So im shaping a new stringerless EPOXY shortboard and was interested in doing carbon fiber parabolic stringers. ive done all my shaping except the rails/tail. my question is:
Should i glass the carbon fiber onto the rails before the rest of the board is glassed, then sand and flush the rails into shape.
or
should shape the rails completely, then glass the board stringerless, dry it, then sand the rails and glass the carbon fiber on?
or
neither and i should do something different.
thanks
hi Bigwadda, welcome to Swaylocks...
Shwuz posted some good info on how he does/did his carbon fiber rails... maybe do a search...
i would laminate the carbon on the foam, then glass over it. you could laminate the blank with one layer of glass on each side, then do the carbon, and then laminate over again but that would be a lot of unecessary work. if you are done laminating before you put on the carbon, it will sit proud. if you are not doing a cutlap, then you could laminate the carbon with the glass at the same time. use some spray adhesive to hold it in place.
Perhaps it was this thread, second post down: http://www2.swaylocks.com/forums/carbon-fiber-rails-how?page=1
[quote="$1"]
[quote="$1"]
hi Bigwadda, welcome to Swaylocks...
Shwuz posted some good info on how he does/did his carbon fiber rails... maybe do a search...
[/quote]
Perhaps it was this thread, second post down: http://www2.swaylocks.com/forums/carbon-fiber-rails-how?page=1
[/quote]
that was it Paulr, thanks!... i wish Shwuz would come back around he always had some nice boards to post... last i heard he was in Alaska?
I’m going to go against the grain and say don’t. I have used carbon on the rails of a longboard and short board and I just don’t think it has any function on the rails. Here are the negatives as I see them: not compatible with standard glass from a strength of materials standpoint, it will snap before it will bend, since rails get most of the dings you will see a lot of hard to repair fractures, it aint easy to work with and cutlaps take very advanced skills (can be done, tho), and lastly and my favorite: they get hot as a son of a gun in the heat of summer and will burn your hand and make you use potty talk in front of others.
In short, a lot of work for questionable return. Let the arguments begin.
all the best
Interesting point, this design would be for a performance shorty, mostly for head high punchy waves and airs, i have other designs for heavier waves. really i wanted the carbon to trim weight and add some spring out of turns. i was also considering balsa rails, but thought carbon would be easier just doing a cutlap.
quesntion 2 now…
in the peoples opinon which has a better release, carbon or balsa?
Bamboo
I always wonder why nobody uses kevlar instead of carbon for the rails. Of course, carbon looks kinda cool. But kevlar is known for very good energy absorbing (used in bullet proof vests), so it should be great for avoiding dings on the rails. I heard it sands very bad, so it should be put under the glass. Its hard to cut thou, so probably use a tape:
http://shop.r-g.de/Verstaerkungsfasern/Aramidgewebe/Aramidband-180-g/m.html
Carbon is strong but stiff. You need to keep it near neutral axis if you don’t want it to take all load. Because of stiffness carbon have low impact absorption so you need to protect it and to support it with material with better impact resistance. On rails carbon need to be encapsulated.
So why use carbon ?. Because carbon is the better material for dynamic load resistance. In a studdy on helicopter blade, those who contain carbon didn’t brake during fatigue test, and the most interesting aspect was stiffness keeping even if blade was impacted:
In a composit with glass fiber in same direction than load, during fatigue test, you see that stiffness decreases quickly (micro craking of resin) then stiffness decrease slowly (wear of fiber) until breaking. In carbon composit, the first stiffness decrease is very reduce and wear of fiber very slow.
If correctly use, a bit of carbon on rails can be a good think to improve dynamic flex durability of surfboards.
Sorry for my frenglish
[quote="$1"]
use some spray adhesive to hold it in place.
[/quote]
Grasshopper
Would permanent spray on carpet adesive work? Would it not mess with epoxy?
Cool tip! Many thanks!
Adhesive sprays on EPS foam will melt the foam....that will cause potty talk.
Kelvar is bullet proof...have you ever tried to cut it..and then cut it when it's dried with epoxy...............that to will cause excessive potty mouth. especially when you are sitting in the emergency room waiting to get stitches from that 2 ft gash in your arm.
i use 3m super 77 - just do the smallest dusting. as resinhead says it will melt the foam if you put a lot on. but if you just do a really quick and super light spray, it will not affect the foam and it will be enough to hold the fiber in place.
The stringerless carbon rails are super responsive and they work magic in steep glassy perfect waves. Any sort of chop, backwash, flat spots, etc they are really hard to surf. How often do i surf perfect waves........almost never and my carbon railed board doesnt see much action. Check out Lemats boards - he has some super super clean looking carbon rail boards. I documented one i did here on sways a while back: http://www2.swaylocks.com/node/1028134
My experience with bamboo is opposite of carbon. Carbon is super responsive to the point of feeling jittery if you are not on your game. Bamboo seems to dampen the flex response making a very smooth ride.
[img]http://cdn.dickblick.com/items/237/09/23709-1011-1-3ww-l.jpg[/img]
According to a friend of mine, this is the stuff the model airplane builders use.
G-hopper, my experience with CF rails is different than yours, but then, I probably glassed the boards a little heavier (had a 6 oz., 2/3 deck CF/Kevlar hybrid cloth inlay, topped with 2 full layers of 4 oz e), so most likely that was a factor.
I think that the key for carbon rails is to not go too far from the neutral axis. That way when board flex, carbon is not stretch so much and it doesn’t take all load and it doesn’t spring back too hard. All is a balance and the main thing is the skin lam. In my construction i play with fiberglass direction to make more or less flexible skin, carbon is for improve dynamic durability. The guy i made the gun (big wave power surfer) says that’s what is magic is how he feel projection after turn and how he feel the board deform to stick to wave in choppy surf.
Personally what i found (small surf light surfer) is that when i pump my board it bounce and take lot of speed. I never experiment this before in my 20 years of surfing. No more problem in choppy surf. My carbon boards are flexible than my stringered boards. But i am just a garage shaper.
3M77 spray is what we use for RC plane models, directly on foam with no problems if you want.
Sorry for my frenglish.
lemat, thanks for the vote of confidence. I have found out lots of good and bad with CF rails. I still have a lot of CF tape left, and three blanks of 1# eps foam that I intend to build out with CF rails. I’m about to finish another in a few weeks, and you definitely don’t want to overflex them, but with the fancy woods that I have laminted to my current one, that will not be a problem. Build what you want, figure out if you like it, and move on.
ok after the cf rails are on and dry, how do you go about sanding them down before lamination?
[quote="$1"]
ok after the cf rails are on and dry, how do you go about sanding them down before lamination?
[/quote]
You shouldn't need to, but you can baste them prior to laminating over them to fill the area at the edges of the "cutlap." If you want to sand them, you should mask off anything you don't want black/gray dust to get into, because you'll have a hard time getting it out of the EPS.
lemat - what do you mean about keeping the carbon on the rails close to the 'neutral axis' and how to you achieve this?
Lemat, I was also wondering about the ‘neutral axis’? Apex? 4” or thinner tape that doesn’t wrap too high?
I just saw this video of Todd Proctor mentioning he uses uni-directional carbon on the rails. Anyone have an opinion on uni vs,3K, 12.5 X 12.5 tape?