomat calculator-- what do you use as the "diameter" of the embouchure hole. On a whistle, this hole is actually the rectangular "window". What is the diameter of a rectangle?

ErikT · Post by **ErikT** » Thu May 16, 2002 6:24 am

Seeing as Thomas must be on vacation and the bore diameter question hasn't been answered yet I'll just outline it here.

As the bore diameter increases the fundamental tone length decreases (in general); this is the distance from the leading edge of the window to the end of the whistle. So you will typically find that those whistles with larger bores will also have correspondingly easier reach between notes. Of course hole size plays a major role and their are many aspects coming together at once such that it is difficult to isolate the effects of each. I think that Heizenberg was an instrument maker.

So why not just have big diameters so that everyone can reach? Well there are two aspects fighting against each other... optimum bore to length ratio and finger reach. Depending who you talk to the ideal bore to length ratio is 1:21, or 1:23 but opinions vary. This isn't always the ideal ratio for hole placement and you can come up with some pretty far apart fingerings.

Did I make sense... I often wonder ?

Erik

edited either because I called everyone names and then thought better of it or because I couldn't spell 'diameter'. You be the judge.

[ This Message was edited by: ErikT on 2002-05-16 08:25 ]

AngeloMeola · Post by **AngeloMeola** » Thu May 16, 2002 3:29 pm

On 2002-05-16 07:37, brewerpaul wrote:
That reminds me: regarding the flutomat calculator-- what do you use as the "diameter" of the embouchure hole. On a whistle, this hole is actually the rectangular "window". What is the diameter of a rectangle?

I use the diameter of a circle with the same area as the window. It doesn't seem to change the hole placement much. The change from just leaving it at 0.5 is less than I file off to tune the note.

DanD · Post by **DanD** » Fri May 17, 2002 10:01 am

On 2002-05-15 14:42, ChrisA wrote:
Why are they round (Other than drill bits being round)? Would not square holes allow for more accurate placement?
Because circles cause the least turbulance, and thus the least 'air' in your tone. Corners would create lots of wasted air, etc. (Which has not stopped me from considering making a square-bore square-hole whistle, just to see what it actually sounds like... probably awful, but it'd be a fun experiment. )

Check out http://www.lopatinflutes.com/square.html

Thomas-Hastay · Post by **Thomas-Hastay** » Sat May 18, 2002 1:30 pm

I'm impressed with many of you! I think you realy listen to the technobabble of us amateur whistlesmiths(he he).

First: Vilkas,
The bore's inner diameter is a limited variable based on the full wavelength of the Key frequency. An average bore diameter for a concert flute is 1/32. whistles can have a variable borelength between 25 and 40 times the bore's diameter.

As the borelength on a D whistle gets shorter, the pitch becomes higher and the bore diameter must become larger to counter-act and lower the pitch again to D. The reverse is also true.

When the bore becomes too large in diameter,it loses its acoustic capacitance or its ability to compress and decompress the internal aircolumn and becomes weak and whispery. Making the toneholes smaller helps to retain some compression within the bore,but this also groups the toneholes closer together.

If you will be patient, I will work out some simplified equations on making a "basic" whistle with expalinations on the relationships between bore,frequency and tonehole size/position and post them in this topic line. I hope the other whistlesmiths will chime in with their views and equations.

Be back soon! T. Hastay.

amar · Post by **amar** » Sun May 19, 2002 11:40 am

tuffpaws, i found this website, hope you'll find the info you need:
http://ourworld.compuserve.com/homepage ... periem.htm
cheers, amar