pressing a board this summer

[vapor]

I’m going to be using 20 ounce tri glass for the top layer,but am considering carbon for the first layer. what weight of carbon have people been using if they’ve been pressing with carbon?

[Darrick]

You definitely should consider using the same material above and below the core. Not doing that will cause problems with base flatness. Have you made a board before? If not, maybe stick with cheaper materials for your first couple until you get a few under your belt. My two cents. Good luck!

[vapor]

G3 has been going it on some of their boards for awhile. have both carbon and glass boards right now and am going for something in between in feel. Anybody else have problems mixing materials and can give me reasons ?

[Scooby2]

Hey Vapor, it’s the different shrink rate of a composite in a heated cure cycle that can cause trouble. if the base shrinks more than the deck you get a concave base which is a problem. If you go a bit convex it’s no real issue as long as you are careful not to go through the middle of the base when finishing.

Different cure temps above and below the board can contribute to this too. There are a lot of variables and your base is of course more affected in the tip and tail areas where it is thin. There are pages and pages of this info in skibuilders.com

Your first boards can be sort of a shot in the dark. If you are thinking about adding carbon to lighten your board you would want to significantly reduce the amount of glass and resin used. Like, maybe use two 4 oz layers of S glass one at 0 and 90 and the other at 45 degrees and a 2 to 4 ounce unidirectional carbon layer top and bottom. Its fun to use higher grade materials in your own build, the cost is nominal compared to the rest of the picture. I’m currently using Carbon Textreme at $45 per board and adding patches of 2oz. innegra at maybe an additional $15-25 per board.

Or if you are just looking to get a real stiff board add a 4 inch wide strip of Unidirectional carbon to the top and bottom of each board half with your 20 oz glass and standard core profile. Look at Soller composites for uni carbon at great prices. S2 glass from fiberglasssupply.com.

Core thickness has a huge impact on flex, roughly twice the thickness yields about 4 times the stiffness, so a mm or two makes a noticeable difference. Torsion is another issue with your fabric, basically diagonal fibers and thicker cores increase torsional stiffness, not much an issue if you live in BC, which I think you do.

[Scooby2]

The 20 ounce triax E glass is good for all conditions (bad conditions) boards because is relatively stretchy and makes a durable board that can absorb a lot of energy (think resort hardback) and bend a lot without breaking. Carbon’s strength is adding stiffness with much less weight in the fiber and the resin, but it is more twitchy on ice and doesn’t tolerate real deep bending as well as e glass. S2 is just a higher strength fiberglass so use can use a little less fiber and therefore resin and get a similar but in my opinion better result.

Fiberglass supply has a unidirectional s2 glass at 6.5 ounces, but three layers of that is almost the same as your 20oz. The unidirectional performs only slightly better on the base than woven fabric, but in compression on the deck, it is generally accepted that woven fabric only has about 80% of the strength of unidirectional fibers (the weave bends allow fractures to start earlier). Also uni uses a bit less resin so it is a tad lighter overall

(more fun writing about layups than fixing sprinklers in the yard)

[vapor]

Thanks Scooby. As always we can count on you for answers concerning board layup and your right about being more fun than digging trenches for a sprinkler system

[vapor]

Who said you cant mix carbon and glass, light damp and fun to make.

[InTheMountains]

vapor wrote:

That looks like the Keyhole

[vapor]

Right you are!! Fun july mission with some rossi/nelson friends