Video of my first infusion - Need Advice on How to improve (Dive Fin)

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#1

Hi Composite Experts,

I have zero experience with composites previous to this forum. I really like it here, and have learned so much. I decided to try creating a dive fin out of carbon & fiber glass. I jumped straight into infusion without ever doing wet layups, or other methods.

Here is a video of my first infusion. I am trying to learn on how to improve. I really would appreciate anyone who could give me some pointers or some tips on how to improve my infusions. I know I made a lot of mistakes such as not clamping my lines, and not having PVA/semi perm.

I used US Composites 635/Low resin and a refrigerator pump which pulls 28.5 at sea level but only 25" at my elevation. This particular video which you are watching I detected a leak midway through which I quickly fixed. I heated up my resin and mold because this is what the US Composites website says to do. I believe it also helped it flow faster.

I am trying to produce a dive fin which is strong and flexible. Here is what a professional fin looks like:

Here is the video link: [ame=“http://www.youtube.com/watch?v=QvVMgAT_WtA”]http://www.youtube.com/watch?v=QvVMgAT_WtA[/ame]

I have since ordered some resin made for infusion from another website. I also have PVA, which I will use for my next infusion. I am not going to use any dye for my next fin, because I will be using more carbon fiber. Do you think it is best to keep the carbon fiber on the inside or the outside layers when using carbon fiber and fiberglass?

Also in the video where it says “Release Film” it should Say “Peel Ply”.

#2

Great job on the first run. You definetely have the basics down. Not sure of this but I believe the carbon should be on the outside using the fiberglass as a core and to have the carbon finish.

#3

Very well done indeed!

Are you making these for production?

As for layup, you could maybe exclude the glass and experiment with diolen, as its very flexible and its commonly used for kayak paddles. It’s also cheaper than carbon, maybe do a sandwich of 200g carbon, 200g Diolen, 200g carbon.

#4

You might try pulling across the fin rather than down the length of it if you want to speed up the process. I can’t really tell how much space you have on the sides to set up that way but I like to get the infusion done as quickly as possible and the shortest route is usually the fastest. In addition to the time saved there is less pressure differential in a short path and therefore more even resin distribution.

#5

Do these fins fit into a rubber. Curios

#6

Well done. Couple of thoughts:

-1. Make sure your bag is airtight. This is key to the infusion method. Do a droptest to check.
-2. Clamps: fold the hose twice (so it is Z shaped) and put some tape around. Presto…
-3. Get a perforated film with more perforations. This one looks like P3 perforation. You would like P or P1, or MP22.
-4. No idea of the infusion speed vs curing speed. You might want to infuse slower, for better impregnation. (carbon is slow in impregnation)

Above are hints to sort out the infusion. But for your first infusion without outside assistance: I am impressed. Well done.

For the “annealing” (which is called postcure in composites). Kudos for you. You show that an oven is a simple thing, and should not cost too much money.

For the part itself:
Your challenge is finding a laminate schedule that works, in terms of strength and bending. If you place the carbon more outside, it gets stiffer. Get the part thicker, it gets stiffer. It would be nice to have a broken fin from somewhere. If you can get one, do not hesitate. Cut small pieces out, put them in a porcelaine bowl, and fire them at 350C (is that 800f?). This will burn away the resin, and then you can carefully weigh the fibers, and determine the laminate scheme.

Also Vf (fiber to volume ratio) can play a role in this part. Learn how to influence that during infusion (you need clamps)

Also you can add an extra layer on the first halve of the fin, to get different properties there.

One last remark: About you flopping the part around: You never had a carbon splinter in your finger, do you? (makes you sing songs and do nice dances)

#7

Hello,

Penetrator fins is working with the MTI hose, I think he is also a member in this forum.
Very good for your first infusion.
I think the flow direction is fine and the speed is not too fast. More importantbthan the speed is that you have a perfect vacuum >20mbar absolute.
Build a brake zone at the end where you evacuate the air or use the MTI hose.
Also like herman said use clamps or z fold the feedline. When you open it let the resin travel to the fold and wait that the pump can evacuate the air from the feedline.
A compressor from a refrigiator is fine for wet layup but the vacuum it creates is only about 300mbar abs. Thats not high enough for infusion.
The cheap oil lubricated airco vacuum pumps from ebay or habour freigth are fine.

#8

When I wrote previously about pulling across, it wasn’t a comment on the speed of fiber wetting so much as it was about reducing process time. I’d bet dollars to donuts that you noticed a major shift in wetout in the last half of the infusion. The first few inches are exciting, after that it’s a little like watching paint dry. I like to reduce process time whereever possible.

Certainly, there are variables such as fiber wetout and void inclusions that can vary with the speed of the resin flow but it’s been my experience that the variables will be there regardless of the path so you might as well make the flow path short. If you pull across the fin, you’d be done with the entire fin in about the same amount of time as it takes for the angled portion to infuse.

A side benefit is if you do find yourself with an air leak, the path for bubbles is much shorter. While we try to get a perfect seal, sometimes a leak develops. A bit of tacky tape can fix the leak and sometimes flowing more resin can remove the voids in the part.

As the old saying goes, there is more than one way to skin a cat. If you are comfortable as is, great. Just offering an observation.

#9

I see he heats up the epoxy pot and the infused laminate with a dryer. Is it convenient to heat up the laminate if some section is delayed with the resin flow?

#10

Can anyone comment on the type of resin I am using? I am using epoxy resin, but am wondering if a VE resin would be okay for this type of product?

#11

Stick with epoxy, it has a higher elongation than VE.

#12

I have same question, I wonder, if it’s good heat a portion of resin, without heating the rest.