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Carbon Fiber project...


robedney
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I'm working on developing a carbon fiber violin at a reasonable price. I'm not trying to replicate the sound of a classic Italian instrument, but I am trying to produce a highly playable instrument that is nicely balanced and well voiced. I've no illusions of replacing wooden instruments, but rather building an incredibly durable instrument as a second violin and/or student instrument. I've done lots of research into violin acoustics/physics and I've come to a starting hypothesis as I prepare to produce the first prototype (the molds are nearly finished).

What I'd like to do here is to hold that hypothesis up for inspection and get some feedback. Feel free to rip me to shreds!

This will be a tad long, many of you already know most of it, but not nearly as long as it could be. I'll keep it as simple as I can:

First, I've come to believe that plate tuning is a fascinating subject but largely unsubstantiated. From an historical perspective, I find it a dubious notion that any of the "masters" tuned their plates. Plate tuning also -- to my mind -- totally fails to take into account the complete physical structure of the violin. In other words, tuning plates is interesting but it all changes as soon as you assemble the instrument.

Secondly, I've come to believe that what the masters did was to work within the parameters of the violin shape to produce an instrument that had volume, decent tone and durability. They worked empirically, so the emphasis would have been on retaining what worked and discarding what didn't.

Thirdly, I strongly suspect that there was (and remains) an effort to produce volume while retaining structural integrity. A thinner plate will -- all other things being equal -- vibrate more freely than a thicker one -- and greater amplitude of vibration directly equals greater volume. I realize that this is an oversimplification, but give me that for the moment. Following, then, is the process of removing as much material as possible. Clearly, more material can be removed in some areas than others, simply because the physical stresses on the top plate are far from evenly distributed. This -- I tend to think -- is the causation behind what we call graduation.

The violin is challenged with -- simply put -- being loud enough to serve as a solo instrument in front of a full orchestra. In theory, again all other things being equal -- the traditional makers' violin with the greatest volume will be the most sought after instrument (remember that I said "all other things being equal"). I raise this point because I think it sometimes missed in all of the theoretical discussion. A violin that perfectly replicates the sound of one's favorite Strad but lacks sufficient volume is perhaps useful as a parlor instrument -- but that's about it.

Again, the violin's shape is the -- I think -- empirical evolution of a physical structure designed to be as light and sonically efficient as possible. The weight having more to do with acoustical efficiency than the physical needs of the player.

Some makers found a solution that worked well enough and simply repeated their efforts to make copies. It seem safe to assume, however, that many makers physically tested plates as they carved by flexing the wood by hand in an effort to determine how much thinning a given piece of wood could tolerate. It's also safe to assume that the more innovative makers tested the limits to the extent of top plates cracking immediately or soon after setup -- therefore empirically arriving at the limits of the thinning process.

Now, I am not denying that graduation has an effect on far more than the volume of the violin. Clearly it impacts voice as well, and makers would have taken this into account. However, there are real limits to how much "wiggle room" there is between sufficient volume vs. sufficient physical strength, and all makers work within those limits.

All of this leads me to another conclusion -- that being that the specific materials being used have a lot more to do with the tonal quality of the instrument than anything else does. Again, all other things being equal, it is the variation in the characteristics and the structure of the wood itself that accounts for much of the variation in tonal quality from one instrument to the next. This is not news to anyone here. However, part of this has to do with not just the acoustical properties of a given piece of wood but also with the physical strength. A stronger piece of wood could, then, be thinned more than a weaker sample.

So, my understanding being what it is, I need to apply this to the very different physical characteristics of carbon fiber. What I want to do is to hold my starting point up to scrutiny. What do you think?

Be well,

Robert

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Sounds like a worthy endeavor. There are other makers of composite instruments and bows, and innovation can be a good thing. Of course, unless a wood/carbon laminate is used, you'll never match the beauty of wood. One thought: Consider going to a cornerless "Chanot" type design. The inside of a well made violin has that shape already, and with the strength of the composite materials, the reinforcement and stiffening provided by the corners might not be necessary. Have fun, and report progress back to us.

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I agree with much of what you present here; It stands to reason that if you use a consistent, uniform construction material for the body, theoretically you should be able to construct instruments with identical tone. Removing the "wood" variable might indeed enable more exacting research into what is the best arching, thickness / graduation to produce a desirable tone with sufficient carrying power.

If these findings were then applied back to a traditional wood instrument, it could be a guide to the maker as to what sort of properties to look for when selecting wood. To be sure this would only be an approximation in the end because wood has an infinite range of variables, but it may do well enough to at least put a maker in the ballpark of what works.

Regarding plate tuning, I do believe there is some merit to this procedure, however I am of the opinion it should be performed on an assembled instrument as there are too many variables that change between a free plate and an assembled instrument.

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Hi Robert, I'm giving my opinions on some of you're ideas. Take them for what they are, just opinions. Hope they help in some way, and that you don't take them as an attack, which is not my intention.

"Thirdly, I strongly suspect that there was (and remains) an effort to produce volume while retaining structural integrity. A thinner plate will -- all other things being equal -- vibrate more freely than a thicker one -- and greater amplitude of vibration directly equals greater volume. I realize that this is an oversimplification, but give me that for the moment. Following, then, is the process of removing as much material as possible. Clearly, more material can be removed in some areas than others, simply because the physical stresses on the top plate are far from evenly distributed. This -- I tend to think -- is the causation behind what we call graduation."------------------------------------------------

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Don't quite agree with this paragraph. Regarding removing as much material as posible, violins aren't as thin as they could be made. In the top, for one, much more could be removed in the upper, lower bouts than is done. If you were graduating a top with the sole purpose of getting rid of as much material as possible, in as many areas as possible, they wouldn't be uniformly graduated. And the backs would have their thickest area under the sound post. None of these examples are done if you're tryin to make a great sounding instrument. I think it's a misconception that violin plates have to be thin, to sound great, and to project. Maybe even the opposite, sometimes.

"The violin is challenged with -- simply put -- being loud enough to serve as a solo instrument in front of a full orchestra. In theory, again all other things being equal -- the traditional makers' violin with the greatest volume will be the most sought after instrument (remember that I said "all other things being equal"). I raise this point because I think it sometimes missed in all of the theoretical discussion. A violin that perfectly replicates the sound of one's favorite Strad but lacks sufficient volume is perhaps useful as a parlor instrument -- but that's about it. "-----------------------------------------

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Don't agree with that, either. If violin aren't loud enough to be heard, then why all the great concertos written for the instrument. Why do people still go to concerts, then?

If you're suggesting that volume is the most important, or the prime goal of a violin, then here's a thought experiment;

Imagine sitting in front of a stage, and listening to an aria being sung by a legendary Tenor ( pick you're favorite) . Now imagine the same, but replace the singer with me screaming at the top of my lungs for ten minutes. Then imagine my four month old on the stage, hungry and tired, with a microphone in front of him.

Quality beats quantity, I think.

"All of this leads me to another conclusion -- that being that the specific materials being used have a lot more to do with the tonal quality of the instrument than anything else does. Again, all other things being equal, it is the variation in the characteristics and the structure of the wood itself that accounts for much of the variation in tonal quality from one instrument to the next. This is not news to anyone here. However, part of this has to do with not just the acoustical properties of a given piece of wood but also with the physical strength. "---------------------------------------------------------

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Here I agree with Oded. You are making the case against c-fiber. Violins mostly sound like the materials that they are made of.

"A stronger piece of wood could, then, be thinned more than a weaker sample"-----------------------------------------------------------------------------

that suggests, for example, that ebony could be used a a top. As long as it's thinned out more?

" It's also safe to assume that the more innovative makers tested the limits to the extent of top plates cracking immediately or soon after setup -- therefore empirically arriving at the limits of the thinning process"---------------------------------------------------

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Not a safe assumption at all. In fact, I'd suggest no serious violin maker would do that.

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Thanks for the responses! To clarify a few things;

It wasn't my intention to say that traditional makers made top plates as thin as they possibly could to the extent of sacrificing sound. Remember I said "all other things being equal", meaning that the thickness of the top plate would be as thin as possible _without_ sacrificing tonal _quality_. This only makes sense -- nearly all design is a matter of compromise. One would want to achieve the best combination of tonal quality and volume. I read somewhere that Stradivarius violins got lighter and thinner as his career progressed. Why, if not striving for that balance?

I said: "All of this leads me to another conclusion -- that being that the specific materials being used have a lot more to do with the tonal quality of the instrument than anything else does. Again, all other things being equal, it is the variation in the characteristics and the structure of the wood itself that accounts for much of the variation in tonal quality from one instrument to the next. This is not news to anyone here. However, part of this has to do with not just the acoustical properties of a given piece of wood but also with the physical strength. "

To which Oded replied:

"This seems like a clear reason not to use carbon fiber."

That might be true if we knew the actual potential of carbon fiber as an acoustical material for violin making, which we don't as yet. Now, I am a profound fan of wood. I've worked with it nearly all of my life. I even prefer wooden boats over the far more practical fiberglass versions. A great wooden boat designer -- L. Francis Hereshoff (sp?) once refered to fiberglass as "congealed snot". However, I also live on a boat (60' of steel) and I've had the experience of a violin neck simply letting go due to the humidity. It's easy enough to reset the neck, but I know how. What about someone who doesn't? I think there is a place in the world for a decent fiddle that can survive in extreme environments.

I'll address one more objection: The suggestion that my approach would argue in favor of using ebony somehow. Not at all. The acoustical properties of ebony are very, very different than those of spruce -- as is the strength to weight ratio. In fact, spruce has -- for practical purposes -- the highest strength to weight ratio of any commonly available wood (remember the "Spruce Goose"?). It makes sense, then, that it is the king of woods for the top plate of a violin. Carbon fiber (at least the specific carbon fiber lay-up I will be using) has a strength to weight ratio far, far higher than spruce. It wouldn't make sense to ignore it as a potential violin material.

There is a valid argument to be made that if it's not made of spruce, maple and ebony it's not a violin. I'm sure there was also a time when a valid argument was made that if the strings weren't made of gut it wasn't a violin. I am biased towards wood. However, there is undeniable existing research that suggests that string instruments can be made from carbon fiber that sound every bit as good as a decent counterpart made from traditional wooden materials. Can a truly magnificent instrument with astonishingly great tone and ideal dynamic range be made from carbon fiber? I actually kind of hope that the answer to that is no. However, if the objective is great sound and playability, ought not we to explore the options?

I know that it is easy for me to forget at times that the actual goal in making is to provide a musician with a means of making music. It's the sound and the playability that matter most (which is in now way to say that musicians do not have profound relationships with their instruments, as well as sometimes lovable but eccentric biasis regarding them).

Cheers,

Robert

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Re: use of carbon fiber for instruments

That might be true if we knew the actual potential of carbon fiber as an acoustical material for violin making, which we don't as yet.

I'll limit myself to this corner of the discussion but I agree with Darren on his objections.

There has been a fair amount of work done with carbon fiber for instruments. These days the most successful ones seem to be sandwiching wood between cf.

I'm quite open to experimentation. I've built a couple of experimental balsa instruments. I would look elsewhere for suitable construction material. I think epoxy is too dense and has some nasty acoustical properties. Perhaps a composite using cyanoacrylate (krazy glue). Whatever material you choose it should have some inherent or added damping properties.

Oded

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I think it is an interesting project, however this quote isn't 100% true:

"That might be true if we knew the actual potential of carbon fiber as an acoustical material for violin making, which we don't as yet. "

Luis and Clark has been making carbon fiber instruments for some time. From what I understand, they are rather successful with their cellos, but the violins haven't really caught on.

http://www.luisandclark.com/violin.php

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I also don't want to come across as being against experimentation of this sort. I think it's quite fun to think about, and I hope you post pictures as you progress. I'm only pointing out areas where I think the ideas might not contribute to success.

Oded pointed out an area which I also agree needs to be addressed. My thinking is that the epoxy is the more important element of c-fiber acoustically. And also to abandon the carbon fiber that comes in any sort of weave or uni-directional form.

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I think it is an interesting project, however this quote isn't 100% true:

"That might be true if we knew the actual potential of carbon fiber as an acoustical material for violin making, which we don't as yet. "

Luis and Clark has been making carbon fiber instruments for some time. From what I understand, they are rather successful with their cellos, but the violins haven't really caught on.

http://www.luisandclark.com/violin.php

Yes, I'm aware of the Luis and Clark instruments. I nearly bought one (subject to approval) -- and that's what put me on the road to experiment. I've never actually laid hands on one and I don't want to (because I don't want to be accused of copying -- they are somewhat secretive). I asked if the top were graduated as in a traditional violin and was told -- very nicely -- that they would not say.

I have a theory (and it's just a theory) that given the success of the cello they moved into the larger string family, including the violin. Clearly the cello is a great success, indicating that carbon fiber works well in that application. However, the violin is a much trickier instrument given its considerably smaller size and the need to produce sufficient volume from that size. I'm admittedly guessing, but I suspect that the top is not graduated (why else would one decline to answer that question) and that perhaps they stopped developing the instrument once they got to a certain point. It's a small company and they seem to trade mostly in the cellos.

I'm contemplating scores of top plates in varying densities and other variations as I go at this, a long process. There is also the possibility of oriented strands of carbon fiber, which would somewhat mimic the characteristics of the grain in spruce. In other words, there is a lot that hasn't been investigated.

Oded: I agree to a point regarding epoxy, however the Luis and Clark cello is an epoxy/carbon fiber composite and seems to work quite well. My beginning assumption is that the top plate (as opposed to the rest of the instrument) will need to be cured under a great deal of pressure, therefore leaving just enough epoxy to fully bind the carbon fiber and give it abrasion resistance. Carbon fiber layups are frequently vacuum bagged, and I suspect that's not enough pressure, but we'll see. It is certainly true that too much epoxy unnecessarily lowers the strength to weight ratio, and therefore the resonance.

Robert

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Will you keep corners on it then? I don't know how you're going to avoid suspected copying of L&C with a Chanot style carbon fiber violin.

Nope, no corners. It seems to me that simply using the Chanot shape doesn't imply that I'm copying the L&C. There will also be (at least initially) no scroll, because adding the scroll would require a far more complex mold. L&C eliminated the scroll for the same reason, I'm sure. The peg box is totally traditional in shape aside from the scroll, which allows it to be removed from a one piece mold.

When I refer to copying, I mean the specifics of the carbon fiber layup -- and I have no idea how L&C does that. You might say that the exterior shape is pretty much in the public domain. I also have no idea what they modeled the body after (what maker), if any. Mine comes from an instrument I already had in progress.

Go to http://www.robertedney.com and follow the Carbon Fiber link to see a pic of the shape. It's an instrument in progress -- redirected to CF by cutting off the corners. The back (which is carved from vertical grain fir because it's just a mold) also has it's corners removed at this point, although still showing them in the pic.

The website and pics will get more sophisticated as things progress and I have time.

Cheers,

Robert

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iam in no way an expert on carbon fiber, but i have done alot of car work

carbon fiber shards are extremely sharp, dont go screwing around untill you have proper protection, ive seen shards an inch long imbed themselves in people molding it

what form of carbonfiber are you using?

have you done and carbon fiber work before?

what are your molds made of?

what finish will you be using?

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iam in no way an expert on carbon fiber, but i have done alot of car work

carbon fiber shards are extremely sharp, dont go screwing around untill you have proper protection, ive seen shards an inch long imbed themselves in people molding it

what form of carbonfiber are you using?

have you done and carbon fiber work before?

what are your molds made of?

what finish will you be using?

In order:

Initial layups will be woven cloth with epoxy resin. Will probably experiment with scrim cloth and aligned strands.

Yup, it's sharp. Sounds like you may be thinking of pre-preg CF -- I'll not be doing that. I'll be doing the layup from scratch.

Yes.

Molds are tooling gelcoat with fiberglass mat. Molds back-filled for reinforcement (to take the pressure)

Finish is a good question. I'm contemplating linear (two part) polyurethane, but it may not go on thin enough without finish issues (like pinholing). Aside from that it's incredibly tough stuff. This is still an open question -- ideas? Actually, with good molds and careful assembly/finish work a topcoat may not even be necessary -- aside from the UV protection question with epoxy. Not many fiddles sunbathe, however.

Be well,

Robert

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I wouldn't be to concerned about attempting to duplicate plate graduations as my work with aluminium bodied violins has shown me that a brilliant sound can be achieved without any plate graduation. I would suggest concentrating on achieving similar internal body shape, cubic capacity and completed weight as the initial priorities.

Re Chanot style - probably easier to make and with a reduction in weight, as the internal shape and volumes are the same there should be no loss of tonal qualities.

Good luck with the project.

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Making a carbon fiber cello:

part 2:

Very, very cool. Thanks for the links. It's fascinating that the procedure they use is very close to what I've worked out on my own. I guess there are only so many ways to skin a cat.

The most interesting part of the video to me is the mold for the top plate. It's a two piece mold, and that suggests to me that the top is not of a single thickness throughout -- otherwise vacuum bagging would work fine. Or, it suggests something else that I'm anticipating, that the top plate will be at its best when cured under a fair amount of pressure.

One thing I'm wondering -- and I couldn't quite see -- is if they block off the sound chamber at the neck to body joint, or allow the hollow neck to become part of the chamber. I plan to try both.

It's also interesting that it seems to be all of carbon fiber twill fabric, as opposed to oriented stand or simple square weave. Twill is definitely nicer looking. They didn't show us the top plate layup, so there may be something different there.

I'm not fond of the way the top seems to be attached to the body. Two things: There appears to be a lip on the top that wraps over and covers the seam. Nice for appearances, but hell if you ever need to remove the top. Secondly, that stuff coming out of the syringe is almost certainly epoxy resin thickened and colored with powdered graphite -- again making it hell to remove the top. I suppose the assumption is that the top will never need to come off -- an assumption I'd not be comfortable with.

One thing I've simply got to comment on is the label. I mean, given the rich history of stringed instrument labels, that one has all the romance of a stewed potato.

Anyway, thanks again! I feel enlightened now.

Be well,

Robert

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I haven't looked at the videos yet but how can a label ruin the romance of a violin? After all aren't you casting one of of epoxy and cloth? Carbon fiber violins have a place and a purpose but there is nothing romantic about them no matter what label you stick in them.

Good point. I guess I should say that given the opportunities to make something interesting (and the ease with today's computer graphics), the label lacks imagination.

Cheers,

Robert

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