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Selfmade fiberglass fins

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
landshark sa

landshark sa

Well-Known Member
Feb 15, 2011
353
183
83
Hi there !
I'm interested in starting my own fiberglass fins project and have a question (and will probably have a lot more in the coming weeks/months !) :
Do you guys have some feedback on long-term (multiple years...) durability of homemade fins ? Like how are they aging comparing to fins of known brands ?

I'm no expert but I'll chime in anyway...

As with off-the-shelf fins, I have self made fins which broke after very little use and I have fins I made quite a few years ago that are still going strong.

Unfortunately I don't have any empirical stats, i.e. fin A lasted 10000 kick cycles compared fin B which lasted 8000, but for sure it's possible to build diy fins that last as long and work as well as known brands, the trick is to find that perfect match between performance and durability - something that takes A LOT of reading, learning, experimentation and testing.

I forgot my other question : I see epoxy is the most recommended resin but does someone have more detail about which epoxy to use ? Because on the website I went on, there is a multitude of choices (standard, surf, high performance, flexible,...)

There are so many different types of resins, each with different properties, it's actually a huge field in itself. If you do decide to go down the rabbit hole of composite development, it will be best to use the resin technical specification sheet to do comparisons between them in order to find what will work the best for your design and for that you will have to know how metrics such as tensile modulus and strength, flexural modulus and strength; interlaminar stresses; elongation etc impact your design.

Probably the most import thing is, you want match your resin to your reinforcement - for example carbon fibre can handle a lot less elongation than fibreglass so you want to resin to be able to work well within the parameters of your material.

Some other things that I can think of off the bat that may not initially be obvious:

As its dive fins which could possibly spend a lot of time outside you want UV Stable resin.

Match the viscosity of the resin with the application method - i.e. for infusion you want a lower viscosity as the resin has to run through the whole part.

Consider your work environment. In a diy setup where one doesn't have a perfect temperature and humidity controlled lab to work in you may want to compromise on ultimate strength vs flexibility handling the resin.

If you are beginning, look for a resin that has a longer pot life. Although these type of resins usually take longer to cure and possibly require post curing they will give you more time to figure things out and optimise on the fly like routing up infusion lines etc and will provide more flexibility to guard against uncontrolled exothermic reactions.
 
daweasel

daweasel

Member
May 22, 2017
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@landshark sa thank you very much for all those details !
It seems I will have to make quite many try to get a pair of fins that works for me, so let's get working !
 
landshark sa

landshark sa

Well-Known Member
Feb 15, 2011
353
183
83
Hello! I am currently making carbon fiber/fiberglass fins for a project at school. Do you guys know where to get the rubber rails for the side of the fins? In addition, any information you guys can give about tapering the fin would be greatly appreciated. Thanks!

Neptonic Systems also sells fin rails online: http://www.neptonicsystems.com/fin-rails.php

If you don't come right with those also have look at automotive rubber trim. Some companies stock some really interesting rubber mouldings.
 
landshark sa

landshark sa

Well-Known Member
Feb 15, 2011
353
183
83
@landshark sa thank you very much for all those details !
It seems I will have to make quite many try to get a pair of fins that works for me, so let's get working !

You're welcome!

Enjoy the learning process. It's lots of fun and hugely rewarding plus its feels like its my birthday every time I de-mould a new part :)
 
daweasel

daweasel

Member
May 22, 2017
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0
11
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@landshark sa yeah I can almost feel it, I'm so excited by this project !

I had another question, what are the possibilities for cutting the fin to right dimensions/shape ? Is it easier to cut it right before the lamination and to just finish it after ? Or should I laminate a rectangular shape and then cut it (which does not seem easy) ?
 
landshark sa

landshark sa

Well-Known Member
Feb 15, 2011
353
183
83
@landshark sa yeah I can almost feel it, I'm so excited by this project !

I had another question, what are the possibilities for cutting the fin to right dimensions/shape ? Is it easier to cut it right before the lamination and to just finish it after ? Or should I laminate a rectangular shape and then cut it (which does not seem easy) ?

It depends on how complex your layup and what weight and type fabric you work with, for example unidirectional fabrics are easier to handle and cut than weaved but I don't think that you'll be able to get away from cutting the cured laminate.

If you are making bi-fins you also want to consider symmetry, both fins should have exactly the same layup and dimensions. Trying to cut and layup multiple layers of fabric to be exactly the same may prove to be difficult.

If you use a tool like a jigsaw or Dremmel cutting the cured laminate is actually very easy, just make sure you use a mask or respirator as the dust is hazardous.
 
landshark sa

landshark sa

Well-Known Member
Feb 15, 2011
353
183
83
Ok, seems like I won't avoid the respirator and putting dust in every corner !

I rig up a vacuum cleaner while cutting to get rid of most of the dust.

Do you know if cutting cured laminate with metal hand shears like those (http://www.lighttoolsupply.com/cata...l-Master-Shears?productID=6825&categoryID=125) can do the trick ?

Those seem like pretty heavy duty shears so I don't think they will initially have a problem cutting through the laminate.

The problem however is fibreglass, carbon and especially aramid laminations are very abrasive so you will find that the the shears will dull extremely quickly. So what will happen is once its blunt you will able to produce enough force to split the laminate but it will essentially be breaking the fibres and the resin matrix thus creating delamination on the edges of the fin which will lead to water ingress and ultimate fin failure.

Because of the abrasive nature I use tungsten carbide jigsaw blades and cutting wheels which last a bit longer standard cutting edges.
 
daweasel

daweasel

Member
May 22, 2017
8
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@landshark sa Thanks for your insight, I will probably try the hand shears and see how it goes. I heard about the highly abrasive nature of carbon but thought fiberglass wuld not be that hard to cut. Anyway, I'll try and see !
 
Y

yohannyo

Member
Oct 8, 2017
1
0
11
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Hi all,

This is a amazing thread thanks all for all this info.
So i am also planing to make my own Fins out of Fiber. Does someone know how to integrated a camo design in the fiber glass? Does printing a design on a normal paper sheet and put it in between layers would work?
 
bluedvr

bluedvr

Well-Known Member
Dec 5, 2004
8
3
93
49
  • Following the thread for a few years, I finally decided to make my own using a few layers of 5.6oz 2x2 cloth. There’s a couple of numbers that keep appearing when measuring fin thickness .030 inches at tip and .070 inches at foot pocket. So this is what I tried to achieve.
  • I have also found that maintaining a proper seal on parts to be infused the most important aspect of this process. But once seal is achieved smooth sailing.
  • I made a blank of carbon fiber and cut my fins out using an abrasive jigsaw which worked like a charm.
 

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bluedvr

bluedvr

Well-Known Member
Dec 5, 2004
8
3
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Thanks to all those people who provided input which was the most valuable part of the process.
 
T

tattoum

Active Member
Oct 21, 2015
6
1
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Hi all,

This is a amazing thread thanks all for all this info.
So i am also planing to make my own Fins out of Fiber. Does someone know how to integrated a camo design in the fiber glass? Does printing a design on a normal paper sheet and put it in between layers would work?
Trucs tout fond à vert thon paper, it World. Tedted
 
bluedvr

bluedvr

Well-Known Member
Dec 5, 2004
8
3
93
49
Hi all,

This is a amazing thread thanks all for all this info.
So i am also planing to make my own Fins out of Fiber. Does someone know how to integrated a camo design in the fiber glass? Does printing a design on a normal paper sheet and put it in between layers would work?
 
bluedvr

bluedvr

Well-Known Member
Dec 5, 2004
8
3
93
49
How about using camo printed on nylon so that it can absorb some epoxy, I think the paper will foul the layup.
 
T

tattoum

Active Member
Oct 21, 2015
6
1
38
57
[QUOTE="tattoum, post: 975153, member: 47774"
 
Bobsy

Bobsy

New Member
Feb 18, 2022
2
0
1
22
Hello all, my name is Jacob and I've read this thread over the past month or two when I get time.
My father and I have decided to begin our venture of creating fibreglass fins at home also, we are currently in the process of selecting our fibreglass and epoxy while discussing different forms of mould and vacuum pump.
We think we are going to begin much like Zmagoj did by using an old refrigerator pump.
I would like to thank everyone here for posting and making such insightful and helpful comments on the topic, thank you so much.

I'll keep you posted,
Jacob.
 
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