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Selfmade fiberglass fins

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Z

Zmagoj

New Member
Mar 30, 2010
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Hi all

I am a newcomer here in both deeperblue and freediving, but I have some experience with fiberglass which I want to share.

Searching the web I hardly found any thread regarding homemade freediving fins. Thus I decided to give it a try and make one. I've already started the thread on the slovenian forum "H2O team":

Link to thread (sorry, but google transate doesn't work well)

To have a chance to get in touch with more people and get more constructive comments about my fins I decided to start a parallel thread here.

Regards,
Zmago
 
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Z

Zmagoj

New Member
Mar 30, 2010
55
10
0
In the first attempt I used 5 layers of 200 g/m2 fiberglass cloth, with its fibres oriented along the blade. As a shape blueprint I copied the BLEU TEC carbon fin.
As seen from the video, the blade lacks stiffness:
[ame=http://www.youtube.com/watch?v=EhDShLQmcgo]YouTube - Homemade fiberglass fin[/ame]

In the second attempt I used 7 layers of 280 g/m2 cloth, tailored into square and triangular shapes. The fibre orientation was mostly 45° regarding the longitudinal axis of the blade.

The result was a rather stiff blade:
[ame=http://www.youtube.com/watch?v=s75YqDc1LpU&feature=related]YouTube - Homemade fiberglass fin-part 2[/ame]

For the third attempt I am considering the idea to remove the top and bottom cloth, thus get a softer blade positioned somewhere between the above two.

Regards,
Zmago
 
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Old Man Dave

Old Man Dave

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Feb 19, 2005
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Great idea. Are you using bi-axial cloth and are you using polyester or epoxy resin? I assume you are using some form of mould to get a flat surface and a uniform thickness? How about a few pictures of the making process.

Good work.

Dave.
 
podge

podge

Always Hungry
May 16, 2006
6,225
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Zamgo firstly welcome to Deeper Blue.
I’m no fibre glass boffin but this is some good stuff with the fin blade’s and I’m sure that it’s not just me that’s finds it of interest.
Keep us posted on the outcome of your work and well done so far.:)
 
Z

Zmagoj

New Member
Mar 30, 2010
55
10
0
Are you using bi-axial cloth and are you using polyester or epoxy resin? I assume you are using some form of mould to get a flat surface and a uniform thickness? How about a few pictures of the making process.

The process I used is no hi-tech and is based on a set of simple inexpensive technics. A professional would probably find my approach amusing, but it works.

So from the beginning:

1. The first stepis to determine the shape of the fin. I simply used a commercial carbon fin and draw its silhouette on a cardboard and measured the angle on the footpocket side.

2. Make the upper and lower mold out of wood (flounder).

3. Cut the layers of fiberglass out of biaxial - keper (I hope I spelled correctly) cloth.


4. Prepare the foils which protect the laminate from being glued to the mold.
A mylar foil can be used, but I had non available. Therefore I used cellophane foil and added a thin film of solid soap on the surface that is in contact with the laminate.

5. Mix the epoxy resin with the hardener and lay the mylar foil on the lower mold. Start laying the fiberglass cloths and wet them with epoxy (one at a time). Lay the second mylar foil and check, that there are no bubbles (or at least not many) in the epoxy. Cover it with the upper mold and place some heavy things on top of it.


6. Wait at least 24 hours, or better 48 hours. The laminate has better mechanical characteristics if curing at higher temperatures (eg 60-90°C). Anyway, normal room temperature do just fine.

The result is a raw laminate which needs just the final trim.

Regards,
Zmago
 

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L

leven

New Member
Aug 4, 2009
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looking good! but is fibreglass really that flexible? I have only worked with carbon so far and with more than tree layers it becomes really stiff, i'm making a mono thats tree layers at the bottom and 5-6 by the foot-part, and the foot-part doesn't bend at all..

What kind of epoxi/resin do you use?
I use an epoxi thats used for boats (water-resistant, NM 275E) and 200g twill weave carbonfiber..
 
Z

Zmagoj

New Member
Mar 30, 2010
55
10
0
looking good! but is fibreglass really that flexible? I have only worked with carbon so far and with more than tree layers it becomes really stiff, i'm making a mono thats tree layers at the bottom and 5-6 by the foot-part, and the foot-part doesn't bend at all..
What kind of epoxi/resin do you use?
I use an epoxi thats used for boats (water-resistant, NM 275E) and 200g twill weave carbonfiber..

Fiberglass as well as carbon could be bend without worrying to crack it, if it is properly molded. I use an ordinary epoxy designed for aviation (I don't see any mayor difference in the final product).

You've probably used to heavy carbon. You should go for thiner one, or use a higher compression when molding. I was looking the C4 fin, which uses really heavy cloth, but it is probably curing under heavy compression/vacuum to get a proper thickness.

The difference I see between glass and carbon is the strength which is much higher at carbon. To achieve the same strength, more fiberglass must be used, what leads into thicker fin.

The main two parameters which control the stiffens of the fin are
- the strength of the fibers and its orientation
- the thickness of the fin
The higher the thickness the stiffer the fin is. To get strong and flexible blade, you should produce a thin fin with as many fibers compressed inside as possible. There is also hidden the difference between carbon and glass fin.
Due to higher strength, the carbon fin is thiner for the same strength and stiffness.

The main thing that makes fin good/bad (assuming the stiffness is OK) is its ability to store energy when kicking (spring) and releasing it between kicks. There the composites are much better then ordinary plastic. The carbon fin with its thinner fin also consumes less epoxy resin which kills the absorbed energy, but the difference is very small.

To conclude
I think, that any composite is better than plastic (for fin material). But the differences between carbon, glass and kevlar are very small and not important. The most important is the technology of molding and the the shape of the layers.

Regards,
Zmago
 
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Z

Zmagoj

New Member
Mar 30, 2010
55
10
0
I forgot something important.

When using carbon, pleas take all the safety precautions (breathing mask..), or you will deal with a lung cancer in 20 years.

It is also highly recommended for fiberglass.

Regards,
Zmago
 
foxfish

foxfish

Silver Smoker
Dec 31, 2005
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I forgot something important.

When using carbon, pleas take all the safety precautions (breathing mask..), or you will deal with a lung cancer in 20 years.

It is also highly recommended for fiberglass.

Regards,
Zmago

Hi Zmago, great project.:)
I have only just started using carbon but I have noticed it produces a very fine congesting dust while sanding or grinding :yack
 
Old Man Dave

Old Man Dave

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Feb 19, 2005
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As I've already said - great thread.

I'd thought about doing something similar in the past and the only difference I thought about was adding spacers between the the top and bottom formers (moulds). Rather than just relying on a lot of weight (pressure) to compress the different thicknesses of wet glassfibre into a uniform sheet, spacers would ensure or control the finished thickness. That way you could introduce a controlled taper over the length or even side to side (making left and right handed bias fins?). You'd need to vary the size/numbers of layers of cloth as well but you'd achieve more consistant results.

Trouble is each fin is going to cost a fair bit and ideally you need to make 20 or 30 and test them out before you got it right. That's what originally put me off doing it myself.

Dave.
 
Z

Zmagoj

New Member
Mar 30, 2010
55
10
0
As I've already said - great thread.
Trouble is each fin is going to cost a fair bit and ideally you need to make 20 or 30 and test them out before you got it right. That's what originally put me off doing it myself. Dave.

Thank you Dave.

I hope that the third (or fourth) iteration will be satisfactory, at least for my needs.
The reason for posting my project is to show someone, who is starting with similar aim, where his starting point should be - to save effort/cost.
I am aware, that the fin won't be perfect, but it will probably fulfill may needs.

I am planning to build the third variation in the end of the next week, and then post the results.

Regards,
Zmago
 
foxfish

foxfish

Silver Smoker
Dec 31, 2005
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Zmago, I cant see where you mention using peel ply? This might help to achieve a more uniform product.
 
Phil Herranen

Phil Herranen

hguns
Jan 31, 2010
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Zmago, I cant see where you mention using peel ply? This might help to achieve a more uniform product.

peel ply and a vac set up will give you a far stronger fin . all the weight you put on your mold wont even add up to 1 psi ( remember you would have to have a column of sea water 33' tall to = 15 psi) you want just enuff resin it fill the voids in the fabric and no more
phil
 
Z

Zmagoj

New Member
Mar 30, 2010
55
10
0
peel ply and a vac set up will give you a far stronger fin . all the weight you put on your mold wont even add up to 1 psi ( remember you would have to have a column of sea water 33' tall to = 15 psi) you want just enuff resin it fill the voids in the fabric and no more
phil

I agree, the best option would be vacuum bagging, but I wanted to keep it simple.

The above comments are just what I wanted when I started the thread.

The main reason for not using the vacuum is because I don't have a vacuum pump (I can get it from a friend).
Vacuum would certainly squeeze out more excessive epoxy, but does this really affect the performance of the fin?
I think, that the fins are far too strong for the purpose already. During the lamination process I was very careful not to apply too much resin. I used appr. 160g for the first and 220g of the mixed resin for the second iteration.

Peel ply gives you a rough surface. Better option is to use a special perforated foil which is then covered with peel ply. Because I hadn't had the foil, I tried with the cellophane and succeeded.

If I am doing something wrong please write/suggest... I would be happy to hear any opinions.


Regards,
Zmago
 
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griswold

griswold

Well-Known Member
Jul 29, 2005
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I am interested in attempting to make my own blades as well. Phil, I know you've done some great work with carbon on your guns. Have you tried fin blades yet?
 
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Z

Zmagoj

New Member
Mar 30, 2010
55
10
0
The third iteration landed somewhere in between the first two.
The attached picture shows the bending curve of my fin and the Bleu tec's carbon fin.
It is still a bit soft in comparison to the carbon one, but now I think I have the proper recipe now.

The video:
[ame=http://www.youtube.com/watch?v=vjrG5KZ-aH8]YouTube - Homemade fiberglass fin-part 3[/ame]

For the next (and indeed last iteration) I will again add the outer layers and remove/rearrange some of the inner layers. I am also planning to conduct some water tests with the 2 and 3 iteration.

I hope, that the next iteration will be satisfactory, because I am loosing my elan here.

Regards,
Zmago
 

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Phil Herranen

Phil Herranen

hguns
Jan 31, 2010
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I agree, the best option would be vacuum bagging, but I wanted to keep it simple.

The above comments are just what I wanted when I started the thread.

The main reason for not using the vacuum is because I don't have a vacuum pump (I can get it from a friend).
Vacuum would certainly squeeze out more excessive epoxy, but does this really affect the performance of the fin?
I think, that the fins are far too strong for the purpose already. During the lamination process I was very careful not to apply too much resin. I used appr. 160g for the first and 220g of the mixed resin for the second iteration.

Peel ply gives you a rough surface. Better option is to use a special perforated foil which is then covered with peel ply. Because I hadn't had the foil, I tried with the cellophane and succeeded.

If I am doing something wrong please write/suggest... I would be happy to hear any opinions.


Regards,
Zmago

the extra resin from not vacing will cut the life of the fin in half .the extra resin resist flexing and magnifys the stress on the glass in those spots causing cracks

I am interested in attempting to make my own blades as well. Phil, I know you've done some great work with carbon on your guns. Have you tried fin blades yet?

i have made a quite few over the years ,and since i buy rolls of glass for boards (and have bags of cutoffs )the materials are always on hand and cheap (not more than $20 a pair). but you have to draw a line on projects at some point .between my hvac company and building guns ,i work around 14 hours or more a day 7 days a week .
phil
 
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Mr. X

Mr. X

Forum Mentor
Staff member
Forum Mentor
Jul 14, 2005
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Cool thread. Got to admire the resourcefulness of the DIY'ers on the forum. I'd like to try fibre glass fins but was shocked by the prices I saw in the on-line stores. [That said, I can't really my old Beuchat plastic bladed fins - they've put up with an amazing amount of abuse over the years & just keep on going].

Phil Herranen, maybe time to hire some help? Lot of folk looking for work at the moment. (Nice spearguns ;)).
 
Z

Zmagoj

New Member
Mar 30, 2010
55
10
0
So, the decision has been made. I will follow the Phil's advice and give it a try with vacuum bag. I am still not certain about using the peel ply - waiting for an expert I know to answer this issue.

I will post the decision.

The project is going to be postponed for a while, because I have to build a vacuum pump, but it will continue.

Regards,
Zmago
 
Old Man Dave

Old Man Dave

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Where I worked a few years ago I had a large vacuum machine that I used a fair amount. You put stuff actually inside of it. It worked well. I never actually used vacuum bags.

Is an ordinary vacuum cleaner powerful enough to use if attached to a strong poly bag? Think mine at home is 1300 watt motor rating.

Dave.
 
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