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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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Hi pvilela,,

yes of course, this helps a lot...thx..

I have only 300 gr. UD available, not 200 gr...
So what do you think about my version 1.2 and i remove layer 2 ?

Do you think its possible to grind them a little if they are to strong? Of cours i will destroy the biax on the lower side but better then not to use? ( its the first try...)

Where did you buy your rubber rails?

regards,

Henning
 
Strange, its usually available in the same place where u get the rest of materials. I know vendors in Europe, but it wont help u since you are in Hawaii :)
 
Jamestowndistributors.com and Fiberglasssupply.com sells unidirectional fiberglass!
 
Thanks Cid for the sources.

Sorry to re-live this thread, but I just wanted to let people know that I am about to partake in this project.

I just built a vacuum pump out of a refrigerator compressor. I am now adding the necessary products to my shopping carts. It is unfortunate that I can't find a single online dealer that sells all of the products which I need.

My question is about the type of fabric to use. I have noticed that Zmagoj has spoken very favorable in the use of unidirectional cloth. Does anyone know whether I should use a layout of all unidirectional cloth, or will twill and plain cloths offer similar performance?

The hardest part about this project is estimating the amount of layers that you will need, the order of the layers, and the types/weight of the cloths to use.

I am leaning towards unidirectional cloth because of Zmagoj's recommendation but the cloth is just so hard to find. Using twill or plain cloth is more cost effective and they have it in more various weights.
 
Does anyone know what I can use in place of flow media? Can I go to a fabric store and buy something that might work in its place?


Edit: I have found online that garden netting, mosquito net, and window screen can be used. If anyone can comment on these options it would be greatly appreciated.
 
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Okay I have all of my supplies now. I am using:

1 layer of 11oz (310 grams) unidirectional carbon fiber

and am unsure on how many layers I want to use with my 8.5oz (240grams) of twill glass cloth.

I know I will want thicker glass near the foot pocket but am still deciding on the layout.

Other uncertainties
  • I dont have PVA Release Agent. Will using car wax be okay? Or should I put release film over my glass mold
  • I dont have green mesh. I am going to try using window screen. Anyone comment on a green mesh flow media alternative?
  • I am unsure on how to cure the resin once the infusion is finished.

Anyways, I am going to try doing some test runs initially.
 
Big Island,

A good supply house for doing composites work is here: General Composites & Recreation | Airtech Global

They will have everything you need to do a vacuum infusion job.

However, vacuum infusion is not necessary for small jobs like making a pair of fin blades. It is just as good to lay it up wet, then vacuum bag and debulk the material. It will save you a lot of equipment and wasted materials if you do it this way. The vacuum infusion process is optimum for large composite jobs.

My recommendation, is to lay it up wet on your mold or cull plate, whichever you are using. Then layer on top of that your peel-ply, bleeder cloth, barrier, the breather cloth and finally the vacuum bag on top. Apply 20 to 24 inHg vacuum and wait for the resin to cure. Either solid or perforated barrier materials should be okay for a job like this, just make sure you have a flow path from the breather to the bleeder layers.

I would recommend a release wax over car wax. If you use car wax, make sure it is a carnauba wax. As for the PVA question: the answer depends on your mold. If you are using a metal cull plate, you can probably use wax only and be fine. If you are using a composite mold (especially if it is valuable to you), the PVA is a nice bit of protection to have.

Ron Smith - Smith Aerospace Corp.
 
Hi Revan!

Thanks for the response. I have been doing some test runs with vacuum infusion, and am willing to give the wet layup a try.

So far none of my fins have come out the way I want. They are all too hard and brittle without the right flex. I am using US Composites 635 resin with slow harderner.

I think this might be my problem. Can you suggest a resin that would work good for dive fins using infusion or wet layup?

I have already invested so much money into this project that I want to see it through and make a complete fin!
 
So far none of my fins have come out the way I want. They are all too hard and brittle without the right flex. I am using US Composites 635 resin with slow harderner.

I think this might be my problem. Can you suggest a resin that would work good for dive fins using infusion or wet layup?

I doubt the resin is the issue. Too hard and brittle... this is usually attributed to the material not being properly debulked [i.e. - too high of resin content] or too much material overall [i.e. - too many plies of reinforcing material].

I don't like carbon fiber for dive fins. Carbon fiber composites are very stiff, and fins need to flex. To get the flex, the blade must be very thin which makes it fragile. Unidirectional tape exaggerates the problem if you are laying the fibers lengthwise. Laying it at 45s will help, but then why not just use a balanced weave?

Personally, I think fiberglass is a better material to use for this application. It is less expensive too. If you want something between your average fiberglass and carbon-fiber, you could consider using using s-glass (most people/applications use the less expensive e-glass).
 
Here is a video of my first infusion. I have much to learn. I think my fin is a little bit too soft. I am looking for advice on how to improve. Thank you.

[ame=http://www.youtube.com/watch?v=QvVMgAT_WtA]First Infusion - Dive Fin - Need Advice and Feedback - YouTube[/ame]
 
...I am looking for advice on how to improve...

I would recommend using a resin runner an one side of the fin blade and a collection tube on the other side. Flow across the fin instead of lengthwise. Use spiral cut PE tube to make the flow channels along the sides. Are you using a flow mesh? From the video, it looks like you are just flowing through the fiberglass without a flow mesh. Flowing lengthwise like you are, a flow mesh will definitely help speed up the fiber saturation.
 
I would recommend using a resin runner an one side of the fin blade and a collection tube on the other side. Flow across the fin instead of lengthwise. Use spiral cut PE tube to make the flow channels along the sides. Are you using a flow mesh? From the video, it looks like you are just flowing through the fiberglass without a flow mesh. Flowing lengthwise like you are, a flow mesh will definitely help speed up the fiber saturation.

Thanks for the advice Revan. You are the second person to suggest this method. I am definitely going to try it on my next infusion this week. I did not mention the flow mesh in the video, but yes, I am using green airtech media flow media.

And yes...... I left the heat gun on for about 5 or 6 hours. My electricity bill will be high this month. My next resin cures at room temperature, so maybe I won't need to use the heat gun. :)
 
The high temp heat gun in a cardboard box is a fire hazard, so keep a close eye on it. I use room temp resins, but I still like to use a box with a hair dryer to speed up the cure. My box gets up to about 135 to 140 F with the hair dryer on low, which is awesome conditions for room temp resins. I get a full cure in less than an hour.
 
The high temp heat gun in a cardboard box is a fire hazard, so keep a close eye on it. I use room temp resins, but I still like to use a box with a hair dryer to speed up the cure. My box gets up to about 135 to 140 F with the hair dryer on low, which is awesome conditions for room temp resins. I get a full cure in less than an hour.

Revan, you are absolutely correct about it being fire hazard. That is a great point to point out, for anyone attempting to do this themselves. I keep two fire extinguishers close by just for this reason. My resin does not cure at room temp. Even after the heat cure, the fin does not completely cure until about 3 more days at room temperature.

My next resin is a room temperature curing resin, with a better viscosity. I am excited to try it.
 
I go the other way.
 

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hi zmagoj, i am very interested in fiber glass and carbon freediving fins and i found this video on youtube, please telle me if it is good or no so that we can help peaople :
 
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