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07-26-2017, 02:36 PM | #1 |
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Pre Preg Carbon Wrap
Anyone use Pre-preg Carbon Fiber? I know it has to heated. Not sure the laminates will survive the 200F temp.
Thoughts??? Kevin |
07-26-2017, 02:46 PM | #2 |
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Re: Pre Preg Carbon Wrap
I would look into the temp tolerances of your adhesive once it has set. I haven't done any CF wrapping, but im sure other that have can tell you if the moisture in the lumber could cause any issues.
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07-27-2017, 08:37 AM | #3 |
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Re: Pre Preg Carbon Wrap
Pre preg needs to be stored in a freezer, so while it's a boon for the composites industry it's rather impractical for hobbyists.
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07-28-2017, 03:13 AM | #4 |
Shooter & Shooter
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Re: Pre Preg Carbon Wrap
I think a lot of wood would outgas at the high temps needed by prepreg, so that would possibly make it a no-go. If you want to get fancy, then wrap dry and infuse with room temp curing infusion epoxy. And then you could possibly do a post-cure at a higher temp later on.
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07-28-2017, 04:33 AM | #5 |
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Re: Pre Preg Carbon Wrap
If you want to wrap your gun with Carbon Fiber, by far the easiest and best way is to use braided CF sleeves. They will create a seamless CF cover that contours around the shape of your gun. According to the Carbon Fiber experts, a braided sleeve is also the strongest and most efficient way to add CF to a changing shape (as in a speargun). On areas where the gun is thinner, you will end up with more CF as the sleeve constricts ... and where the diameter is higher ... it will put less CF ... so it adds strength where you need it most. Say you are using a 3K braid ... on areas where the stock thins down (around the trigger) the 3K might become 6K. I think you can get away with adding a CF sleeve without the use of a vacuum bag (although I haven't personally tried it). I think it can be done by just wrapping the sleeve with heat shrink tape and blowing hot air on it with a heat gun or a hair dryer. Obviously much better results can be had with a proper laid up vacuum bagging setup ... but if you don't have that setup and still wanted to CF your gun, that might be a good option.
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07-28-2017, 04:54 AM | #6 |
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Re: Pre Preg Carbon Wrap
Thanks for the responses. I recently did my first carbon wrap with Soller Composite sleeve.
I used vacuum bag on first layer, had some bridging issues at the ends. Getting a nice tight beat seam at the end (muzzle) prove to be a challenge. The next layer I used the same material but a heat shrink tube. The heatshrink itself was fragile and tore. While adjusting for that the carbon wrap shifted and wrinkled which I didn't catch until afterward. The gun is finished and with some epoxy sculpt mix I overcame my mistakes. The learning curve was steep and I looked at pre preg because it is premixed, and the seams are sharp and clean. The storage in a freezer is not a problem. But I have some real concerns about the 212 F cure temp. I doubt the gun laminates would survive that. Thinking of using a solid blank and pre curing it first to out gas it, then go with the carbon pre preg. |
07-28-2017, 05:12 AM | #7 | |
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Re: Pre Preg Carbon Wrap
Quote:
If you want to go the pre-preg route ... you should do your laminates with a high heat epoxy first. Conventional epoxy might soften with high heat. To have a good structural shape you would also have to go over the seam. I actually think it will be much harder to do than just using a sleeve. I have done about a dozen guns with CF sleeves, and like many procedures, there is a learning curve to do it properly ... but even the first one I did was perfectly functional, although aesthetically not as pretty as the last one. |
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07-28-2017, 06:16 AM | #8 |
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Re: Pre Preg Carbon Wrap
Thanks, that's great advice. I won't be using shrink wrap again. I know where I made my mistake on the vacuum bag. I have heard of the inverted sock method before. I think I will try that on the next gun. I like the look and the strength of the carbon fiber.
I have a design in mind for Bluewater that is tapered and thin, with the polyplast band set up. My last gun was a conventional 5/8 band roller with four 3/4 inch x 12 inch long bands on the polyplast. It was smooth and strong when I tested it. Thanks for the help |
07-29-2017, 01:47 AM | #9 |
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Re: Pre Preg Carbon Wrap
Majd, what sort of actual vacuum time required with the 209 hardener?
Looking at cheapest/most compact option for bagging sleeve and handle here, something small but with sufficient run time. Got plenty of pressure here with Bauer and tanks, but no SUCTION……. |
07-29-2017, 03:15 AM | #10 | |
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Re: Pre Preg Carbon Wrap
Quote:
If you don't have a vacuum pump you can get away with a compressor and add a special valve that allows the compressor to suck up vacuum. Of course a compressor is not designed to be left on over night ... so I would just use faster cure epoxy and have a setup which the seal is very good where I can just turn off the vacuum without having the bag leak. With sleeves that is pretty easy to do but with a typical vacuum bag it is more difficult to have a 100% leak proof bag ... so maybe you would need to keep an eye on the bag for a while as you seal of the leaks. Personally I just leave the vacuum pump on as this allows me to forget about it and do something else. Last edited by spearq8; 07-29-2017 at 03:39 AM. |
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07-29-2017, 07:24 AM | #11 |
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Re: Pre Preg Carbon Wrap
Yo Sheets, I don't think Pre-Preg is the right option for the home builder. It requires a long Auto Enclave to maintain @220 degrees Fahrenheit and pressure, and I'm quite sure if you cut the stock in half and put it in your oven, the missus is going to be unpleasant. Also. A wood core brought up to 220 is just not the best idea for our purposes (Straight as an Arrow). A wooden stock brought up to 220 is a good way to make a bannana. To say nothing about offgassing.
I've seen some amazing AutoEnclaves locally. Rhode Island has a long history of Boat and Mast Building. I saw an AutoEnclave 160' long the other day which was pretty impressive.. With Prepreg, the idea is to Mould your shape with pure inert composites. Then to Cure that shape in the Auto Enclave under Heat and Pressure. It's a completely different process then what you are talking about. What you want to do is Resin Infusion. Anyways. In shop all day as usual.. if you're in neighborhood. NorEaster next few days.
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07-29-2017, 08:21 AM | #12 | |
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Re: Pre Preg Carbon Wrap
Quote:
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07-30-2017, 01:00 AM | #13 |
Shooter & Shooter
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Re: Pre Preg Carbon Wrap
- For turning pressure into vacuum, look into venturi pumps or just build a cheap vacuum pump yourself. Look up Joe Woodworker vacuum pump for inspiration. Not difficult, and with a good, cheapo pump from Ebay, it won't be very expensive either. I built a small one myself with pressure switch and reservoir.
- You can get OOA (Out Of Autoclave) pregpreg, where an autoclave is not required. But I would, as mentioned earlier, look into infusion. You get some nice benefits, dry lay up and as long a working time as you want to arrange the plies. You can debulk (pulling vacuum on the dry layers of CF to help them set properly) in between layups and when you are all happy with the layup, you bag and infuse. Less messy, more control, too. Last edited by Diving Gecko; 07-30-2017 at 01:08 AM. |
07-30-2017, 05:11 AM | #14 |
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Re: Pre Preg Carbon Wrap
Thanks all for the great advice. It was "Out of Autoclave", I was looking at. Very good video on You Tube by Easy Composites from U.K. showing Pre-Preg techniques.
Jon, if I get a chance I may drop by later today. It would be a sin to wrap one of your guns. They are at their pinnacle in design and appearance. |
07-30-2017, 05:26 AM | #15 |
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Re: Pre Preg Carbon Wrap
Spearq8, if you don't mind me asking, where did you get the vacuum tubes you are referring to. That's a great idea!
Kevin |
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