Another strangled flute

[Casey Burns]

I still think "strangled" as a synonym for thread-wrapped is a loaded term. Maybe we can stick to the technically more correct and less loaded term "bore compressed".

Even with rings I have seen the corking of my flutes result in a crack. My ODs are determined by what wood diameters I can get - usually narrower than what I would like to get. I size the tenons and sockets for an appropriate amount of thread, not too much and not too little. If this is sized inappropriately for someone corking it later on, that is their problem - not mine. But it becomes my problem when I am asked to replace a head joint that someone else cracked by applying cork to it, and made it too tight for the socket.

I still do not see any convincing data that thread wrapping causes the bore compression. I found no evidence that this happened on a boxwood flute that has been in my workshop wrapped and kept together for 7 years. At this point this is just a theory that remains to be tested.

Casey

[Terry McGee]

I still think "strangled" as a synonym for thread-wrapped is a loaded term. Maybe we can stick to the technically more correct and less loaded term "bore compressed".

I've never proposed strangled as a synonym for thread wrapped, but for something that has caused collapse of the bore. I'm looking for an expression for when we go beyond minor bore compression - when the degree of bore compression is so great that it starts to interfere with the normal operation of the flute. Tracheomalacia. Subglottic stenosis. Croup. Strangulation works for me, but feel free to suggest a better name. Bore collapse, perhaps?

I still do not see any convincing data that thread wrapping causes the bore compression. I found no evidence that this happened on a boxwood flute that has been in my workshop wrapped and kept together for 7 years. At this point this is just a theory that remains to be tested.

It also seems to be our only theory, other than Aliens strangled my flute!, so I'm happy to run with it until someone comes up with a better one.

The more I think about it, the more I think moisture cycling is an essential part of the mechanism. A wet flute will have a softened swollen tenon, trying to burst through the encircling band. Possibly, a soft, flexible wrap will enable some wiggle-room; certainly, a tight, hard wrap will offer less.

It might also explain the mechanism in the mysterious "locked thread wrap" phenomenon we come across from time-to-time. This is where an old flute turns up with a joint or joints that are infuriatingly loose, yet can't be separated, because the thread wrap has for some reason detached itself from the bottom of the thread channel, and attached itself to the inside of the socket. Tenon gets wet, expands and forces thread into tight contact with the socket. Breath condensate glues it there. Tenon then dries out, shrinking away from thread pack. Thread pack remains firmly attached to inside of socket, but imprisoned by the tenon tip shoulder. Loose but inseparable, grrrr! It would be interesting to see if such cases also show signs of bore collapse, or at least significant bore compression.

Terry

[Casey Burns]

Just to be thorough though, we need to rule out that this doesn't happen to corked flutes as well. Just because it might happen to thread wrapped flutes doesn't mean that it can't happen with cork. I'll perhaps do that test I described previously using both.

Casey

[I.D.10-t]

I don't know, the wrappings on a tenon remind me of the Strangle knot although the whipped tenon would be more accurate.

[Terry McGee]

Just to be thorough though, we need to rule out that this doesn't happen to corked flutes as well. Just because it might happen to thread wrapped flutes doesn't mean that it can't happen with cork. I'll perhaps do that test I described previously using both.

Casey

Indeed, why not.

It might be useful to do an "in extremis" test first, to probe the theory and make sure we're not wasting our time. Turn a really thin tenon, with cylindrical bore as discussed. Turn and comb it neatly, so we can see the nature of any distortion that occurs. A photo would be good for later comparison. Measure and record ID and OD. Wrap it as tightly as you can with hard thread, and subject it to the "wet inside for an hour a day" treatment. If we can't make that curl up and die, or at least exhibit measurable compression, we'd have to rethink. If we can make it curl up and die, then it's worth proceeding with the more detailed comparative tests. They may take a lot longer to bear fruit.

And it will be fascinating to see if the combing changes to resemble those on the flute I have here.

Terry

[Casey Burns]

I'll let someone else do the experiment at this point. To me it is a non-issue as far as my flutes are concerned.

All the Baroque flutes were thread wrapped. And the best modern Baroque flute makers such as Rod Cameron use thread wrappings, not cork. Not historically accurate for one thing. Also, early bagpipes, early clarinets, etc. Why change something that works fine?

I think pursuing the color of the outside of the flute as how it affects tone is well worth investigating. Boxwood is light yellow. But old boxwood is deep orange. How does this affect the tone? It seems that older boxwood flutes play better than newer ones - is this due to the color? Or am I color blind?

Casey

[talasiga]

Just to be thorough though, we need to rule out that this doesn't happen to corked flutes as well. Just because it might happen to thread wrapped flutes doesn't mean that it can't happen with cork. I'll perhaps do that test I described previously using both.

the third leg of thoroughness and perhaps the primary leg is to investigate whether the moisture logged wood is the core factor because the more we think about it the more we might begin to

..... think moisture cycling is an essential part of the mechanism. A wet flute will have a softened swollen tenon, trying to burst through the encircling band. .......

My point is moisture gets in most effectively WITH the grain rather than through the wall of the tube. With tenons resting in sockets we increase the chance of that.

[Terry McGee]

I'll let someone else do the experiment at this point. To me it is a non-issue as far as my flutes are concerned.

Casey

I can understand that feeling - it's even less relevant to my flutes, but we've come this far ...

So I've embarked on the "in extremis" test. It's a 30mm long piece of boxwood, bored to 18mm (chosen as it's typical diameter around the middle of the top tenon). I then cheerfully turned down the outside to 20mm, ie 1mm wall thickness, which didn't leave much room for a thread trough! I had intended 22 mm, with a 20mm trench. Sigh - should have waited for the first coffee of the day - so it's a little more "in extremis" than I had in mind. So I made the trough as shallow as seemed reasonable (19.6mm OD) and cut very fine combing. I worried about it holding together long enough to get wrapping on it, but it's been perfectly behaved.

I used some thread I had lying around the workshop, and put it on pretty tight. I started with the woodlathe on slow, but it's still rather fast for wrapping (should have used the metal lathe!), so it's more jumble-wrapped than I intended. Oh well, that's what preliminary tests are all about. I finished up wrapping by hand, and it's clear I'm not a professional flute wrapper! I left the end of the thread free, rather than imprisoning it, though I don't think that will make much difference. I stopped at 0.5mm depth of thread (OD of thread pack now average 20.6mm), which is less than was on the strangled flute, but should be enough to show some results.

I've taken some initial measurements and will track them over the days ahead, while I try to think of mean things to do to it - the sort of mean things we do daily to our flutes. I measured the length carefully, to test Neville Fletcher's observation that any crushing a cylinder will also shorten it.

The bore at the middle of the wrap immediately came down to 17.75mm, but I think that is to be expected. Wood is elastic, and as we saw from the maths, this very thin wood cylinder is now under a lot of force. Left alone, they will reach equilibrium, where the crushing force of the cotton equals the restorative force of the wood. But of course, wood is never left alone - it absorbs and releases moisture and swells and shrinks with the daily humidity cycle. And once it has appeared to have settled down, I'll start hitting it with a daily hour's practice simulation. I suspect that's when the fun will start.

I'll get back to you when there's something to report.

Terry

[Rob Sharer]

I'll let someone else do the experiment at this point. To me it is a non-issue as far as my flutes are concerned.

Fair enough, though what's right for your flutes won't necessarily be right for others.

I have in front of me a Burns flute section. The tenons are massive, way more substantial than the tenons on any other flute I have in my possession. I think it's fair to say, Casey, that you've chosen a fairly unconventional design here, for better or worse. Those of us with more traditionally-constructed flutes may need to follow a different set of guidelines.


Rob

[Casey Burns]

Rob, I would think that my design is for the better. Last thing I want now besides people worrying that their flutes are being strangled is now them worrying that their tenons are too thick, or simply too unconventional. These aren't unconventional to me. In fact, I am quite used to them now after 30 years of doing this.

I've seen a bunch of old 19th century flutes with too thin tenons that are all cracked and glued back together. The corked ones are worse in this regard, probably from the lack of support provided by the thread wrappings. It appears important to leave a healthy thickness - Terry, maybe there is a direct relation between how much wood is left on the tenon and its propensity for this bore shrinkage. Your experimental tenon described above I would suspect more likely to compress, than my fairly robust thicker walled and apparently unconventional to some tenons.

When turning the tenons, the flute joints are held to the lathe by opposing conical centers, held with enough pressure that the flute part stays turning when a tool is applied to it. Make the tenons too thin, and these will split at this point of manufacture. I also use cones to hold the flute part when drilling the tone holes or milling slots for key bases, which applies a force at 90 degrees to the axis of the flute body. At this point the tenons are further reinforced against this cracking in manufacture by the thread. I gauge mine to have a wall thickness of 1.75mm or greater. I usually leave a swelling on the socket, which leaves more effective wall thickness, than what was traditional on say a Rudall and Rose. This is especially important on flutes that do not have any metal rings for support on the socket.

Per another thread - maybe its the color of the tenons that really matters.

casey

[Rob Sharer]

Rob, I would think that my design is for the better. Last thing I want now besides people worrying that their flutes are being strangled is now them worrying that their tenons are too thick, or simply too unconventional. These aren't unconventional to me. In fact, I am quite used to them now after 30 years of doing this.

Be that as it may, we all have to deal with the flutes we have. For those of us not fortunate enough to own a Burns, we need to be aware that the tenons may indeed be a bit more susceptible to mistreatment than your more robust offerings.



Rob

[Casey Burns]

Mine suffer some too. Its amazing how many people set their flute down on a chair or a couch, only to have someone sit on it and break the tenons or sockets or both. Or these get set on a music stand (who brings a music stand to a session?) and they get launched off of that. Sometimes its just fumble fingers dropping it onto a hard floor while disassembling. I have one such repair in the shop right now. A few have been oiled, then left in the easy range of Spot or Fido, the house Rottweiler. I have a few dog-chewed examples that have been returned to me, which I am about to add to a page describing my 30 years of flute making experiences (coming later this summer). Someone tried repairing their flute with an axe (see below). One got eaten by a horse.

If I sound grumpy, its because I spent the afternoon working on my State of Washington Business and Occupation Taxes which are arcanely devised. Did this instead of working on 4 flutes - but they all needed another day in a warm space before I add the metal.
See http://dor.wa.gov/docs/pubs/excisetax/b ... x/bofs.pdf if you really want to torture yourself.
They are revising these taxes next year to account for flute tenon shrinkage - the greater the shrinkage the higher the tax burden - thus I am thinking of making my tenons thicker, say 10mm or 20mm or more wall thickness. We'll see if these tenons will shrink any!

Casey

Flute repairer (anonymous) hard at work (note the middle joint on the ground). This flute suffered from strangled tenons.

[Rob Sharer]

Aaaagh!!! DON'T DO IT!!!!


I bet it would feel good to really smash one, after being so careful around them all of the time. Somewhere, I have an excellent picture of myself burning a guitar in the fireplace. Little Bitseach was asking for it, too.


The worst flute execution I'm aware of was the one resting on the recycled, swaybacked church pew in the pub, on which several people were sitting. During the tunes, the peur aul' flute slipped between the seat and the back. At the end of things, all rose in a body to bid farewell.....CRUNCH!

Ar dheis Dé go raibh a anam.



Rob

[George]

Fair enough, though what's right for your flutes won't necessarily be right for others.

I have in front of me a Burns flute section. The tenons are massive, way more substantial than the tenons on any other flute I have in my possession. I think it's fair to say, Casey, that you've chosen a fairly unconventional design here, for better or worse. Those of us with more traditionally-constructed flutes may need to follow a different set of guidelines.

You're a funny guy Rob ...

What would those guidelines be?

Your guidelines for wrapping tenons was something like "don't feck it up" if that's all it is then I don't think people have to worry =)

Going back a bit - Benhall.1 caught the error Terry made in adding up the force first. In any case does having the force being applied to the tenon wrong in your head by well over a couple thousand pounds affect your opinion on thread wrapping at all? Serious question, not trying to poke fun.

[Terry McGee]

Going back a bit - Benhall.1 caught the error Terry made in adding up the force first. In any case does having the force being applied to the tenon wrong in your head by well over a couple thousand pounds affect your opinion on thread wrapping at all?

Whoops, sorry George, I seem to have missed that bit. Can you direct me to where you caught my error? Or, run me through it again?

Terry