Carbon Fiber Use In Lutherie

[Allen]

Dave, are you taking the piss out of Kim.

Now I'm going to have to find out what a Toneright is....
_________________
Allen R. McFarlen

[Kim]

Dave White wrote:

Kim wrote:
I don't believe there is any 'benefit' in having any amount of movement what so ever in the UTB and in fact will happily go on record as stating that any movement at the upper transfer brace (UTB) will only sink string energy into the upper bout and neck block thus reducing the effectiveness of the lower bout which, in my opinion is the area of the instrument that is the very essence of a responsive guitar.

Cheers

Kim

Kim,

Big statement there !! Some of us "flat earthers" believe that the upper bout is a very important, if subtle, part of the instruments sound potential - I think that Rick Turner is one too.

It's interesting to read of builders Damascene Conversions on this issue - here's one from Tim McKnight.

I'll pray for you my son

Kim wrote:

Also I should define my earlier statement re; any movement at the UTB being a negative toward accomplishing a responsive guitar.

Should a builder have already countered the rotational force of string tension via buttress bracing back to the waist etc, then i concede that the upper bout certainly can be explored as a way of increasing the effective sound production area of the top. Failing that, it is my opinion that any movement or flex of the top at the UTB will at best 'reduce' the responsiveness of the guitar, and at worst indicate a lack of structural integrity.

Cheers

Kim

Don't pray too hard Dave, i was thinking of you when i wrote the above.

Nice to see you here, i have missed you

Cheers

Kim
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[Kim]

Allen wrote:
Now I'm going to have to find out what a Toneright is.... Confused

Allen,

As i understand, the tonerite is an electrical implement which is sat upon the strings of a guitar and then vibrates to induce a 'play in' affect. It is claimed that a newly strung instrument can be 'played in, and achieve that "Vintage Martin Tone" in a single 72 hour session. This implement vibrates the strings and bridge @ 50hz in the USA and 60hz everywhere else in the world. According to the tonerite people, years of exhaustive acoustic research found that 50hz is the magical number to produce the "Vintage Martin Tone" in the USA. Of course if you live outside of the USA and they sell you a unit then the magic number required to achieve that very same "Vintage Martin Tone" automatically converts to 60hz.

What is most interesting is that these two figures just happen to coincide perfectly with the electrical supply cycles of the countries in which this device will be operated. What is even more outstanding is that 50hz is exactly what a $6 aquarium pump will vibrate at in the USA and 60hz is exactly what a $6 aquarium pump will vibrate at in the rest of the world.

The people at tonerite will sell you one of their highly researched scientific implements for around $150usd plus shipping. If you find that difficult to come up with just after the xmas break and all I will glady wrap a $6 aquarium pump in some inner tube for you and ship postage free for a measly $50...wadaya say huh Cool

F.Y.I. Here is a link to the tonerite site

http://tonerite.com/

Cheers

Kim
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[Lillian]

Kim wrote:

The people at tonerite will sell you one of their highly researched scientific implements for around $150usd plus shipping. If you find that difficult to come up with just after the xmas break and all I will glady wrap a $6 aquarium pump in some inner tube for you and ship postage free for a measly $50...wadaya say huh Cool

Cheers

Kim

Ooo I want one!

[Dave White]

Kim,

I apologise - I should have read further and more closely but when I get to "neutral axis" I start to get pictures of Switzerland in my head for some reason Shocked I'm in Hog Heaven at the moment as I understand that the Laws of Physics as we know them are currently broken, as the equations break down when you get to what's happening at the centre of Black Holes - they divide by zero and become infinity which isn't allowed apparently. And as engineering is based on these laws . . . So I'm with the Quantum Theory where you can be lot's of places at once and nothing is "normal" as we think - this to me is more likely where the Tone Faeries dwell, little things matter a lot. But then I was always a big kid at heart. Embarassed

Jeff

"You can't just put a prop from the top of the neck block to the back at the waist (i Know you do it differently ricK) and think you are dissipating the force there."

I may have got this wrong but I think that the rim set is an incredibly strong structure and making braces that connect the top of the neck block into the rimset just below the waist and into the line of the rimset around the lower bout (whether they are CF or spruce or whatever) strikes me as a better way of dealing with the forces from the neck than trying to glue the fingerboard to the top and bracing the feck out of the upper bout. Taking them from the top of the neck block to the back at the waist and I'm not sure where the forces are going. I also use a pair of CF braces at the bottom of the neck block that are parrallel to the top ones, but I know that Rick thinks that these aren't as effective as they are under tension rather than compression and he uses the CF capped centre method to counter the force trying to flatten the back.

Overall stiffening the rimset and using it to dissapate the string tension forces seems to be a good plan to me

By the way - perversely I also use A frame brces on the top inlet into the neck block and a soundhole patch like Fylde, Lowden etc.
_________________
Dave White
De Faoite Stringed Instruments

Last edited by Dave White on Thu Dec 31, 2009 12:36 am; edited 2 times in total

[Dave White]

Sorry - double post. You see I was two places at the same time Cool
_________________
Dave White
De Faoite Stringed Instruments

[Kim]

Dave White wrote:
I'm in Hog Heaven at the moment as I understand that the Laws of Physics as we know them are currently broken, as the equations break down when you get to what's happening at the centre of Black Holes - they divide by zero and become infinity which isn't allowed apparently.

Sounds like spaghettification boglenese to me Dave Wink
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[Hesh1956]

Lillian wrote:

Ooo I want one!

Lillian that sounds kinky.... again.... Very Happy

Sooooo... Anyone else have any interesting uses for CF in guitar making or anything else that you might do in your shops with the lights low? Smile

Also - how are you gluing/laminating CF to the various woods that we use?

[Dave White]

Kim wrote:
Dave White wrote:
I'm in Hog Heaven at the moment as I understand that the Laws of Physics as we know them are currently broken, as the equations break down when you get to what's happening at the centre of Black Holes - they divide by zero and become infinity which isn't allowed apparently.


Sounds like spaghettification boglenese to me Dave Wink

Kim,

Well put on your napkin, open a nice bottle of Cianti and work your way through these:

Naked Black Hole (This isn't porn, honest)
Physical Paradox
Black Hole Information Paradox
Black Holes

I saw this first on the BBC Horizon science program about Black Holes and was fascinated so it's not all Wikipedia wacky stuff. Apparently you can download the TV programme from this site but I don't know how legal or virus free it is. It's well worth a watch.

I'm fascinated by how new theories and understandings seem to evolve from small things and then go in completely new directions -- you can explain 99.9999% of everything but the 0.0001% blows it all away. Newton's Gravity theory fell on a minute discrepancy of a planet's predicted orbit compared with that observed and Einstein's Relativity emerged. And now Eisnstein is stuck at the centre of a Black Hole.

String Theory seems a very appropriate one for a guitar maker Very Happy

Sorry for the topic divert.
_________________
Dave White
De Faoite Stringed Instruments

[Bob Connor]

Here's what I've done on the latest Hesh.

The CF is glue with Araldite, which is a common garden variety epoxy available in Australia.

I want to stiffen up this area but I don't want to totally deaden it, thus the scallops at the ends of the UTB. Using the A frame braces and the patch around the soundhole is going to make this fairly solid in this area anyway.

FIL26129.JPG (120 KiB) Viewed 25813 times

_________________
Bob, Geelong
_______________________________________

If Becks are a sponsor next year I guess we'll just have to give East Augusta a miss.

[jeffhigh]

Dave White wrote:
Kim,



I may have got this wrong but I think that the rim set is an incredibly strong structure and making braces that connect the top of the neck block into the rimset just below the waist and into the line of the rimset around the lower bout (whether they are CF or spruce or whatever) strikes me as a better way of dealing with the forces from the neck than trying to glue the fingerboard to the top and bracing the feck out of the upper bout. Taking them from the top of the neck block to the back at the waist and I'm not sure where the forces are going. I also use a pair of CF braces at the bottom of the neck block that are parrallel to the top ones, but I know that Rick thinks that these aren't as effective as they are under tension rather than compression and he uses the CF capped centre method to counter the force trying to flatten the back.

Overall stiffening the rimset and using it to dissapate the string tension forces seems to be a good plan to me

By the way - perversely I also use A frame brces on the top inlet into the neck block and a soundhole patch like Fylde, Lowden etc.

Dave next time you have a rimset made up and lined and with any CF bracing in place, take it out an stand it on the tailblock end and sit on it.
Does it break or bend even just a little?
It is missing the most important structural elements, the top and back.
You cannot dissapate string force into other areas, It still has to find it's way back to the bridge

[Dave White]

jeffhigh wrote:


Dave next time you have a rimset made up and lined and with any CF bracing in place, take it out an stand it on the tailblock end and sit on it.
Does it break or bend even just a little?
It is missing the most important structural elements, the top and back.
You cannot dissapate string force into other areas, It still has to find it's way back to the bridge

Jeff,

If I attach the top to the rim and then stand on that then it will probably break too - although Rick T maintains he can stand on the backs of his guitars with the CF centre capping strip. Maybe if I used CF under the side linings like Rick or build matching buttress braces to the tail-block I could stand on the rimset without it breaking too.

OK I used the wrong words - I should have said "counteract the effects of" not "dissapate" and that's what the paragraph before was outlining.

Which part would break or move when I sat on it - the heel block where the buttress braces are applied or the tail-block end where I don't want as much rigidity when the top is glued on? I can certainly not budge the heel-block in the rim assembly with the CF braces in but I can when they are not in place. An elephant could budge it though.

Actually without the top and back it's missing the most important tonal elements.
_________________
Dave White
De Faoite Stringed Instruments

[Rick Turner]

On my guitars, you can do a tap test of upper and lower bouts and get a virtual tweeter/woofer response. The upper bout is definitely happening...and I do not have an upper transverse brace in there killing off upper bout top vibration. I have no need of an upper transverse as the fingerboard is cantilevered and the neck block supported by the flying braces. What I hear is an improvement in harmonic sustain, and the idea that anything is being "drained off into the neck block" is just not happening. If anything, it's the opposite as the upper bout is actively contributing to tonal output instead of being relegated to supporting the neck and fingerboard extension.

Opening up the upper bout has also helped a lot with our ukuleles which are becoming known for their rich and classical guitar-like tone. There's precious little real estate on a uke top, and anything you can do to improve it helps.
_________________
Rick Turner
Guitar Maker, Experimenter, Diviner
www.renaissanceguitars.com
www.d-tar.com

[jeffhigh]

Dave, In your arrangement,With the A frame brace and the carbon fibre stuts, you have a number of different pathways for force
- neck to neckblock to top(stiffened by bracing ) to bridge
-neck to neckblock to struts to sideblock to rims back to top to bridge

anyones guess as to which ends up carrying the bulk of the load

[Mike Thomas]

I have no experience of carbon fibre in guitar making, but I do have over twenty years of experience in the use of carbon fibre in FAI (international class) free flight gliders. Just to establish some credentials, I have made carbon and other parts for wings for several participants at world championship level, including the second placer at the 2009 World Championships. The wings on these gliders are around 2.5 metres span, and the main structural element spanwise, is a spar which consists of a balsa core, capped top and bottom by 1mm thick unidirectional carbon, glued on with epoxy (usually West Systems, not Araldite which is too thick), or thick CA, which works well. The spar at the centre of the wing is about 9mm in height and 10mm wide, and tapers out to the tips. When the glider is launched, it is accelerated to very high speeds and the wings bend alarmingly under the load. They return immediately, and perfectly, to the unloaded position on deceleration.
It seems to me that the spar in an aircraft, and the brace in a guitar share some functional similarities. They both need to be light but strong, and they both need to flex and then return immediately to their original position. It seems, from my non-guitarmaker's experience, that balsa may be better than spruce for carbon capped braces, because of its lightness (a third of the weight?). Also, and this is very significant, the balsa in a wing spar has the grain oriented vertically, not spanwise i.e., the carbon is separated by endgrain balsa, because the function of the balsa core is to resist compression, not provide spanwise strength. The carbon does that. I would be surprised if it hasn't been done already, but it would be interesting to try braces made in a similar way.
_________________
Mike Thomas


"There are some enterprises in which a careful disorderliness is the true method"

[Rick Turner]

Mike, Greg Smallman does exactly that...he caps balsa braces with CF. I've done that in a couple of ukes as well, and it works as you would think. Greg's issue is that there is no room for error, and if he decides he doesn't like the sound of a guitar top, off it comes and off to the tip with it, and he's lost dozens of hours of labor. One thing we can do with more traditional top bracing is to recarve it post-build. So maybe the trick is to use CF topped braces where there's little chance that they won't work...at least that's been my approach...and use more or less traditional bracing where you do have the opportunity to get in and regraduate it.

I don't want to work blind carving or sanding CF through a soundhole!
_________________
Rick Turner
Guitar Maker, Experimenter, Diviner
www.renaissanceguitars.com
www.d-tar.com

[Mike Thomas]

Thanks Rick. I was wondering, more specifically, if anyone has used balsa with the grain oriented vertically. The rationale being that 6lb /cu. ft. balsa with vertical grain may well be as effective in resisting compression as 12lb /cu.ft balsa with the grain oriented conventionally. How do you and Greg do this?
_________________
Mike Thomas


"There are some enterprises in which a careful disorderliness is the true method"

[Allen]

I went searching for Balsa today on line and see that there is a ready source for the wood cut as you are describing Mike. Must be fairly common to use it like this.

Makes me think that if you are only using it as a spacer material between CF then does it matter in what direction the grain is going? Especially if you are doing as David Schram is with the CF Tow on both sides of the lattice.
_________________
Allen R. McFarlen

[Kim]

Just thinking about it and in my minds eye, it would seem to me that gluing CF either side of the end grain may make the beam 'too' stiff as the short strands of wood fibre running between the the layers would be locked allowing next to zero flex. I guess it is another one of those things you would need to experiment with to find out for yourself.

Cheers

Kim
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[DarwinStrings]

I like that log approach in the Maton Kim, looks like you kept it off the soundboard too, interesting food for thought.

Jim

[Antipode]

End grain balsa has been in use by boat builders for yonks. Came out as cubes on glass mat. Would form to free form curves on the mat. Add epoxy to fill the cavities, add another layer of mat to the other side and more epoxy and you have an I- beam structure that is very strong in compression, through the end grain balsa, and in torsion/flexing through the separated glass layers. The Nomex model is mechanically the same, so is the lattice braced top, the honeycomb glass or ali used in (now old) monocoque tubs for race cars. Just different materials mated to create the I-beam effect.
It is the separated distance between the non-stretching, non-compressing layers that give strength/rigidity in the direction of the separation. In terms of balsa and glass or carbon fibre, the balsa is just the separation. That it is light is the bonus.
Rick
_________________
Time was on my side but the relationship is feeling a bit shakey Smile

[Hesh1956]

Not to high-jack the thread from the jerk who started it but having worked with lots of balsa for radio controlled aircraft it just seems to me to be a wood that might be a tone sink and not a tone transmitter....

It's very soft and the difference when using thin CA is very notable with balsa smoking a lot and other woods that are denser not smoking.

I'm in the camp that the top braces transmit vibration as pathways of sorts - when does a wood species become too soft and porous to be used as braces in a capacity where there is a structural AND tone transmitting expectation.

Make no mistake I am not being critical of Smallman - he is an incredible builder and designer. But for conventionally built guitars, what most of us do here, I am wondering if balsa might not be as efficient as spruce for vibration transmission.

[Mike Thomas]

Hesh, I'm sorry if you feel that yor thread has been hi-jacked by my introducing the issue of carbon/balsa bracing. But you did ask "let's see what folks are doing with CF and Lutherie, and perhaps more importantly, why?"
You will know of, or perhaps even know, Joseph Curtin, a very prominant U.S. violinmaker, and coincidentally, also a resident of Ann Arbor, He wrote the following in the April 1999 issue of The Strad magazine (it's reproduced on his web site)

"If one is interested in increasing power and response, the best strategy is to reduce the weight of the vibrating components, while maintaining an appropriate stiffness. For a traditional instrument this is most plausibly done by choosing wood of a lower density.........A more innovative approach........is to place thin layers of very strong materials, for example carbon fibre, on the surfaces of a lightweight core.......a very light wood such as balsa.This allows a vast increase in the stiffness to weight ratio"

Hesh, I suspect that most instrument makers, initially at least, doubt the acoustic properties of balsa. But we are not dealing with balsa on its own, but with a balsa/carbon composite. Joseph Curtin goes on to say "For a violin maker, the trick is to balance the acoustical characteristics of these various materials in order to optimize the sound of the finished instrument"

That it is possible to make good sounding instruments out of carbon reinforced balsa, and little else, has been proven by Doug Martin, another U.S innovator. He has spent a long time developing balsa/carbon violins, and although aesthetically they leave something to be desired, they sound very convincing. In a recent blind sound test of recordings of three violins, some very experienced listeners preferred the sound of the balsa/carbon violin to the other two, one of which was a Guarnerius Del Gesu, and the other by a modern maker using traditional materials.
_________________
Mike Thomas


"There are some enterprises in which a careful disorderliness is the true method"

Last edited by Mike Thomas on Fri Jan 01, 2010 12:40 pm; edited 1 time in total

[Hesh1956]

Hi Mike and thanks for that. All good points and no disagreement from me.

I certainly do not contend that there are not indeed other materials that can produce sound in the context of being part of the structure of a guitar.

I know of Joseph and know people who know him and he is very respected.

Where I do beg to differ is my original contention that although other materials may be superior in some of the qualities that we seek such as stiffness, low mass, etc. do they sound like what one's expectation is for how a guitar should sound.

Even Joseph in the quote above says that the "trick" is balancing the acoustical characteristics. It would not be difficult to design and build a guitar entirely out of CF, Kevlar, perhaps throw in some titanium as well that would structurally out perform a traditionally built guitar built from traditional materials but.... would it sound like a guitar? That's my point.

It's generally pretty well accepted by guitar builders who are interested in flirting with the so-called line of implosion that a guitar that either has a top that is too thin or is too lightly braced or both will sound thin and weak. Why is this? Certainly the plates, top and back, may be flapping about just as much as a heavier built guitar if not more.

Is it perhaps because there is not enough material to vibrate to the degree that it produces the volume of sound that is desirable in a high-end acoustic guitar.

Anyway I never wanted to get creative and explore alternative ways to build a guitar until I at least believed that I had a pretty good understanding of how a conventionally built guitar really works. The more I learn the more I understand that I have a LOT more to learn and that the folks who really understand how an acoustic guitar really works are few and far between.

So that's the attraction for me and it's a goal that I will never reach in this lifetime but perhaps when I come back as a worm I can at least eat some Brazilian Rosewood before you guys get to purchase it... Very Happy

[Rick Turner]

Comment re. vertical grain (or end grain or however you want to describe it) between CF skins. You can design them to have whatever degree of flex you want just by...well, the word is "design". With CF you have a certain degree of liberation from stiffness, toughness, tensile strength and all being part of a whole; you have the ability to use different qualities in different ways that is hard to do with a single material like wood. Of course, more choices means more ways to screw it up, too!

Smallman and Curtin seem to have dealt well with balsa's damping factor, too.

This gets into the area where too much thought and too little hands-on experimenting and experience gets in the way of the truth.
_________________
Rick Turner
Guitar Maker, Experimenter, Diviner
http://www.renaissanceguitars.com
http://www.d-tar.com


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