Hi lads, I had a look through the archives but cant seem to find the answer.
Basically I’m looking to eventually make my own fins for a twinny that is going to be glassed soon. i have a few basic ideas of how to go about it.
Idea 1. just use wood, cut the shape, shape the outside surface, keep the inside as straight as possible. Then glass over (epoxy)?
Idea 2. Make fins from pure epoxy, i.e. build a rectangular “bathtub” of predetermined depth, fill with epoxy up to specific depth to regulate the foil thickness. then cut out the foil and shape the outside. Cover in glass? Possibly?
Idea 3. Layer a number of layers of 6oz glass (20, 28.36?), saturate with epoxy, prob. layer by layer. press between two wooden planks to ensure tight cohesion between layers of glass, cut out and shape as normal.
Now i’ve no idea if any of these methods work, will work or have ever been used by others or just plain stupid.
So can anyone out there point me into right direction?
Quick answer? Don’t use the solid epoxy method you’ve described. Either make a wooden foil and glass it, or make a ‘blank’ from multiple layers of glass. I’d use 10 oz instead of 6. I’ve made regular FU box type fins before. On a flat surface I put down a sheet of window glass, then a sheet of wax paper. Lay up the desired # of glass/resin layers. Then, another sheet of wax paper, another sheet of window glass, followed by a real flat piece of cabinet grade plywood, then a cinderblock for dead weight.
The window glass gives you a dead flat surface, and the wax paper won’t stick to the resin.
Maybe it’s just me, and G.L. doesn’t pay me for this, and maybe it’s just RR epoxy being such dang good glue, but I’v had sticking issues w/wax paper and plain alm. foil, but I’ve been using Reynolds "non-stick’ foil, and I’ve had not a problem at all… Just stocked up on three rolls (Happened to be 30% off! Stoke!)
The easiest way is to take nice piece of marine plywood (African Mahogany is a grand choice) that has 6 to 9 layers of wood and is about 3/8" of an inch thick and either foil one side or both depending on whether you want asymmetrical or symmetrical foils. After you get the wood foiled just laminate a couple layers of 4oz glass with epoxy like the fins are little surfboards and then glass them on the board with roving and football shaped glass patches, next fine sand everything out and shot a fill coat over it all.
The wood will look grand and do the job just fine.
Another approach is to lay up 30 or so layers of 6oz cloth in a fin panel and cut the templates out. Then foil the fins and glass them on. This would be more work than the wood fins though.
Definitely learn how to search. There is so much good stuff packed away into the swaylock ether. I searched and read for literally weeks at night after work before I made my first compsand.
Start with plywood so you don’t waste resin and cloth. The bamboo guy’s had some panels for an okay price a week or so ago, so I picked up a few pieces to see what it was like. I had not messed with bamboo before. I maximized the fin quantity from the panel on the ones below. Some would run the bamboo’s bonded length along the longest dimension of the fin, but we’re garage tinkers, so we can do what we want.
Just looking at your pic and I noiticed that you alligned the grain straight up… Make sure to put plenty of glass on when you are done foiling otherwise the tips of those fin might flex right off. There is a post in the surfermag forum discussing fiber angle… just read the statement made by Bill Barnfield (Posted by ProBox-Larry). http://forum.surfermag.com/forum/showflat.php?Cat=0&Number=1470118&page=4&fpart=3&vc=1 Look about 2/3 down the page to find the Barnfield comment (under probox-larry’s username). Tombloke and probox-larry have some interesting pics and diagrams on there.
Throw some of that carbon cloth sitting in the background of that photo on the tips and that will prob make it plenty strong, I wish I had some of that stuff sitting around.
I am currently making some glassed on fins for my twin-fin stubby using plywood. Shaping these were pretty easy. The polisher/sander that I used really made it go fast.
another thing that would be great to do is use what is known as Starboard/Seaboard. it is a very light yet extremely strong kind of fiberglass plastic used in boat building…i buy 1/4in think, draw a design and use a badn saw to cut it out then all i must do is round everythign off and like magic they work
Yes! Same idea as SammyA–i lived at and surfed Rocky Rights from '65- '-68, when Monster Rock was always in the line up, so we made a disposable fin system, wedged into a fin box, that allowed the fin to knock loose, and float–All out of plywood and glass–What we found out, was that with a simple , plywood fin, you had all of the cheapest, most workable materials at hand, and you could experiment. It was only when you found a fin that worked really well, that we would laminate up full glass mockups-(Not a lot of money back then , and FiberGlass Hawaii was a long drive from Country)–Shape whatever you want, out of wood or high density foam, just resin it, and see if it works --Then go into a better product–My 2 cents–mac
Greenlight surf supply has probox and longboard fin bamboo layouts that are already fit to the width of the box. All u do is make the template. Cut out foil and glass. Also read the archives thread started by Probox and greenlight they go over step by step how to do it. That’s just one option.
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