Hi Experts,
If you were going to vacuum infuse a dive fin (which needs to be very flexible) and snap back quickly when flexed; which type of resin would you use?
Here is an example of what I am trying to make:
And on a second question. What type of weave / carbon fiber do you think this fin is?
Use an epoxy with 3.5-4.5% elongation, such as west system’s epoxy.
The weave in your second pic is a plain weave (12k or above filament count).
HTH
a high elongation epoxy indeed, and the weave looks like a spread tow weave, like oxeon makes.
Also, for a part like this vac infusion isn’t really justified (other than for practice).
Just wet lay on some aluminium/glass with a good surface finish and use a caul plate. You can either place some weights on the caul plate, or if you have a vacuum pump available, just bag it for the cure.
There also high elongation to break Vinyl Ester resins up to 18-19% that will do the job nicely. Check with you local resin supplier.
A few that spring to mind AOC, Ashland, Reichold and CCP. Suggest also a very flexible clear coating should also be available to finish your part, post moulding.
#1. High elongation epoxy seems to be the general conciseness. Vinyl Ester or Epoxy…?
Also, I was planning on doing vacuum infusion, but Justin suggests a wet layup. Wouldn’t infusion provide a better quality product? I do have a vacuum pump, but don’t have (or know what is) a caul plate is.
Please more feedback suggestions on resins. I don’t have a local resin supplier (I live in Hawaii) so I need to order everything. Thanks so much everyone.
A caul plate is just a flat plate placed upon the laminate in order to provide a secondary flat surface. This should be rigid enough not to bend when the vacuum is applied… You can use this in contact with your laminate surface or place non perforated release film between the caul and the laminate. Always use a release agent on the caul.
Also, i place an extra ply in the outer edge region ( say 1/2" ) to help support the caul and to prevent bending.
I’ve had good results with both wet lay and infusion, but infusion costs more… I’d suggest you do what you feel more comfortable with…
I have made a pair, upon inspecting mass manufactured fins closely. Noticed it is 1.5mm at one end (foot side) and gradually thinning down to 0.75mm on the free end. So I had to make optimization of how many layers carbon to use and calculated length of the each layer for vacuum infusion, since I know what thickness I get from certain layer with vacuum and measured how gradually original fin gets thinner. Mine came out little bit more stiffer than the original one they gave me, but over all pretty much accurate, because even original fins offers different stiffness recommended for different weight of people.
Although my success, and already available polishes stainless steel mold with 22 degree bend for the foot connection; I did not continue to produce anymore. It stayed as an experimental job for a special order. Because cost with vacuum infusion came high and figured it is not profitable unless manufactured in mass with advanced molds systems. Mass manufacturers probably using heated plates with hydrolic press.
What do these sort of fins run per pair?
I’m interested in this sort of resin but am looking for higher elongation. I found one that gives 80-110% elongation in tension. Not sure if you need this much flexibility, I would think not.
Just looked… $300-$$400 AUD per pair… there should be some profit margin in there?
You will find that Larry from Penetrator Fins (from your first picture) is on these forums, though I’m not sure how often he gets on here. You could flick him an email, he has been very helpful to me in the past, he may be willing to offer you some insight into what resin he uses: