Another strangled flute

[George]

This whole discussion reminds me of teaching pulleys and vector forces to students, in the end the only way to get most people to understand (and note I did not say all) was to provide hands on demonstrations - such as the one where I had a couple of the smaller students pull a pickup truck with its hand brake on across a dry paved parking lot, just using a rope (a big rope) and a tree.

If my "hands on experience" confirmed what you're saying I wouldn't be doubting your numbers.

Why don't you take your own advice and thread wrap your finger, you can find less than 5min and it won't hurt ... maybe you, Terry & Rob won't be convinced until you feel it for yourself.

Even a solid well commented math proof will probably not convince some since it seems that many do not see that each turn of a continuous thread applies a force that adds up with each turn.

Unfortunately I do not have time to come up a demo and video at present, perhaps by the time Terry's experiment is done - till then over and out for me

It's the *tension* applying the force not the thread, the number of wraps in one layer are irrelevant if the tension is the same.

The tension is the force and length of the layer is it's footprint. Stand on your tippy toes and roll down onto your feet, surface area increases but it's still the same force. Get someone on your back and the force doubles.

[George]

My logic in proposing this test was based on George's resistance to the idea that more turns increases the force applied to the tenon. Since that force is limited by the breaking strain of the thread, it seemed likely to me that showing the breaking strain of a mass of threads is far higher than one thread, we could extrapolate that to the force exerted by a mass of threads is far higher than one thread.

You've been arguing with yourself on this one, I don't doubt the breaking strain of a mass of threads is way more than any individual strings breaking point. Isn't that how rope works?

But you're conflating the ability to withstand more force with saying *it is* applying more force, two entirely different things.

[George]

This one little observation neatly sums up my own unceasing wonder at certain responses to this topic. None so blind...

I would say many, if not the majority of your posts in this thread have been condescending little comments about your disbelief of others, puns and movie quotes. I personally don't find it helpful nor do I enjoy being talked down to. Just so you know, "mate" =)

[Terry McGee]

As I said further up, I don't think we're going to get any agreement on the numerical question of what forces are or might be at work. I have asked Neville Fletcher for some clarification on the maths, but haven't heard back yet. In the meantime, let's all calm down and remember we are on the same side.

Those pesky children are now pleading for some bread and dripping, so I'd better go make another flute ...

Terry

[NicoMoreno]

I personally don't find it helpful nor do I enjoy being talked down to

I agree. Please, Rob, just stop posting to this thread. It's just annoying.

[Rob Sharer]

I personally don't find it helpful nor do I enjoy being talked down to

I agree. Please, Rob, just stop posting to this thread. It's just annoying.

Hey, I'm genuinely interested in the topic. I'm not that interested, however, in the pseudo-scientific gobbledygook that infests this thread.

I'm especially not interested in being told what to do. I'm staying...

[Arch_Angel]

Well, I wrapped my finger. Here are the results.

That area of my finger had a circumference of 2.25" after being compressed by the thread (the strongest I had in stock for quilting). The wrap was 15 threads wide and I was finishing the 2nd wrap when, SNAP!!! Because I was able to finish the experiment, I calculated the Pressure based on Terry's formula. Well that should be about 46lbs of force. Yet, my finger is still here, the muscle seems to be fine. The skin didn't even break. (I was more worried about the friction cutting through. I'm typing with the finger as I write this. I guess I'll try some of my spider wire (90lb test) next.

Sorry Terry I really think you've jumped the gun on putting this on a dedicated website. You having done any analysis to confirm that the use of cork doesn't produce any similar effect with it's exposure to dry and humid conditions. None of it even attributes the effects to or sole toward the thread as the culprit.

Rob, I don't mind you watching, but if all your input is going to be is satirical then please leave it behind.

Rob, I think your going to have to paint Terry a picture (literally) on why the force is distributed throughout the tenon.

I forgot who mentioned friction as having not be brought up. I did. Ok, I was more focused on the friction warping the wood as the wood dried but I did bring it up.

[Rob Sharer]

Rob, I don't mind you watching, but if all your input is going to be is satirical then please leave it behind.

Let's see, how can I put this gently....

Don't presume to tell me what to do.

And if you think I haven't made some serious contributions to this thread, clean your damn glasses.



Rob

[Arch_Angel]

Rob, I don't mind you watching, but if all your input is going to be is satirical then please leave it behind.

Let's see, how can I put this gently....
Don't presume to tell me what to do.
And if you think I haven't made some serious contributions to this thread, clean your damn glasses.
Rob

Sorry, I had to compress your quote down. I haven't told you what to do. I politely asked you to not post the satirical remarks. I have no say in what you post. Now if a moderator thinks you have gone to far, that's a whole different story.

After CAREFUL review of the 22 pages of this thread. I have found 3 post from you which barely stretch toward "serious contributions". The closest I could come up with were pages 1,4, and 13. I almost gave you credit for 1 more, but I forget what page it was on. In contrast (and with out actually counting) you have averaged about if not more than 1 time per page. This leaves you with a 1 in 7 ratio of useful information.

Back to the issue.

George correctly posted
"So the force applied to the tenon = tension/radius

Tension = 700g
Radius = 1cm
700/1 = 700

Why are you combining the string's force from both radii lengths ... isn't it an even 700g all around the tube?

So then 700g*13=9,100g
9,100g = 20lbs"

I add to that...
9.42 cm^2=1.46 sq.in.
20lbs/1.46sq.in.=13.698 Psi, .944 bar, .13698 N/cm^2, 1369.8 pascal.

[Terry McGee]

Sorry Terry I really think you've jumped the gun on putting this on a dedicated website. You having done any analysis to confirm that the use of cork doesn't produce any similar effect with it's exposure to dry and humid conditions. None of it even attributes the effects to or sole toward the thread as the culprit.

I don't see any point in investigating cork as we have no evidence of cork squashing flutes. Nor can I see a mechanism by which it could happen. I'm surrounded by evidence of thread squashing flutes - most of the old flutes in this room show measurable distortion, with the two instanced in the article simply the worst cases I've seen. Nobody has come up with any other suggestion as to how these flutes became squashed, and the test tenon which consisted entirely of a tenon and a thread wrap was similarly squashed. I'd call that Q.E.D.

I think more valuable than denial would be attempting to work out what precautions one could take to make sure it didn't effect your flute, sooner or later. For example, could we wrap a buffer layer around the tenon, and then wrap thread over that? What buffer materials can we think of? A thin layer of cork would be an option, but maybe a thin layer won't offer enough wiggle room? We saw 0.8mm increase in diameter at the ends of the test tenon, but maybe we don't need that much buffer. Although then, we'd have to allow that the thread it going to cut into and compress the cork, as anyone whose tried temporarily augmenting thin cork with thread will attest.

An interesting conundrum. Green hat time, people. (I meant the de Bono green hats of creativity, not leprechaun flute-player green hats!)

Terry

[Rob Sharer]

Sorry, I had to compress your quote down. I haven't told you what to do. I politely asked you to not post the satirical remarks. I have no say in what you post. Now if a moderator thinks you have gone to far, that's a whole different story.

After CAREFUL review of the 22 pages of this thread. I have found 3 post from you which barely stretch toward "serious contributions". The closest I could come up with were pages 1,4, and 13. I almost gave you credit for 1 more, but I forget what page it was on. In contrast (and with out actually counting) you have averaged about if not more than 1 time per page. This leaves you with a 1 in 7 ratio of useful information.

Step off, noob. I will continue to post whatever the hell I want to. Useful, useless, whatever I please.

Here's a bacon donut:

[NicoMoreno]

ArchAngel, George, and anyone else annoyed by the useless posts:
Obviously we need to just ignore the troll until the moderators step in.

[Arch_Angel]

As I see it the spring force of the cork between the socket and the tenon is just as likely to produce the same force (Psi) as the thread wrapping. I'm more inclined to believe that minor "unknown" damages accumulated over time, and now are more apparent. One such force I can think of is a century of humidity (w/subsequent expansion and contraction) changes while remaining in the same position (there by adding more force to one area of the tenon.

[MTGuru]

Kill me ... kill me now ...

Am I dead yet?

OK, temporarily locked for, er, review. And no PMs, please. Thanks.

[MTGuru]

Here's my moderator's take on this thread-thread. There are essentially 2 sub-threads running here.

1. Terry's experimental approach to determining the effect of thread tension on deformation under specific, controlled conditions.

2. The attempt to describe the physics of this deformation as an engineering problem, in appropriate physical and mathematical terms.

I see nothing wrong with number 1. It's a problem of personal and professional interest to Terry, and he is being kind enough to document and share his effort with the Chiffboard community, as well as on his own site. You can follow it, comment on it, or ignore it as you see fit.

As for number 2 ... The argumentation on "both sides" strikes me as weak and unconvincing. Clearly, the problem statement is well-defined, involving materials and geometries which are also well-defined. Which means that there is one and only one correct analysis to describe the forces involved, and not a question of debate or conjecture. A qualified engineer should be able to explain the empirically observed deformation under thread tension in rigorous, unambiguous terms.

To my eye, having a distant background majoring in physics, none of the analyses presented here would pass muster as solutions to a first-year engineering course problem set assignment, much less as definitive answers. None of the presenters convinces me that they have the necessary qualifications to correctly understand and analyze the entire problem - though I'm sure some of the individual points made have merit. And I sympathize with both commenters and silent observers who may find this long discussion to be at least frustrating.

If I were building, say, a tensile-wire wrapped conduit for pressurized natural gas, I'd have zero confidence that any of the analyses here wouldn't result in a massive fireball of destruction.

So let's cool the argumentation and rhetoric. I suspect the piecemeal arguments here have gone about as far as they can go. I'll reopen the thread soon so that Terry can continue to report on his experiment. I would suggest to Terry that, having raised the issue, enlisting the professional expertise of a qualified engineer might be more vigorously pursued, whether your retired friend or someone else. I know one Chiffboard member who is a professor of materials science at a major university, and perhaps I can draw his attention here, but no guarantees.

Meanwhile, if anyone here feels they have the chops to do a full write-up that can pass engineering review, with properly annotated justification of the maths and physics involved and not just hand-waving and finger-wrapping, I say have at it. This might be best done off-site, with a link to the paper, if the board format won't accommodate the graphics and notation.

Thanks ...