anyone had a crack at making some fins? Would be a cheap way to try a big rudder fin or something.
was thinking of laying up 30 x 6oz to about 7mm thick in fibreglass then cutting out some fins then sanding. Other way would be do it out of wood and clear coat with poly.

Yes, it's not cheap, it's not quick and it's not easy, and when you consider the alternative, is going to Dion, Shapers or Surfblanks and buying a well made and proven fin design for $60 to $75, making your own makes no real sense.

Yeah good point. Time would be better spent surfing.

I make all my own fins so it's certainly possible. I've enjoyed experimenting with a lot of different sizes and shapes, to do the same by buying them would have cost a heap and I simply wouldn't have done it.

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saltyheaven said..

I make all my own fins so it's certainly possible. I've enjoyed experimenting with a lot of different sizes and shapes, to do the same by buying them would have cost a heap and I simply wouldn't have done it.

could you put up the construction method please ...it looks like glass over ply /wood

WOW, They look sweet. So how did you do the centre fin? just glass over ply?

Steve

If you're going down the glass over ply road, try to ensure that the ply goes all the way through to the mounting points.

At least 2 people here, Ted and Vanders I think, have delaminated ply fins that were made with the ply stopping at the point where the fin enters the box.

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obct said..
If you're going down the glass over ply road, try to ensure that the ply goes all the way through to the mounting points.

At least 2 people here, Ted and Vanders I think, have delaminated ply fins that were made with the ply stopping at the point where the fin enters the box.

I've got to pull you upon your post Obct.

Vanders who? Vanders dose not surf.

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obct said..
Yes, it's not cheap, it's not quick and it's not easy, and when you consider the alternative, is going to Dion, Shapers or Surfblanks and buying a well made and proven fin design for $60 to $75, making your own makes no real sense.

I tried once and have to Agree with obct. Pain in the arse and hard to get as good as the store bought ones.

Easier to buy them.

Second hand on eBay or GT is a great way to try different fins. Don't like them just sell them on and you don't lose much.

PM Roy Stuart

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Cobra said..
PM Roy Stuart

All fair enough, to each their own. I agree, if there is no interest or enjoyment in the making process and whatever fin is desired is available it is certainly easier to just go and buy one. For anyone interested in having a go at making their own I can share the following:

Rail fins I just do from a glass panel. I recently did two pairs of unusual sidebites (the bonzerish ones you see in the photo above and some tiny tiny little single tab ones) for a material cost of something around $10 and a total time of about an hour. Lay up the panel, cut out the fins, grind the foil, finish sand and wetrub. Easy and quick, not terribly pleasant grinding glass.

The centre box fins I make out of glassed timber. Yes, it is indeed a bit more of a process and involves a bit of trial and error to get a method that works, and experience to end up with a decent result. I've come up with something that flows pretty well for me, they take about an hour of total time each (not continuous) if I make two at once. The material cost is negligable. I have everything to hand which helps and I've been making things from wood and glass for a long time, however I don't use any fancy tools for fins. Maybe a first go for someone else might take many times as long, that's ok, it will get quicker each time.


(Photo's below...)
. Shape and foil the timber, allow for the glass thickness, ensure the part that will go into the box is thin enough.
. Glass with two layers of 6oz. I wrap the glass over the leading edge in one piece per layer, cut a slit towards the tip where the leading edge radius is too sharp for the glass to bend around, there are some rovings layed along the leading edge from just before where the slit starts to the tip, under the glass.
. Brush or roll on two filler coats.
. Cut the final outline and sand to final shape.
. The base mold is a few bits of wood covered in packing tape, close the bottom off with masking tape. Put a bit of resin in the mold, push the fin in, fill to the top. Reinforce the tab for the screw with some glass fibres, wet them out and put them alongside the fin extending into what will become the tab. (easiest when inserting the fin into the mold.)
. Shape the base and tidy up where the fin exits, drill the hole for the finscrew and another to take the pin.
. Surf!

The fin in the last picture is a different blade construction that I was playing with to try to get the flex how I wanted it. The picture is there to show a fin in the base mold.


I hope this helps someone or is at least interesting. Somehow I don't think the fin manufacturers need to worry about a rash of DIY finmakers.

Oh, for a big old 'rudder fin' to play with. I'd probably forego the glass and just go with plain timber, sealed with anything and set into the base mold in the same way. I've done a few this way, shapes without sweep lend themselves to it - elliptical fins, D-fins etc...

nice & thanx for sharing

Very cool. I got to give that a go. Can you get much flex in the tip of that big ass fin?
just wondering......how thick is the wood that you start with? Most fins are about 6mm thick at the thickest part. 2 layers of glass and 2 filler coats would add 2mm per side?

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OlSteve said..
.....how thick is the wood that you start with? Most fins are about 6mm thick at the thickest part. 2 layers of glass and 2 filler coats would add 2mm per side?

Maybe you have some unusual fins? I would have said 6mm is in the ballpark (still a bit thin) for thruster sized and smaller fins. 9.5mm (3/8") is far more typical for a larger box fin, some are thicker still and actually step out just above the box.
A layer of 6oz with a good resin ratio is more like 0.25mm. Allowing 1mm per side for two 6oz layers with filler is plenty. For a standard box fin with a 9.5mm base that would mean starting with 7.5mm timber.

These fins are naturally quite stiff despite their extreme light weight. Getting a controlled flex into them takes a bit of a different approach and I'm still playing with that. Try a basic one first.

www.korduroy.tv/shows/surf-sufficient/how-to-foil-a-longboard-fin/

My favourite board has the swivel fin set up. It's a 6'8" Len Dibben thruster, and I managed to break a few fins in the first year or so. Particularly the side ones. I bought his last remaining couple of sets as he told me he had been unable to get any more.
I've continued to break them and have been unable to buy new ones so resorted to try to make my own replacements. After a fair bit of R & D I've been able to successfully form some using 12mm Australian Oak.
The problem with the original swivel fins is that they break when impacted from the side.
So far I've only had to make the outside ones, but I've recently broken the centre one. I have one last centre fin so I'm about to make some oak spares to compliment the others.
The 12mm oak works well, and suits my very basic manufacturing set up. The fin socket in the board is 11.5mm wide, and there is enough thickness to create the internal flat angle to the side fins, and the external foil shape. I have been using linseed oil as a finish particularly so I can get it down into the fixing hole. The first set I used for about 3 months, then took them out to re oil them, then continued to use them for another 3 months. I've taken them out again to recoat and am currently using set no 2. The original set still look good.
I'm currently using 95mm fins, but have just made two sets of 115mm ones which I am about to try.
If anyone is looking for replacement swivel fins I am happy to make sets up to order.