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 Post subject: Carbon / Graphite
PostPosted: July 5th, 2005, 8:40 pm 
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Joined: April 22nd, 2003, 8:26 pm
Posts: 805
Location: London, Ontario, Canada
Any carbon / graphite canoe builders out there?

Doug


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PostPosted: August 11th, 2005, 9:40 am 
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Joined: August 11th, 2005, 9:30 am
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Location: Barrie, Ontario
Sure, I've done a couple. Makes for very stiff and light boat, but can be a little fragile without some kevlar thrown in the mix. Vacuum bagging is very helpful here, since small voids can easily lead to large fractures with enough flexing.

Aaron


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PostPosted: August 11th, 2005, 12:22 pm 
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Joined: April 27th, 2003, 10:25 am
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aaronj Curious as to what sort of Vac system you've used for your boats?


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 Post subject:
PostPosted: August 11th, 2005, 5:45 pm 
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Joined: August 11th, 2005, 9:30 am
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Location: Barrie, Ontario
Standard vacuum bag technique.

Specifically: -laminate, coated peel ply, perf. release film, breather, vac bag.
Two vacuum ports in a pleat of bag at the center of the boat, roughly 29"HG of vac.

Had a little trouble with compression at the ends of the boat (a little too fine for the bag to apply good pressure) so next time I'll try making up some silicone intensifiers for the ends.

Also been toying with the idea of a bag side resin infusion, but that'll have to wait until there's a little more time.


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 Post subject:
PostPosted: August 11th, 2005, 5:54 pm 
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Adding a couple of vac lines to the shear at bow and stern may help with the compression problem you've experienced.

In the infusion work I've been involved with the vac lines are mostly along the flange/shear with the resin feeds along the center/keel line, right where your vac lines are.

What type of pump ?


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 Post subject:
PostPosted: August 11th, 2005, 7:23 pm 
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Joined: August 11th, 2005, 9:30 am
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Location: Barrie, Ontario
Actually, aIrflow in these areas wasn't a problem, I had my valves installed very near there, and they pulled in tight right away.
I think the problem was just surface area - if you saw the shape of this hull, you'd know what I mean, it's pretty fine at the keel line. Almost too fine, 'cause laying the fabric and avoiding bridging becomes a great pain.

Your infusion setup sounds pretty similar to a scrimp system; that was pretty much what I had in mind.

Vac pump is a Busch RC 021. Very pleased with it.

Aaron


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PostPosted: August 11th, 2005, 7:39 pm 
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Similar to Scrimp but we use specialty materials or a core that is high permeable rather than using the flow medium on top of the laminate stack and dealing with any patent hassle's (if they even still apply). This also negates the need of bleeders and release ply's, just peel ply on the stack and a bag on top of that.

Heard excellent reports on the Busch pumps, may look into one at some point. We are using Becker at the moment and have zero complaints.

Are you doing canoe or kayak hulls? Just curious as to the fine entry line.

What brand of bag do you use? I have found some similar problem to what you are indicating with some of the stiffer bagging materials. Despite it seeming quite tight the bag won't stretch and a small bridge can develop.

This is more apparent with infusion since the increased resin flow in any areas not fully compressed by the vac bag are quite obvious. Just a thought....


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 Post subject:
PostPosted: August 11th, 2005, 8:09 pm 
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Joined: August 11th, 2005, 9:30 am
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Location: Barrie, Ontario
For infusion I usually apply peel ply, non woven flow media, with any core either drilled, kerf cut, or both, with commecial wiring wrap (spiral tube) for vac lines at the perimeter.
Resin lines are either more spiral tube, an extra layer or two of flow media, or a silicone line made for the purpose, depending on the shape of the part and the resin involved. You're right though, I'm think many people have figured out ways around scrimp patents by now.

This particular hull was an assymetrical canoe, at the apex of the ends it is perhaps 3/4" across, so access is limited.

The bag was 2 mil nylon, which is nice and soft with our recent humidity, with rather large pleats into the corners. In fact, we actually blew the vacuum just after it was drawn and repositioned the bag just to ensure that bridging didn't occur.

It wasn't really too bad, and the bag was effective even in the corners. In the end I'm really quite pleased with how the boat came out.

My comment about an intensifier mainly had to do with convenience - it might save some the trouble next time. It is a trick that has worked for me before.

I've had good luck with Becker myself, by the way. Is yours portable, plummed in?


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 Post subject:
PostPosted: August 11th, 2005, 8:35 pm 
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Yes I've used the spiral wire wrap as well but found pvc pipe cut in half worked well for production feed lines and it is conformable to the hull shape if you heat it first.
This also allows the 1/2 pipe to be used a number of times while the spiral usually gets trashed in the process. We also waxed the pipe which helped a lot.

We've used a number of different cores. XTC dbl & trip cuts flow well or for long cures (over 1 hour) we have scored and drilled Kledgecell (?sp). The XTC Core Cell is by far the easier but after an hour of styrene it begins to decompose as you know.

Quote:
I've had good luck with Becker myself, by the way. Is yours portable, plummed in?
:lol:

Plummed in I'm afraid.... 10 hp, 120 cfm at 29.9 Hg. 3" vac lines, 600 gal vac tank and remote 4 station vac manifolds. It's HUGE !!!

I actually want to get into a small pump for repair work and some testing on canoe/kayak infusion work.


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 Post subject:
PostPosted: August 11th, 2005, 8:47 pm 
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Joined: August 11th, 2005, 9:30 am
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Location: Barrie, Ontario
Klegecell is available prescored....

The released half pipe is a good idea. I'll have to give that a try. I've had good luck with "Omega" shaped lines, which are reusable although they are quite expensive relative to a piece of plumbing pipe. Have you found any that are flexible but without collapsing when cut in half?

That's quite a vac system. The RC021 is a bit smaller - 15cfm, 29.9, 3/4"NPT inlet Mine came prewired with a 110V cord and and switch. Performs well though, small enough to be portable, and it runs very cool and quiet. It's nice when you can easily talk to other people in the shop while the pump's running nearby! FWIW, it gets thumbs up from me.


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 Post subject:
PostPosted: August 11th, 2005, 9:14 pm 
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Joined: April 27th, 2003, 10:25 am
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We added some flow scoring even to the prescored Kledg simply because of the size of the projects we were doing and the need to maximize flow through the laminate.

Have seen the Omega ramp but the cost was hard to justify considering the results we had with 1/2 pipe. Even fairly thin schedule 1/2 pipe will stand a lot of vac presure yet still is quite flexible when it is cut. Heating it to conform to the hull shape then holding it in place with strip of peel ply spray glued to keep it in place works great.

We also made our own Omega ramp this way. With peel ply in place and the 1/2 pipe conformed I would run spots of hot glue to hold then fillet with bondo. Do peel ply and a glass layer over this and you have a skeletal feed system that drops into the hull........ great for production runs. :lol:

We were doing VERY large pulls with the Becker, 2-3 45 gal drums of resin at a shot so we needed huge volume. It was a 3 phase 220 volt motor, oil flooded rotary vane.

I'll give the RC021 a look... thanks for the tip.


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