I just looked at your board (nice). I’ve been wanting to use carbon fiber on one for a while now. I’ve used it building aircraft parts but always thick, stiff material. I was wondering how difficult you found it to work with. Any tips you could give me would be helpful; I’ll be doing it soon. I was thinking to save $ one full sheet each side and one glass on top. Man, I know you spent some major $$$ for that much kevlar/carbon cloth but, hell, you’re BULLET PROOF! How does it ride? JR
Yes, it did cost some bucks. ($41./sq yd.). However, there are cheaper versions to buy. For example, 100% carbon or 100% Kevlar can be purchased for half of what I spent. The reason I used the fabric I did was because: a.) the carbon adds stiffness while the Kevlar adds dent/ding resistance. (I wanted to build a light, ding resistant board.) and b.) the “crow foot” blue on black looks really cool. I think the ultimate would be to build a styro/epoxy board with one layer of this stuff. Maybe Noodle or one of the other epoxy guys will do this. Any takers? Anyway, because the fabric is woven it is actually easier to use than S or E glass in some respects. Mainly, that the fabric conforms to the rail shape more readily. As far as wet out was concerned; I found that it did take a bit more time to fully saturate the cloth. So, you will want to slow down your cure time as much as possible. Remember that a 5.8oz layer of this cloth actually has at least twice the volume of conventional cloth of the same weight. So, I imagine that the wet out would be like trying to saturate a 12oz layer of S-glass. As far as how many layers to use and of what type; that depends on the person. For me, I like to ride light boards. So, I used 1 layer top/bottom with a deck patch of the same material. However, I am not sure the deck patch was necessary. (The areas without the patch are so hard that the “thumb and forefinger test” becomes irrelevant.) The only advice I could offer is to buy an extremely sharp pair of scissors. (This stuff was really hard to cut.) I recommend doing lap cuts, because the Kevlar laughs at the Sureform. Also, a new Forstner bit for the FCS plugs would have been nice. It took a lot of pushing to get the bit through the cured layer. As far as bullet proof, I’m not too sure about that, but I did experience something strange… After laminating, I carelessly turned while holding the cured board and bashed the nose into the edge of the garage door frame. Horrified, I expected to see large gash in the nose. But there was nothing there! In fact, the board chipped and splintered the wood frame that surrounds the door. As far as how it ride… This will take some getting use to. It turns without forgiveness. What use to be second nature has become a little weird. I think in time I will like it more but for now I am undecided. You can buy Blue, Red and Yellow Kevlar/Carbon from: www.Carbonfabric.net in Hawaii. Ask for Hugh; he has experience building boards and can offer you some good advice. Good Luck and be sure to post pics. when you are done! http://www.carbonfabric.net/
Thanks for the recommendation, but I’m not really looking for glassing work. I’ve never glassed in carbon or kevlar, but I’ve read some about their properties in comparison to E glass and S glass. They are supposedly slightly more flex resistant than S glass, which is slightly more flex resistant than E glass. However, when when you exceed the flex tolerance of carbon and kevlar, it snaps. It snaps at a lower bending pressure than either S glass or E glass. Two of the biggest threats to surfboards are snapping and deck dents. Strong surfboards come in two formulas, weak glass over strong foam, and strong glass over weak foam. Poly boards put weak glass over strong crushable foam. When the foam does depress, the glass just sinks into it. Epoxy boards put strong glass over weak springy foam. When the glass and foam depress, they spring back together. It seems that a fiber which resists springing, but breaks when sprung too hard would not fit well into the epoxy surfboard formula. One of the biggest problems with poly boards is how easily one or two layers of polyester resin doped glass dings. The biggest reason is the polyester resin. Epoxy is probably more than twice as strong. The other reason is how thin the glass is. Using Eposy resin with 2 to 4 layers of E or S glass solves the ding problem and provides the correct surface for putting over a styrofoam blank. Using one layer of carbon or kevlar with epoxy resin would make a lighter weight surfboard. However, over styrofoam, carbon and kevlar would make a surfboard less resistant to deck dents and snapping. For a little more glass weight, you can use cheap glass an have a stronger board than a kevlar or carbon board. …just my opinion.
While I respect your opinion, your facts are a bit off. The below link will take you to a comparison table which compares the tensile strength and modulus of similar densities of laminates. Tensile yield strength is the maximum engineering stress, in MPa, at which permanent, non-elastic deformation begins. Tensile, or Young’s modulus, is the ratio of stress to strain within the elastic region of the stress-strain curve (prior to the yield point). In this case, carbon and Kevlar has tensile strength that is 5 times and 1.5 times that of a similar density of fiberglass. When considering modulus, carbon and Kevlar can withstand 7.5 times and 2 times the amount of stress-strain that of a similar density of fiberglass. http://www.fibreglast.com/UsefulCharts/PhysicalPropertiesOfLaminates.htm http://www.fibreglast.com/UsefulCharts/PhysicalPropertiesOfLaminates.htm
I’ve had a computer meltdown, and lost my “favorites” file. I looked through my current set of bookmarks and couldnt find the charts I’ve read for surfboard fabric comparison. However, a quick Google search yielded this sheet which turns your chart over. I’ll keep looking for surfboard comparison data. http://www.google.com/search?q=cache:RT1IIo93utU:www-nehc.med.navy.mil/downloads/ih/tm91-6.pdf+hexcel+kevlar+S-glass+strength+chart&hl=en
I looked through the link you sent. I am guessing this is someone’s term paper or something. Not to be argumentative, but I did not find anything that “turned over” the comparison chart from Fiberglast. On the contrary, it seems to support it. However, I did not read the whole thing. (it was overwhelming my browser) Below are two quotes regarding the structural properties of Kevlar (Aramids) from your source. I did not see anything regarding carbon. (Page 9) It has been shown that Kevlar® 49 has the highest strength to density ratio of the available reinforcing fibers (Parker, 1990). (Page 20) Aramids have the highest overall strength to density ratio of the composite reinforcing fibers. In fact, Parker (1990) states that aramids are five times stronger than steel. Unfortunately, their transverse strength and their stiffness to density ratio are relatively low. The stiffness is less than that of carbon and between that of glass and steel. Though much lighter than glass, aramids will absorb more energy before breaking. Furthermore, I don’t know why Fiberglast (one of the largest suppliers of laminating materials) would misrepresent the products they distribute. If you would like to look at another comparison check out: http://www.carboncomposites.org/compare.html http://www.fibreglast.com/UsefulCharts/PhysicalPropertiesOfLaminates.htm
Can i get in on this thread? this is super interesting because i love engineering talk about composites.>>> I’ve never glassed in carbon or kevlar, but I’ve read some about their > properties in comparison to E glass and S glass. They are supposedly > slightly more flex resistant than S glass, which is slightly more flex > resistant than E glass. However, when when you exceed the flex tolerance > of carbon and kevlar, it snaps. It snaps at a lower bending pressure than > either S glass or E glass. I think what you mean to say in the previous paragraph is that carbon and kevlar fail catastrophically at a lower bending displacement or deformation which is most certainly true. There are two factors we should be interested in young’s modulus (stiffness) and yield strength (pretty much the breaking strength since these composites fail in a brittle manner). any type of glass has the lowest stiffness and lowest breaking point. kevlar has the highest yield point followed by carbon which is second. carbon is by far the stiffest followed by kevlar which is not too much stiffer than glass. while the glass composite will deform through a larger displacement (deeper heel dent) without failing (cracking and separating) it is not the strongest. you night be surprised to find that a carbon kevlar lamination failed after a displacement of for example 1/8 inch. however had you applied that same amount of force to a glass board your foot would have gone clear through it. having said all this since a graphite board would be almost impervious to flexing (mega stiff) it may not be the best for surfboard design since flex seems to be pretty important to the overall picture.
Trev, you bring up some very valid points, on matters that I really don’t know that much about. However, with regard to “flexing”, or lack there of; this may be the reason that I am not completely sold on how the board rides. Like everyone else, I grew up riding urethane/polyester boards that flex. So, the board may in fact work great and I am just not accustomed it yet. I think this may be the main reason that styro/epoxy boards have not gained more acceptance yet. They too have been accused of not flexing. But, those that ride them get beyond this at some point, and then enjoy the benefits of what I think is in fact a superior laminate schedule. Flex is a strange thing. I really did not give it much attention until recently. It’s one of those things you don’t notice until its gone. In the case of a dying surfboard; it usually losses its flex slowly over time, almost imperceptibly. (unless it breaks) Over time, more and more energy is absorbed by the board rather than rebounding it. In the case of the carbon/Kevlar board I built;I can say that it is not a “dead” ride like when a surf board dies. This is why I described the ride as unforgiving. The best description I can give is that the board knifes through a bottom turn with very little room for error. Having known this before, I might have made the rails a little softer. However, I purposely designed this board to duplicate an 8’6" I built from one layer of S-glass and Ortho. polyester resin the year before. Unfortunately, (or fortunately depending how you look at it) this board is on its way out due to a light glass job and a lot of use. With regard to carbon and its structural properties, one only need to look at its many uses ranging from aerospace, racing car chassis, to bicycle frames to recognize its validity as a structural component. (I have never seen structural parts of any of these things made from fiberglass.) An example closer to home would be its wide acceptance in the sail board industry. Regarding Kevlar, I know that its strength properties are not nearly that of carbon. However, the reason I think it would be a valid material for surf board manufacturing is the same as why canoe an kayak builders use it so often. It’s abrasion resistance is very high. One only need to try to cut the stuff to figure this out. Kevlar can be scraped over jagged rocks with out ripping. This reminds me of the time I had a bad experience with a granite jetty at Fish Pass. The jetty mercilessly tore into a very heavily glassed board. While the board did not break it did get some large gashes in it (as did I). It actually mystifies me why the surf board industry has been so slow to adopt new material technologies while the sailboarders have been using styro/epoxy vacuum bagged Kevlar and carbon technology for some time. The only reason I can figure is that some board builders have very large egos and they get stuck in their ways. The other reason I can think of is cost. However, cost has not stoped some epoxy builders from demanding $8,000 or more for their boards. Speaking(writing) of cost, the cost of the fabric I purchased last year has dropped significantly. If fact, US Composites has the same fabric for $25 / lin. yd 50" wide. Fiberglass Supply has 4.8oz plain weave carbon for $8.50/ lin. yd… So, the cost argument is not as relevant as it once was. I too have been “stuck” on Clark blanks and polyester resin for some time. However, this thread has motivated me to consider a styro/epoxy carbon/Kevlar vacuum bagged board as my next project. Although this will have to wait a little while as I have just finished another board and I promised my wife that I would give it a rest for a while. When I do, I will likely have many questions for folks like Noodle who while I disagree with I still respect his willingness to do something in a different way. Until then, maybe you- Trev, JR or someone else will pick up the mantel. Sorry for the book… http://www.uscomposites.com/
Trev, you bring up some very valid points, on matters that I really don’t > know that much about. However, with regard to “flexing”, or lack > there of; this may be the reason that I am not completely sold on how the > board rides. Like everyone else, I grew up riding urethane/polyester > boards that flex. So, the board may in fact work great and I am just not > accustomed it yet. I think this may be the main reason that styro/epoxy > boards have not gained more acceptance yet. They too have been accused of > not flexing. But, those that ride them get beyond this at some point, and > then enjoy the benefits of what I think is in fact a superior laminate > schedule.>>> Flex is a strange thing. I really did not give it much attention until > recently. It’s one of those things you don’t notice until its gone. In the > case of a dying surfboard; it usually losses its flex slowly over time, > almost imperceptibly. (unless it breaks) Over time, more and more energy WOW!.. what great info…and at a time that i have looking into composites…i was just pricing kevlar/carbon composite weaves…at $25.00 a yard…humm…arn’t there other composites?..I used to see k-glass???.was that s-glass with kevlar weaved into it??? has anyone worked with it?..that board is 3rd in line so i’ll keep you posted…more info is always appreciated!!!..good book…bj > is absorbed by the board rather than rebounding it. In the case of the > carbon/Kevlar board I built;I can say that it is not a “dead” > ride like when a surf board dies. This is why I described the ride as > unforgiving. The best description I can give is that the board knifes > through a bottom turn with very little room for error. Having known this > before, I might have made the rails a little softer. However, I purposely > designed this board to duplicate an 8’6" I built from one layer of > S-glass and Ortho. polyester resin the year before. Unfortunately, (or > fortunately depending how you look at it) this board is on its way out due > to a light glass job and a lot of use.>>> With regard to carbon and its structural properties, one only need to look > at its many uses ranging from aerospace, racing car chassis, to bicycle > frames to recognize its validity as a structural component. (I have never > seen structural parts of any of these things made from fiberglass.) An > example closer to home would be its wide acceptance in the sail board > industry. Regarding Kevlar, I know that its strength properties are not > nearly that of carbon. However, the reason I think it would be a valid > material for surf board manufacturing is the same as why canoe an kayak > builders use it so often. It’s abrasion resistance is very high. One only > need to try to cut the stuff to figure this out. Kevlar can be scraped > over jagged rocks with out ripping. This reminds me of the time I had a > bad experience with a granite jetty at Fish Pass. The jetty mercilessly > tore into a very heavily glassed board. While the board did not break it > did get some large gashes in it (as did I).>>> It actually mystifies me why the surf board industry has been so slow to > adopt new material technologies while the sailboarders have been using > styro/epoxy vacuum bagged Kevlar and carbon technology for some time. The > only reason I can figure is that some board builders have very large egos > and they get stuck in their ways. The other reason I can think of is cost. > However, cost has not stoped some epoxy builders from demanding $8,000 or > more for their boards. Speaking(writing) of cost, the cost of the fabric I > purchased last year has dropped significantly. If fact, US Composites has > the same fabric for $25 / lin. yd 50" wide. Fiberglass Supply has > 4.8oz plain weave carbon for $8.50/ lin. yd… So, the cost argument is not > as relevant as it once was.>>> I too have been “stuck” on Clark blanks and polyester resin for > some time. However, this thread has motivated me to consider a styro/epoxy > carbon/Kevlar vacuum bagged board as my next project. Although this will > have to wait a little while as I have just finished another board and I > promised my wife that I would give it a rest for a while. When I do, I > will likely have many questions for folks like Noodle who while I disagree > with I still respect his willingness to do something in a different way. > Until then, maybe you- Trev, JR or someone else will pick up the mantel.>>> Sorry for the book…