hello. does anyone know how to make your own fins ? they are getting to expensive !

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markaru27 said..

hello. does anyone know how to make your own fins ? they are getting to expensive !

www.seabreeze.com.au/forums/Windsurfing/Gps/18cm-carbonstainless-weedy/
thanks too Nathan bowness,first run strait from the mould with 10mm sticking out from the back of the base ,with the foil slightly out of wak, JP 50 speed 37.3 2 sec 35.75sec and a 32.9 NM,
I have recently purchased a jp 50 speed ,I have refoiled all the fins and have them fitting properly in the box, hope to catch up with Nathon again at illawarra for another test run,

If you think you can get into fin making to save money I think you are mistaken, unless you have unlimited free time. I followed also Decrepit's posts (www.seabreeze.com.au/forums/Windsurfing/Gps/timbercarbon-fins/?page=1)and it is a very complex and time consuming process. Most people that work on fins do it for their passion and will to experiment, if money was a factor they would be better off buying a second hand fin.

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powersloshin said...
If you think you can get into fin making to save money I think you are mistaken, unless you have unlimited free time. I followed also Decrepit's posts (www.seabreeze.com.au/forums/Windsurfing/Gps/timbercarbon-fins/?page=1)and it is a very complex and time consuming process. Most people that work on fins do it for their passion and will to experiment, if money was a factor they would be better off buying a second hand fin.

powersloshin ill have to agree with you 90% but how do you buy a carbon fin to suit your sailing conditions, decrepit has been making fins for ever and a day and has a good understanding of resins and how humidity can effect a timber fin and knows how to deal with it, personally I wouldn't event attempt to make a timber fin and laminate it, I have a decrepit 26 weedy and its a work of art , if I tried to make that fin it would be very asymmetrical and probably unsailable
I have a post further down the page www.seabreeze.com.au/forums/Windsurfing/Gps/18cm-carbonstainless-weedy/ I have laminated carbon(vinylester) 6mm thick between two pieces of ply, wedged it between two pieces of stone granite and leave it clamped for a week, what you have is a perfectly flat blank and theres no reason why you couldn't use a cnc machine
all you need to do is sand two wedges one from the base to the tip and the other from the leading edge to the trailing edge and round off the foil and laminate , its that simple
you say you need unlimited time , ok so say your going to LG next year and want a 18cm 48deg carbon weedy,
you need say 3hrs to cut the ply and route 3mm either side and to fill with carbon and clamp
when you have 1hr foil one side , if you don't have enough time to laminate clamp it down to some flat melamine
and leave it
when you have a spare 1/2 hr cut some unicarbon and leave it
" " " " " 1hr dig out the cut carbon and laminate one side ,wait for it to cure , clamp it down and leave it , remembering one side is flat
when doing the other side you will need to foil and laminate the same day the leave it
what you will need is a mouse sander and a hacksaw blade, just sand the two triangles (or v's with the mouse sander)then hacksaw blade is essential too keep it all flat and strait and no bumps and too round the foil
the final tuneing is what takes the time ,but again its only in your spare time, it's very therapeutic making sure everything is strait and flat no bumps, if you need some help send a PM or maybe ill catch up at LG next year and the 3 of us can compare our handywork
what I forgot to mention is these fins are 80% carbon , most of the ply is sanded

thanks Keef, I admire your work and Decrepit's, but I am not into fin making yet, just too involving for me. Maybe I will start with some reboxing. I was just trying to explain to markaru that doing it to save money is naive.

well thanks for sharing your knowledge

I have to agree, the easiest way is to modify an old fin. Starting from scratch is sometimes necessary, but a lot more involved.

A mold would be the way to go, I keep thinking of making one, but so far all my fins have been different. If I can settle on the ideal design, then the hassle of making a mold would be worth it.

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decrepit said..

I have to agree, the easiest way is to modify an old fin. Starting from scratch is sometimes necessary, but a lot more involved.

A mold would be the way to go, I keep thinking of making one, but so far all my fins have been different. If I can settle on the ideal design, then the hassle of making a mold would be worth it.

decrepit , making a mold isn't a hassle it's easy as long as you have a good gelcoat, the 3 fins I molded I beefed up with spray putty refoiled and molded , after the mold I reshaped back to original so now have 6 fins , two 22cm,two 19 cm&two 17cm, im still working on them and eventually ill get it rite
if you have a mold say 24cm 40deg and want a 22cm, just lay the mold up and reshape down too a 22cm, if you have a 40deg mold and want a 45deg , just lay the mold up and fill the bottom of the base with plastic or something when you pull the fin from the mold you have a 40deg with only the center of the base , now you refoil and reshape and box at 45deg or vise versa
its also a good way to get rid of your bits & pieces

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powersloshin said..

thanks Keef, I admire your work and Decrepit's, but I am not into fin making yet, just too involving for me. Maybe I will start with some reboxing. I was just trying to explain to markaru that doing it to save money is naive.

powersloshin, don't get me wrong , I buy fins , i have a bunch of c3 venoms, slingshots & mfc, if they made a fin that suited my sailing i wouldn't be wasting my time making them, i would be putting my time into modifying a board , these board manufactures are like a bunch of browns cows , one company brings out a new feature and next thing all the other boards are the same, same as foot straps i decided to go back to the conventional straps last season only to find i had the heavy weebing used as an adjustment digging into the top of my foot, and they were sitting so high on the deck i kept tripping over them going into the jibe
im not into making stuff to save money, don't get me wrong these companies are making top quality stuff that's why i modify rather than start from scratch
back to fins take the 22cm 47deg carbon i made, if that fin was cnc cut from g10 it would weigh 1kg i can do it at 350gr with a stainless edge, i also made the mold so i can chop it down to smaller sizes and change the rake ,
here's another point, these companies are making carbon fins and not expecting them to be sailed in places like illawarra (shallow sandy bottoms) carbon is like the hb pencil you used at school very soft and wears fast, if sailing on sandy bottoms they become very serrated fast and your 40deg speed fin can look like a freeride fast
now for the guy out there that keeps red thumbing me, i have reported you to lorry, he assures me if you keep harassing my posts he will black ban you fast

You all know the Rake 30? fins,but who was the first who worked such a fin for speed.? Remember: Martin van Meurs
was the first who made a topspeed with 50 knots.The fin was upright and from Boogie.Thomas D?blin was the first
who used a 22cm Rake 30?fin in 100% carbon. Topspeed 50 knots.Now work all Rake 30.? Now to start to work fins
I think its easy, you can see and read all what you want. I started with the idea,worked a Prototyp in G10.Tested in
Strand Horst in Netherland.160km from my home.The first mould for a carbon fin in 22cm. Doubleasymm.fin.Mould with base. Only for 22cm fins. And the first fin made some years later 50 kots.Now for L?deritz 17cm 18cm.Have I a new
idea? Yes,she came from Thomas D?blin. Very simpl,work a asymm.profile and than cut out and the concaves
diagonal. I worked one and she is faster. Now I wait: L?DERITZ A long time.But a good feeling. If you have a good idea, work fins,and think carbon is always faster than G10. Wolfgang

wolfgang I have always admired your fins and thanks for that valuable informationa bout the 30deg rake , our sailing spot doesn't have anywhere the weed it had last year so we can get away with 40deg rake, theres a couple of questions I would like to ask

I have seen a fin of yours that had a concave at the leading edge on the base of the fin, and a concave down the trailing edge on the other side , can you explain how that works

also do you think the fin needs to be full cabon, my experience is a part of the base and foil sec can be foam core

also what are your views on vinylester opposed to epoxy, from experience I would say vinylester

also your views on the thickness of the fins with different rake's, I have found with a 22cm 30deg rake you can go quite thin 1/3 of the base down, where as with a 22cm45deg rake you can have the foil fuller and futher forward from 1/3 of the base down or am I on the wrong track

also can you explain how your cancaves work, wolfgang keep up the good work and ill cya in October on the speed strip

I go in 10minutes to Strand Horst in Netherland.I will answer on Monday. We have here in Germany a long weekend.
KEEF: www.designlessacher.eu Wolfgang

Keef this the English translation from lessacher website www.designlessacher.eu

While surfing, the Board runs diagonally to Lee through the water. The result, a positive pressure on the Leeward side is behind the Finn at 45 ?, wanders to the windward side,
where is vacuum. Jerky motion of the Board or sail
This roller on Luv moves around to the front, around the nose, and the rotation starts. Spin out.
A concave on Lee was the solution for many years for a direction.
Concave front on both sides do not work.
So, depending on the course, left or right fin.
They drive in both diagonal offset the concave
Directions spinout free.
Another advantage is created also by the shovel-like shape of the concave,
because it can absorb much greater lateral forces such as a fin in identical size without concave!

Why a cutout?
Cut out the water - air mixture, producing the Spinout, throws out sucked from the suction side of the Finn from the bottom of the Board, direct on the cutout back.

Why and when carbon?
Especially in the race area is demands more and more power of the material being fast always thinner and lighter profiles be developed.
Normal CSF (G10) shows boundaries in terms of stability as quickly and as the high-quality carbon fibre is then fiber (carbon) used.
Not only for surfers with more weight in the Raceeinsatz a must or plus!

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decrepit said..

I have to agree, the easiest way is to modify an old fin. Starting from scratch is sometimes necessary, but a lot more involved.

A mold would be the way to go, I keep thinking of making one, but so far all my fins have been different. If I can settle on the ideal design, then the hassle of making a mold would be worth it.

Couldn't agree more, I need different fins for different conditions. Getting an all-rounder would be ideal, but just when I think I'm getting close I find small flaws in the project that need rethinking.
I'm fairly sure that for the money that I'm spending experimenting with design I could go to an engineering workshop and ask them to make me and aluminium split mould.

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pepe47 said...

decrepit said..

I have to agree, the easiest way is to modify an old fin. Starting from scratch is sometimes necessary, but a lot more involved.

A mold would be the way to go, I keep thinking of making one, but so far all my fins have been different. If I can settle on the ideal design, then the hassle of making a mold would be worth it.

Couldn't agree more, I need different fins for different conditions. Getting an all-rounder would be ideal, but just when I think I'm getting close I find small flaws in the project that need rethinking.
I'm fairly sure that for the money that I'm spending experimenting with design I could go to an engineering workshop and ask them to make me and aluminium split mould.

I have made a few modifications the the fins I molded, so about to change the molds , not sure how you would do that with aluminum, if you use the carbon dust from when you foiled your fins with silica(aerosol) for the tooling gel I cant see why you would need aluminum
out of interest how would you engineer a split mold

I've settled on a design but now have to make another fin to have a mould base. The idea is to have one mould for several sizes of fins ranging from 35 cms down to whatever size suits. Make one and cut the fin to size. However, getting the profile and shape perfect on the large fin is daunting to say the least.
Most carbon fin makers use ally because the moulds will stand up to wear and tear better than the polyester/gelcoat moulds, which will chip after half a dozen fins have come out of them. I've been using the fibreglass fin box moulds and have to constantly repair the damage I inflict on them through regular use, and have therefore gone to an aluminium split mould. I've reboxed around 20 fins with the ally mould and the boxes remain the same as when it was made with no imperfections.
The split moulds can be made by a cad design programmed into a cnc machine then cut from two billets of aluminium. You can program it to drill and tap the holes for clamping without removing it from the machine as well. Get the design right and you've got yourself a (near) bullet proof mould that will last. Weighing up the cost is the factor that determines whether it will pay off or not. I may be lazy but I'm growing tired of having the back yard covered in fibreglass dust. And she who must be obeyed has mentioned on the odd occasion the the washing has been itchy (buggered if I know why).

As for the question of fixing an aluminium mould. I first had this mould made and the box radius was 3mm which I found needed sanding to make it fit. I then took it back to the engineering place and got them to mill 3mm off the face (where the moulds meet) and recut the box at 5mm radius. To the tune of another $300.00, but for the sake of convenience I was prepared to pay. Quite an expensive project so far but I'd rather be reboxing fins instead of making moulds.

This is the design that I've settled on but keeping the cut-out as the fins get larger has me stumped. If I cut the fin to size and retain the cut-out the underside of the cut-out will be up to 2mm on the larger ones. I'm not completely sure if this will effect the cut-outs ability to shed air, making it cavitate and spin out. I have seen the jp fins cuts and they do have a couple of mils width which doesn't appear to effect their performance.
I've probably spent about $500.00 on supplies so far and that's without taking into account the countless hours spent developing the shallow water weed fin. I'm also guily of a fair bit of plagiarism as the more research I did into the way the fin performed the more it looked like Tim Hemer's "Tomahawk". I'm going to go with co-incidental on that one.

Hey Pepe How can I do a Homer Saliva Dripping from My Mouth emoticon?

Hey Hards, if I can get the mould happening you'd be most welcome to a couple in appreciation of what you've done for GPSTC.

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pepe47 said..

Hey Hards, if I can get the mould happening you'd be most welcome to a couple in appreciation of what you've done for GPSTC.

You are extremely generous my dear friend, we'll speak personally about it, but upon reading your post I became cured of my erectile dysfunction disorder, weird hey, women cant do it any more but windsurfing gear can HOW EMBARRASSMENT

no wonder your fin bases look so good

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markaru27 said..

hello. does anyone know how to make your own fins ? they are getting to expensive !

Thanks Keef, and if we extend the same amount of effort into making the fin moulds themselves keeping the foil and shape true then hopefully the fins will turn out well also. So for another $1200.00 I can have the cad design programmed into the cnc machine and have the moulds done.
So, back to the original question, if you're prepared to spend around $2300.00 getting set up, I guess you can make the fins slightly cheaper than the fin manufacturers, but not by much and certainly not of the same quality as theirs. Keeping in mind that this design is only one sort of fin and most manufacturers will have more than one fin design.
You can, of course, buy second hand fins which will do the same job and if they're slightly damaged the fin can be tidied up with some wet and dry if you don't alter the profile.

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pepe47 said..

I've settled on a design but now have to make another fin to have a mould base. The idea is to have one mould for several sizes of fins ranging from 35 cms down to whatever size suits. Make one and cut the fin to size. However, getting the profile and shape perfect on the large fin is daunting to say the least.
Most carbon fin makers use ally because the moulds will stand up to wear and tear better than the polyester/gelcoat moulds, which will chip after half a dozen fins have come out of them. I've been using the fibreglass fin box moulds and have to constantly repair the damage I inflict on them through regular use, and have therefore gone to an aluminium split mould. I've reboxed around 20 fins with the ally mould and the boxes remain the same as when it was made with no imperfections.
The split moulds can be made by a cad design programmed into a cnc machine then cut from two billets of aluminium. You can program it to drill and tap the holes for clamping without removing it from the machine as well. Get the design right and you've got yourself a (near) bullet proof mould that will last. Weighing up the cost is the factor that determines whether it will pay off or not. I may be lazy but I'm growing tired of having the back yard covered in fibreglass dust. And she who must be obeyed has mentioned on the odd occasion the the washing has been itchy (buggered if I know why).

Hi Pepe,
To help with the Mold chipping problem, try adding calcite to your gelcoat brew.
Calcite is used in Pottery so available from Pottery Supply outfits. Hard stuff. Somewhere up there like silica for hardness.
I mix 128% currently (started at 83% and using more all the time) to the resin mix for the gelcoat.
Good stuff, makes the mold face way more durable.
I use Nuplex R180 resin.
Watch some of the fancy resins, they are more likely to stick up.
For CAD molds use Phenolic Resin instead of Alu. Less expensive, much easier on tooling and so far I've done probably 50 or 60 fins out of one of my molds and still going strong. I polish with release wax and then spray with PVA to make real sure of no stick ups.
I like the self made fins, MUCH cheaper and I can plough the bottom happily knowing that for under $50 I can replace the plough shear.
They are not expensive because you don't need much carbon to get the flex correct.

Clever bunch, you kiwis. The usual gelcoat is chalky to say the least but adding calcite is a great idea. The chips that used to appear in the gelcoat were usually around unseen air bubbles and were not found until it was too late. Trying to fix the mould was a nightmare. Sanding the fault in the mould without taking too much around the divot really was hard, even using a sanding block.
I've been painting the pva release agent on to the mould with a synthetic brush and leaving it to dry in the sun.

Of course there's always my Thai cnc machine. Bought two pieces of phenolic sheet from the states, 6.5mm and 1mm. Laminated them with some carbon, not so much for stiffness, more for making the thickness required to have a chord ratio of 8%.

Keeping the profile, for those who have a millionty hours on their hands.
And a large supply of sanding belts!

Finally, after about 10 hrs straight. Now to box the fin...How we going for saving money!
Hobby, possibly. More of an obsession.

Looken great Pepe its the ginger beer thats making it into a obsession keep up the good work and have one for me

Great work Pepe, I feel tired just looking at the finish and all those itchy hours of work.

I have a bit of work to finetune my fins but I am making some progress on "quick" moulds. Instead of gelcoat/glass-epoxy/benchtop offcut;) I tried just casting the moulds with a thick benchtop backing for thermal mass and rigity for vacuum clamping. It worked just as well as the expensive Ciba aluminium tooling gelcoats I have used in the past at a fraction of the cost. Since the cast aluminium/epoxy body is 7 or 8mm thick you dont get the chipping from trapping air in the layup. Also the aluminium sinks(increasing the mould face durability) and air bubbles rise to the surface and vent. No cutting and laying glass, the only thing I did do was key the benchtop and chamfer the edges for improved adhesion. The mould probably cost $80, the main cost is the aluminium powder.


Casting the first half.


Fitting the backing block.


Keyed backing block


Second half finished.


Mould surface.

Only 2 fins out of the mould so far and they dropped out, only wax - no pva.

Hey Kimba, are you going to do a step by step on Whitelion windsurfing. Makes it easy to follow your mould making design. I like the idea of aluminium powder. And $80.00 sounds better than $1200!