Making Surfboard carbon fiber fins

General Composites Discussions Composites Talk
#1

Hello,

I am new in this site, but I am really into composites, I knew about them a while ago but now that I have some Mechanical Engineering classes in college, I got to learn a lot more about them and I am currently trying to build/make my first Carbon fiber product.

I am trying to make some Carbon Fiber surfboard fins, talking to some professors, I had two options on how to make them: using EPS (expanded polystyrene) as a core foam, or balsa wood as a core and then covering that core with the carbon fiber and the epoxy.

I am trying to make fins just like the ones I posted on the picture, I think the ones I have are made of fiber glass with a very thin foam core. I am not sure on the process on how to make my own fins that’s why I am asking. All suggestion and comments are more than welcome.

Thanks

Al

#2

I see Lantor Soric in there.

#3

Nice, I was trying to find out what they put inside those fins. But would you recommend me using Lantor soric as the core for my carbon fiber fins?

#4

I was actually just in a factory last week that was making these exact same style fins. Wonder if it is the same manufacturer or not.

#5

I talked to Lantor (manufacturer of Soric) the other day, and these cores are basicly in just for the looks, and a bit of weight reduction.

You can spray the Soric another colour, for some wacky effects.

#6

Hojo,

They were probably the same fins, what was the name of the producer?

#7

Herman, that’s what I thought, they put the Soric inside just for look, and even in the weight there is not that big of a difference… What I was reading about Soric is that is used because it has a very small resin absorption, since fins are so small there difference in weight would be almost the same.

I am still trying to make my carbon fiber fins, I am not planning on using the Soric as a core, but I still don’t know what kind of core would be the best for carbon fiber fins. Suggestions??

#8

Some sort of compressible core. Can be a low density foam, or Soric, or Coremat Xm

#9

Herman,

Low density foam such as EPS? I wouldn’t use the Lantor producs since they are kind of expensive and hard to find.
Also I was thinking on Balsa Wood… What do you think?

#10

Are you going to bulk produce, or just for personal use? I would think the 1sq.ft. of Soric needed would be accessible, and cheap, you could even likely pay shipping to request a sample.

#11

This is a personal project. How can I request a sample? Or any websites that sell Soric, please.

#12

http://www.ebay.com/itm/LANTOR-SF1003-SORIC-SF-3MM-50-INCH-WHITE-HONEYCOMB-BOAT-CORE-MATERIAL-YARDS-/200658509296?pt=Boat_Parts_Accessories_Gear&hash=item2eb82dddf0&vxp=mtr

~$26.00 shipped for one linear yard. You should have enough for a ton of fins, or testing multiple options.

#13

Unsure the factory name, they do boards for several companies.

#14

If I use Soric, do I have to do Vacuum Resin infusion? Or I can just use it as the core and then cover it with the Carbon fiber cloth

#15

No, you don’t but you would be wasting some of the properties of the product, so you could as well thoroughly wet out and use any core material, like Lantor Coremat and save some money.

#16

I ordered the Soric XF 2mm, I am going to try to vacuum infusion it. I will post my fins once I have them ready.

#17

I make these regularily to save money, I kite surf in a shallow reef and bust a lot of fins. at $100/ set It’s pretty ridiculous) I also build a lot of surfboards and have tons of scrap bits kicking around which is nice for fin making.

The easiest way to make a small one off quantity of these is to take a chunk of scrap 1/4" HD foam core, (divinycell, core cell, soric/whatever.)
and hand sand your foil profile.
It’s pretty easy to sand and get a good smooth consistent foil profile.

Make the tabs for the fin boxes a little thinner than necessary.

The tabs for the fin box make them just a bit narrower than the rest of the body.
Then just lay up glass over the core, use oversized glass both sides and trim when done.

USE AT MINIMUM 32oz total of glass PER SIDE or it WILL break VERY easily. More for carbon, as it is more brittle and no stronger.

Once completed your tabs should be LOOSE in the finbox. cover the fin box in GOOD mold release (Loctite frekote)

Cast to the desired fin cant angle by stabilizing the fin in the box with plasticine and filling the fin box with a mixture of epoxy and milled glass…the harder the better as the set screws will chew into anything that is soft.

If you have a fin shape and cant you really like, mold making and infusion would be worthwhile for additional quantities. But if it’s just one set you need to make, you’re gunna basically build em twice with a mold.