molding fins topic

[some-guy]

Ok, i am new to this website and i have been absalotely cringing at some of the methods that people have been suggesting to mold fins in these forums.

To start off, you guys are making it out like it is some massive process that just isn’t worth doing. Secondly, people are using some wierd materials that spell bad news from the start.

So, if you have ever thought of doing this, FORGET about the following things:

• pouring resin into a mold and expecting something good to pop out. It doesn’t work like that

• RTV Silicone, latex, rubber, or anything along those lines. It’s just not strong enough. 

• Plaster. why use it??

• Building some kind of box around the plug so that you can pour something into it. 

• Using heavy objects to hold the two part mold togethor. 

• Expecting there to be no sanding or cutting whatso-ever when the fin pops out. 

 

So if you want to do it, you do it with a simple two part fibreglass mold bolted togethor with layred fibreglass to make the fin. Here are the processes:

 

Making the mold

Coat your plug with 5 layres of release wax, buffing it up to a perfect shine each time it sets. 

modeling clay the edges of the fin to make sure no resin gets undernieth it. (up to the half way point) you don’t need to do this if you are making a side fin

Coat your entire fin with gelcoat to ensure that smooth mirror glaze

when the gelcoat goes tacky, mix a ton of your chopped up offcuts into your resin and paste it on the gelcoat. Go all the way round making sure you leave enough room for the drill holes.

Let it go off completely. 

Pride it off your work surfaced (waxed aswell, just with a candle to save the good stuff) and flip her over. 

However tempting it is, don’t remove the fin. 

Remove all of the clay and start again with your release agent, obviously doing the mold aswell.

Then another gelcoat and a hell of a lot more chopped strand.

When it is solid, pride the two molds apart and drill your holes for the screws, usually abot 10 for a big single fin. 

remove your perfectly good fin. If you did 5 coats of release wax on each side, it should be intact

At this stage, i bolt the two halves togethor and if you are using wingnuts, glass them on to one side of the mold. This means that you can use your electric drill when you want to compress your two molds togethor (works much better than the heaviest object in your workshop, and the pressure is even)

 

So now you have your simple two-part mold, ready for use. Whenever i do this process, i always make at least 5 molds at a time to make it worth doing.

Now you simply have to make your fins. so get laminating

I am so sorry i don’t have a working camera at the moment, as soon as i get one i will post some pictures up. I would really like to see your pics of the goodies that pop out of these molds. 

 

Never be scared of trying and failing. Be scared of not trying and regretting 

[Florian_R]

thanks for the explanations. but what next? I assume you cut some glass, put it in the mould and pour resin in it. but how do you actually laminate the fin avoiding air bubbles? How do you make shure the moulds are completely filled with resin and glass once you close them and clamp them together?  

[fins]

welcome to swaylocks !

 

and now , when you get your camera , DEFINATELY post up some photos please , 'some guy'

 

  you will have lots of people interested !

 

  a first post on fin moulding , complete with step by step photos ,

 

  would be as well received as a good fin foiling video would have been ,

by another person who promised .  We are still waiting on THAT one ...it has been MONTHS , now !

 

 [make sure you deliver the goods , therefore ...we have reams of people who have come on here over the years , asked for / demanded advice or taken advice , only to never re-appear or show us any results . ]

 

  I'll eagerly await your photos

 

  cheers

 

  fin tinkerer ben

[some-guy]

i am glad to see that this topic is still sparking people’s interest. I will put some photos up soon.

Sorry i didn’t put up an explanation up of making the fin because i thought it was fairly obvious when i said “get laminating”.

I would like to ban the word “pour” 

get this idea of pouring resin out of your head, it doesn’t work like concrete

cut your cloth, release wax the molds, gelcoat first then laminate each layre 1 by 1 (or 2) with your sponge and spreader card. Don’t use much catalist. The mold is capable of compressing fibreglass with a lot of force if you glass the wingnuts on and clamp it shut with a drill, (but not if you use lots of catalist) so about 50 layres of 6oz is about right for a big ol single fin. If your a cheap skate, use chopped strand in the middle, not that i do that. When it pops out, run it through your bandsaw to trim off the excess, sand (not foil the edges, and drill your holes with your pillar drill. -don’t attempt to use a handheld drill, it has to be straight or the screw won’t bite the plate right when you want to surf it. i’v made that mistake before. 

This has to be the easiest method of making a fin. I have tried foiling and it is itchy and frustrating. Give it a try and let me know what you think.

 

time is love

 

[Florian_R]

sounds interesting, may give it a try. But I think people tend to make fins by foiling them is because you can try a lot of different shapes easily. With your method you need a mold for each shape. I try to get the best of both worlds by foiling wooden fins, glass them and using a mold to create fin tabs (FCS or Future). different story, may post some pics of my fin adventures soon. but let’s see your’s first:)

 

 

 

[NuclearFishin]

Excellent stuff mate

Bring on the pics - threads like this are what Swaylocks is all about !

[LeeD]

kinda like blank molding, I"d say, or fairings for cars and motocycles....

Any fins made yet?  Some guys are getting $1,200 for ONE fin, 70cm long, for windsurfing Formula boards.

You interested?

[BarrySnyder]

 Let me tell you of my experience with molded fins. When I was a fin and hotcoat guy,(twenty-plus years ago) I was working for Gary Linden. He tried this idea of making some fin molds. Sounds similar to the ones you described. He made three molds. Two for the side fins and one for the center. His idea was to take the left-over glass from laminating boards and use it to make fins. Sounds good in theory right? He paid this guy to semi-laminate the fin molds and put them together to set.

Being the guy who actually installed those fins, I was shocked to see that the fins had tons of air bubbles. I mean a lot. I realized that fiberglass and resin was hard to work with inside a mold and control the laminating process UN-seen inside the molds.

Needless to say, we went back to hand foiling our fins.

The great thing about laying up fin panels is that you can actually see the cloth and resin. I use a roller to lay up multiple layers.

Yes it is more work to cut out and foil fins. But like somebody else said, you can easily make many different shapes and sizes. And colors.

I’m not saying your process does not work, I hope it does. I would love to see them. Maybe the birth of a new fin company eh? Post some pics of the finished product. (And the whole process if you can)

Curtis Hesselgrave is hands down the best fin foiler I have ever known!

That;s my two cents worth.

Barry Snyder/Fin Maker

 

[martymo]

Sounds like half way to RTM. RTM aint that difficult. Lay in dry cloth and core (Lantor Soric or similar). Use a low viscosity, easy to obtain Vacuum Infusion / VARTM resin and pressure the resin in through an inlet port and allow another port as an exhaust or vacuum line, after some fettling…no bubbles.  We used to make small military aerospace housings this way.  

Top tip: cheapest way to pressurise resin for injection is use air pressure. Pumps are trouble for garage composites dudes…and some full time composites manufacturers!

[martymo]

…but as Barry alluded to, why would a home board builder want to go to the expense, complexity and lack of adaptability of moulded fins.

[thrailkill]

In 1958/59 Velzy&Jacobs came out with a molded hollow glass fin.      They had problems with tiny pin air passages allowing water to penetrate into the fins.    You’d see boards sticking out the back of cars, (pre roof racks) with water sloshing around inside the fins, as they drove down the road.

[chrisp]

Welcome back Bill T.

[alma_quilhas]

hi guys! so nice to see a post like this one. I’m from Brazil and we have a handmade fin factory but we are starting some tests with the RTM Light Thechnology. 

some pics bellow.

the red fin from left is a handmade prototype building with 100% 6oz fiberglass and the others fins are the first test with the RTM L.

[satch]

Hey Alma,

those fins look great. Would you be willing to share a few more pictures. Perhaps of the two mold halves and the RTM equipment.

Thanks!