Whistle Tech Talk (edited to add this line)
Though fingerhole placement, per se, can be easily calculated for a whistle, the diameters seem to vary quite a lot within any one key. I’ve had the opportunity recently to examine about 20 low- and high-end whistles of various manufacture, and note a fairly wide variation in hole diameters. At one extreme, my new (gorgeous, pretty, lovable, sweet, I love it!!! ) Elfsong has a #5 that is not only markedly smaller than any of the others on the instrument, but also from those on any other make I’ve seen. OTOH, the Irish (no brand name) D I use to rough-tune, has a #5 that is larger than the others.
Now, I know from making, that one way to shift pitch sharp is to drill a larger hole on the same, or fipple-end-shifted center. That said, I also know that, once you’ve got the placement and diameter calculated for a batch of tubing stock, you don’t usually have to vary much to tweek into perfect tune.
Hole diameter is also responsible for volume, to some extent.
With all that in mind, what speculations have we for the rather wide variability from brand to brand, and, more to the point, from whistle to whistle within a brand?
Cheers!
Bill Whedon
“Ta an sneachta go frasach fa bheal na n-aitheann’”
-“An Maighdean Mhara”-
[ This Message was edited by: serpent on 2002-11-05 10:42 ]
Good stuff, James! I remember that you posted those rules-of-thumb in a different venue, but they’re really appropriate here. I’ll get on the woodenflute list today!
I, in particular, am working with metal that’s not a whole lot thinner than some wood instrument shells, so the bit about undercutting could well apply to some extent. Paul, if you’re “listening”, about how thick are your bodies in the fingerhole area? Any other wooden whistlesmiths around? And if anyone else has worked with heavier gauges of metal, 0.035" (0.89mm) and up, what’s been your experience with undercuts?
As a point of reference, on a straight-tube C steel whistle my 1, 3, and 4 holes are the smallest, usually, being in the ballpark of 1/4" diameter. 2 is about 9/32", and 5 and 6 are around 5/16" Those dimensions will vary with tuning tweeks by a few 64ths. I haven’t intentionally tried any undercuts.
Hole placement for me is not so technical as perhaps it is for others. When developing a new key, I take an existing formula or whistle, drill the first finger tube that way, tune it up then start my changes. If a hole seems too small, I move it down, if it is too big, I move it up. Once I have them where I would like visually and so that it feels good, I play it. This step tells me a lot. If a hole needs to be moved, I can tell by the sound I get. A squeak, thin sound, note with a harmonic undertone or a note that flips to the next octave too easily indicates to me that the holes need to be moved. A subtle movement up or down can do a lot for the playability of an instrument. For me charts and formulas are discarded the minute I drill my first holes. After that I just use my instinct and common sense. Once I have the hole placement figured out and I am really happy with the result, I mark it off on a template and use that as my master.
I have a general idea how big each hole will end up and pre-drill them to just under that size. I use a rackmount tuner to fine tune each whistle. There is always a slight difference in final tuning as by using a template to mark the holes they can vary slightly in placement. The higher the hole, the smaller the hole, the lower the hole the bigger.
Why is the 4th hole from the top so small? Each whistle has it’s own placement but if it is almost a given that this hole is the smallest. This is because it is only a semi-tone lower than the next hole up as apposted to the whole tone steps in most other holes: Example D-E (Tone) E-F# (Tone) F#-G (Semi-Tone) G-A (Tone) A-B (Tone) B-C# (Tone) C#-D (Semi-Tone). Usually the first and 4th holes are the smallest and that is because they only take half note steps to the next note. How low or high the holes are on the finger tube ultimatly determine the size and each builder has their unique placements and reasons for them!
Enough theory for this elf this early in the morning,
Undercuting and outside radiusing improves laminar flow which increases the chimney effect on thicker walled whistles.My Kerry LP F and Susato low D were both noticeably louder after I performed this tweak.Both these whistles have great intonation in both octaves I might add. Mike
0.078" thickness. A hair shy of 5/64". So, do you undercut &/or radius? I’m sure there’s a definite “chimney effect” there, 'cause there is on the new brass, and it’s only 0.040". I’m just about to begin test-drilling the D tubes in earnest - already made a couple brass protos that are pretty decent. I’ll keep y’all posted on what I discover!
Cheers,
Bill Whedon
On 2002-11-05 11:11, mike.r wrote:
Undercuting and outside radiusing improves laminar flow which increases the chimney effect on thicker walled whistles.My Kerry LP F and Susato low D were both noticeably louder after I performed this tweak.Both these whistles have great intonation in both octaves I might add. Mike
“laminar flow”!!! Yer scarin’ me Mike! I thought the laminar broke up pretty much due to turbulence at the blade. Oh… Dumb me. I overlooked the Coanda Effect! Never mind… This is still scary! It’s starting to come together and make… (oh, NO!) SENSE!! (shudder!)
Cheers,
Bill Whedon
On 2002-11-05 11:11, mike.r wrote:
Undercuting and outside radiusing improves laminar flow which increases the chimney effect on thicker walled whistles.My Kerry LP F and Susato low D were both noticeably louder after I performed this tweak.Both these whistles have great intonation in both octaves I might add. Mike
“laminar flow”!!! Yer scarin’ me Mike! I thought the laminar broke up pretty much due to turbulence at the blade. Oh… Dumb me. I overlooked the Coanda Effect! Never mind… > > This is still scary! It’s starting to come together and make… (oh, NO!) SENSE!! (shudder!) >
Cheers,
Bill Whedon
Coanda effect!!?This sounds even scarrier.One of my old posts titled "to chamfer or not to chamfer"contains a lot of great tech info from Neil Dicky on laminar air flow and whistle tone holes…definately worth checking out. Mike
Excellent stuff, Mike! Thanks! Fortunately, I’ve enough material thickness to be able to chamfer both edges - soon as I get back to the shop, I’m going to do a couple and see what happens. I have some inverted-cone diamond grinders for my handpiece, and they’re small enough to fit through the fingerholes and do the inside of 'em very smoothly! Paul, other wood whistlesmiths, you may be able to use them on the wood items, too. They’re in the set of “50 pc. diamond mounted point set” ($27.99) from Harbor Freight. http://www.harborfreight.com search on “diamond”. Just a caveat - I tried the 20-piece set they have for $5.99 – don’t. Soft shanks, not much by way of diamond, bad sinter.
Cheers!
Bill Whedon
Bill, I think the flow here is the air flow in and out of the tone hole. In this case, the flow is so small it probably is laminar, although I haven’t done the Reynolds number calcs to prove this.
I think that a positive curve ground into the inside edge of the tone hole would certainly promote a laminar flow due to Coanda Effect being more pronounced over curved surfaces than angles, so you’re most likely right. Airflow diagrams of subsonic aircraft wings definitely do exhibit laminar flow, and the wings are themselves prototypical of Coanda Effect devices.
Not wanting to be mysterious, and certainly not wanting to seem too pseudoscientific, here’s a practical explanation of what happens: When a positively-curved surface passes through an airflow (or an airflow passes over that surface), the velocity of the air is increased when it reaches the curve, and a partial vacuum is formed there. That’s how “lift” works in a wing. Once it’s passed the point of incidence, it slows down again, and picks up some turbulence. In a whistle tone-hole, some of the laminar air would still tend to track around the curve, and exit from the hole, still as a laminar flow. That’s oversimplified, but it gives the gist of it without complex math!
Remember, I’m not a physicist, and I don’t play one on TV. If any of you would like to post the numbers and formulae for your scientific brethren, please do! I learn more every day, and every little confusion helps, 'cause I don’t like being confused and I study any sources of same!
There is bidirection flow in open tone holes, air is moving in out and in - but there is a certain small amount of positive flow. So you can consider some of the air moving through the hole.
The edge chamfering, rounding, etc. has a much greater effect in high pressure instruments, bagpipes, clarinets, etc.
The chamfer does cause the stream to hang closer to the surface, this in turn makes the tonehole less sensitive to pressure changes in each octave. If you have a sharp edged tonehole and fluid properties of air spill over the edge it causes the air to move away from the surface just like an arc of water is created when you pour it from a glass.
When the octave changes, the pressure changes, this allows for a wide change in that air cushion along the surface.
If you can increase the efficiency of a hole to use more of it’s area, you will not get as much variance between octaves.
I work at place were they measure Effective area, the area used by air through holes in jet engine parts http://www.ccdi1.com. The effective area is always small than the geometric area of a hole. The efficiency is the ratio of effective area / geometric area.
Aircraft engineers uses ASME nozzles to calibrate area measurements, it is a hole with a specially radiused entry that makes it 98.7% efficient.
On flutes, you’ll find that the old school performed chamfering and undercutting of toneholes. The age of plastics came and people forgot the old art. Today, many are rediscovering this and now they know why it works so well.
Daniel, do you have any measurements of the actual ratios of effective to measured diameter for various hole geometries? In my current hole calculation model I used 0.75, but I have no idea if this is reasonable.
Jesus Christ, I risked reading one of these WTT posts. NEVER again! You guys talk scarier shite (i wrote shite, and not shit, so there..) than I do, and I’m doc..they say…
As long as them whistles sound good..
Yes, it’s around 70 to 80% depending on the smoothness of the inlet. The estimated number is the value plugged into the chimney correction formula. I don’t mess these as much since metal whistles don’t have much chimney.
I have local cutoff frequency / frequency ratios in my toneholes spreadsheets.
hi all ye techno guys e.o. i still have probelms to play a high C whistle(i play the burke low D pro fluent). don’t ask me why, but playing a high D gives me much more comfort than a high C. so i’m looking for a high C non metal kinda whistle where the space between the mouthpiece and the upper fingerhole is very short, or similar to a high D. also the the holes should be closer together then a normal C. an alba high C would be the answer but stace won’t make any other high C’s then alli’s. if any make comes in your minds, please let me know
Check again with Alba: she does also high whistles of Tufnol, which is a composite (fiber-chaged resin) akin to Burke’s ebonite, with a feel and sound close to wood. The line is called “Highlander whistles”.
Also, any whistle with a conical bore will bring the left hand up–just see a Clarke, Shaw, or Copeland. The top hole on a C gets almost as close to the fipple than with a D in straight bore.
I regret I don’t know exactly who does conical bore wood whistles. There are Bleazey and Swayne in England for sure.
There’s also Yvon Le Coant in Brittany but he doesn’t make C’s yet; same for Fred Rose, and I’m not sure his whistles are cone or straight-bored.
In the US, you’d have at least Sweetheart who makes his “standard” wood whistles both in D and C, at a quite reasonable price.
thanks for your helping hand zubivka, burke composite and stacey’s highlanders are the only ones who will tickle my fancy in sound. the burke is to long and stacey don’t make any C highlanders, i’ll just hang in there till she does.i think they’re worth waiting for
) Elfsong has a #5 that is not only markedly smaller than any of the others on the instrument, but also from those on any other make I’ve seen. OTOH, the Irish (no brand name) D I use to rough-tune, has a #5 that is larger than the others.
One of my old posts titled "to chamfer or not to chamfer"contains a lot of great tech info from Neil Dicky on laminar air flow and whistle tone holes…definately worth checking out. Mike