WTT - Windway Width

raindog1970 · Post by **raindog1970** » Tue Dec 31, 2002 1:04 am

Just to share a valuable bit of information and save hours of frustration and headaches for those who don't already know this.
The width of the windway seems to be by far the most crucial measurement in fipple design.
I'm not a machinist, so I don't bother with measurements smaller than 1/32"... but 1/32" larger or smaller than the ideal windway width makes a huge difference!
Glenn Schultz once told me the formula to calculate the optimum width of the orifice in relation to the bore diameter, but nobody ever told me the symptoms of a windway that was a bit too wide or too narrow.
I'm here now to let it be known that your whistle will hiss noticably in the 2nd octave, and your notes will be less stable (especially cross-fingered ones) if the windway width isn't optimal.
When I say "hiss", I mean that you will hear a sound like an air leak that can be quite loud in the upper part of the 2nd octave... a most unpleasant thing to say the least.

I'm assuming that the hiss and fragile notes are the result of improper turbulence caused by the less-than-optimal design of the fipple, but that's just my best guess and subject to being completely wrong.
So there it is for everyone to read... and you won't have to deal with the frustration I've gone through trying to figure out why one whistle will play like a dream while another of the same design will sound like crap.

Zubivka · Post by **Zubivka** » Tue Dec 31, 2002 2:43 am

Quite interesting. When you mean width, if I understand correcttly*, it is not its height ? And where do you measure it, since it can taper both ways ?

BTW, what about sharing this formula, please ?

*(sorry, I don't only speak funny...)

chas · Post by **chas** » Tue Dec 31, 2002 7:11 am

I think this is correct for Glenn's particular design, but I have quite a few high-D's of similar bore diameters that have different airway and blade designs. The Abell, especially, is within a couple of thousandths of the same bore as the Weasel, but the airway is quite a bit taller and narrower.

I think much more important is having the airstream properly oriented to the blade.

peeplj · Post by **peeplj** » Tue Dec 31, 2002 7:24 am

Well, if I understand correctly that the width is the measure of the windway / window from side to side, then I have a Cronnolly high D whistle with 2 heads, one with a windway almost a half inch wide, and another with a windway about half that.

Both heads work fine in both octaves, the main difference being in volume. Both are loud; the head with the wider width is louder than a clarinet.

Both heads have a curved windway.

My own thought is that their is an optimimum measure from the blade to the bore, and that the effectiveness of a windway in producing sound will be found by how closely it approaches that distance. Also the height of the window and the sharpness of the blade are crucial for the tradeoff of ease of play in the 2nd octave vs strength of tone and volume in the first. Finally, things like a tapering, narrowing windway and careful chamfering can increase the resistance and pitch stability at a variety of blowing pressures.

But I'm not a maker, and these are only my impressions, not confirmed by experimentation.

Best wishes,

--James
http://www.flutesite.com

serpent · Post by **serpent** » Tue Dec 31, 2002 7:37 am

There are a number of variables affecting play between octaves, squeaks, airy sound, and actual air requirement.

I make two different sorts of whistle head. One has a flat blade and a flat-topped airway. In the other, the blade is curved, and the top of the windway is curved at the same radius, while the bottom is flat.

All other things being equal, the flat/flat combination produces a much louder sound for a given windway width and height, than the curve/curve/flat.

Tendencies to have problems with octaves, squeaks, and airiness are more likely to be related to the angle and sharpness of the blade, from my experiments. As the blade angle increases past about 9 deg off horizontal, airiness and octave difficulties, along with various forms of chiff, seem to show up. As the angle decreases below about 6 deg, the same thing begins to happen, and the volume drops until at about 1 deg, most of the sound is air rush. Means, to me, that there is a rather narrow range of blade angles at which the whistle will operate cleanly.

I have not attempted a curved fipple to match the radius of the blade, yet. That is an experiment yet to come in my Adventures With A Cheap Milling Machine. :roll:

Cheers! Interesting thread!
serpent

chas · Post by **chas** » Tue Dec 31, 2002 9:15 am

Here again, the whistles I own don't bear out the narrow range of blade angles. The Burke is about 45 deg, while the Thin Weasel is maybe 15 or 20 (from the axis of the whistle, I'm not sure what you mean by horizontal, Bill), the Abell somewhat less, and the Grinter and Busman somewhat more. These are all curved windways. Dan Bingamon's have the D-shaped windway, and that blade is maybe 30 deg.

I think it depends largely on details. I suspect that Chris Abell puts the same angle on all his blades, but some of his whistles are breathy and some very pure.

serpent · Post by **serpent** » Tue Dec 31, 2002 9:40 am

That's really interesting and cool! 45 deg? For real? That's one I'd never have gues... Oh. You know what? I'm a dummy! I just looked at the blade on my "practice" Serpent (non-tunable ugly reject that sounds good), and lo and behold! Dummy here forgot about the filing down of the impingement area! My blades are 0.040" thick, and I file back about 0.080" at a much steeper angle than the blade, itself... and lo and behold, it looks (without any way to actually measure it just now) to be at about 30 degrees. And it curves down. And it's rounded on the edge, and filed out underneath the edge, as well.

Well, shut my mouth!

So at the point of impingement on the laminar, I do, indeed, have a much steeper angle!

This is what the WTT threads are all about! Everybody gains knowledge, even if they're thinking they have everything they need! You guys are the _best_! And I always find that I'm not nearly as smart or well-informed as I thought I was! :roll:

Of course, now, I get to spend time mucking around with a file again, tweaking, measuring, tweaking , measuring...
Thanks a lot, dudes.

serpent

raindog1970 · Post by **raindog1970** » Tue Dec 31, 2002 10:12 am

In my design, windway height is regulated by the thickness of the tubing... so it isn't subject to vary due to milling errors on my part.
It stands to reason then, that perhaps the optimal windway width has some relation to the windway height as well as the bore diameter... something I haven't proven or disproven by experimentation.
All I can say for certain, is that 1/32" plus or minus on the windway width of my design causes very undesirable effects.
My experiments with tapering the windway height have produced some very loud whisles, but I haven't tried tapering the windway width.
Blade angle certainly does play an important part in whistle design, but there appears to be a large margin of error in which tone and playability aren't adversely affected by variation.

ErikT · Post by **ErikT** » Tue Dec 31, 2002 1:12 pm

I use the width as one means for controlling the volume. Where X is the width, I've used X/2 to significantly quiet the whistle. Lately, though, I've been using the depth to the same effect; it's a little easier for me to control and simplifies construction (eg. only one windway width).

Erik

Sandy Jasper · Post by **Sandy Jasper** » Tue Dec 31, 2002 1:52 pm

For me, that extra whispy sound is the worst sound of all! Sometimes I just have to turf the mouthpiece and start again.

When I have managed to save it, the problem is usually one of 2 things.

The end of the fipple and one side of the blade are not completely happy with each other. The blade is letting in extra air in a corner. While I can usually adjust such a problem, sometimes the blade is not as wide as I should have made it for that fipple or I locked the fipple in a smidge crooked.

More often though the problem is fixed by simply running a file under the blade and along the sides. Also lightly smoothing off the small sides of the rectange above the blade. In this business, it is what I can't see that often trys to mess with me!!!

Best of luck,

Sandy

Cyfiawnder · Post by **Cyfiawnder** » Tue Dec 31, 2002 2:11 pm

I much agree with serpent, a properly made blade will sound loads better than a sloppily made one. Also imperfections in the blade itself, file gouges and that sort of stuff will cause unwanted turbulance. I sand mine all the way down to 1500 wet grit sandpaper, then I use red jewlers polish to shine it up. Windway height determens airspeed at the blade. If it's too tall the whistle will be very breathy and have HUGE air requirements. If it's too short it will clog realy fast, and be squeaky because it won't properly Direct wind into the blade. I Use a curved blade, curved windway top, and curved windway bottum on my whistles. Wall thickness does play an important roll in my whistles. Since most of the tubing I use has a 1/32" wall then my windways aren't much taller than that. I sand em down a bit, but mostly to smooth them out. So far all of my whistles have a 1/2" long blade, and a 1/4" wide window. They are loud, but not overly so, and are stable through out both octaves. I just finished my First Bass Bb whistle, and it's a monster, but the Blade is still 1/2" and the Windows is 1/4" and it has 2 octave pluss two more notes so Bb,C,D,Eb,F,G,A,Bb,C,D,Eb,F,G,A,Bb,C anything above the tripple octave C doesn't sound. I don't make my blades razor sharp, I round them off a bit at the leading edge. It seams to give the sound a little more stability. With a soft metal like aluminum if the blade is razor sharp then the leading edge is so thin that it will distort as the air hits it, and that will cause some very strange things...

_________________
The gods created whisky to keep the Irish from rulling the world, then gave us TinWhistles to keep us happy.

<font size=-1>[ This Message was edited by: Cyfiawnder on 2003-01-01 17:14 ]</font>

brewerpaul · Post by **brewerpaul** » Wed Jan 01, 2003 5:34 am

Chiming in a bit late here...
My blade angles are approx 20 deg ( OT-- why isn't there a degree sign on a keyboard?). Pretty much the same as the Weasel's
One key factor that Glenn always emphasizes to me is the distance from the fipple to the edge of the blade. Only a very little variation there can make a HUGE difference, especially in high whistles.

brewerpaul · Post by **brewerpaul** » Wed Jan 01, 2003 5:37 am

Oops, I forgot. I agree about keeping the blade nice and smooth to reduce air turbulence. On metal or plastic, this is not a problem once the whistle is finished, but the grain of wood tends to raise as moisture from the breath soaks into it. The hardest woods are not much of a problem, but on the more porous woods, I usually give the finished blade a light coat of cyanoacrylate glue top and bottom to seal it, then touch it up with 600 grit sandpaper. Works like a charm.

Tony · Post by **Tony** » Wed Jan 01, 2003 7:44 am

Paul,
the degree character is made by holding the ALT key down and pressing 0176
20°

chas · Post by **chas** » Wed Jan 01, 2003 8:46 am

Actually, I just took a look at my Burkes, and the high D and C both appear to have blades mor like 20 or 25 deg -- it's really hard to judge not knowing the thickness of the metal. The low whistles appear closer to 45.