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Old 10-29-2014, 01:22 AM   #11
Jonty

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Hi chaps, I haven't got photos available just yet of my latest effort, but essentially the parts I made this weekend look very similar to the photos above; bridging is marginally improved but not eliminated, and the resin has still been pulled out of the laminate stack leaving the air between the weave.

Initially the double layer of breadwrap looked to be working, but actually it just slowed down the movement of resin into the breather, but did not prevent it; there was some pooling of resin in the breather towards the vacuum fitting.

I did one piece with a 200g twill at 0 deg, then 400g twill at 45 deg, and the other part was 200g 3 plys at 0, 45, 0 deg. they both look the same as each other and the same as before so unfortunately changing the orientation and using a heavier fabric hasn't helped - I think these ideas are not wrong, just I've got another more fundamental problem. With the consolidation I struggled to get the carbon to stay in place over the edges before bagging, and then even with only partial vacuum it was a real struggle to move the laminate into the corners using fingers or a nylon tool. Maybe this will come with practice? However the air between the weave seems directly linked to the resin being pulled out the back, and feels like a hardware/setup problem, not a technique issue.

Any suggestions for what direction I should head for the next parts?

Thanks!

Last edited by Jonty; 10-29-2014 at 01:28 AM.
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Old 10-29-2014, 04:34 AM   #12
AVT

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Perhaps you might try a simpler part first. Maybe something small and flat to get a handle on your air issues then move to the more complex part to deal with the bridging. That should separate the two major issues and make it slightly less complicated. (and cheaper)
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Old 10-29-2014, 04:50 AM   #13
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Hi AVT, thanks for the suggestion. I do have a flat panel I can use, and since I want some flat sheet for some other projects I could look at using this. However, the depth of this part is only about 1cm, and the mould shape is not too complex - essentially just 2 blisters standing out of a rectangle. It's about 30cm long and 12cm wide, so not that big - basically mixing the gelcoat in a smaller quantity is difficult as I am using less than 2g of MEKP anyway!

Do you think air between the weave is related to the the bridging? And if so what could the mechanism be? If the air between the weave is caused by the bridging I'll move to the flat panel again, otherwise my gut feel is to stick with the small mould since it at least gives me some practice at laiminating and consolidating.
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Old 10-29-2014, 05:17 AM   #14
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I didn't notice any discussion about how much vacuum your pulling?Maybe try dropping that and see?
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Old 10-29-2014, 05:35 AM   #15
Jonty

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Hi Mike, we're pulling about 28.5in. So you'd suggest we back it off? And if so, what would you aim for?
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Old 10-29-2014, 05:48 AM   #16
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I would drop that in half so less then 50% or even lower and see,maybe try using just fiberglass to keep costs down until you have it right.
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Old 10-29-2014, 05:52 AM   #17
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Ok thanks mate, I'll have a try at that for my next attempt... gel coat tomorrow and then laminate friday afternoon I think.
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Old 10-29-2014, 06:45 AM   #18
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You could also try letting your resin kick a little so it doesn't bleed so easy. What kind of perf release film are you using?P3?
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Old 10-29-2014, 07:19 AM   #19
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I'm using this from Easy composites. I just searched P3 film and came up with this from their store as well. This states ~8mm spacing for P3 - I'd guess the breadwrap is about twice that frequency.

One of my queries earlier in the thread was whether people think I should use a less perforated release film (or even non perforated) but unfortunately no one was able to offer any guidance. Have you got experience of 'breadwrap' or a similarly high perforation release film, or have you always used P3?

**EDIT**

I realised I had been speaking to Easy Composites about the mould release problem I was having previously, but hadn't called them about these issues; I just spoke to one of the guys who suggested dropping the vacuum down to "about 15-20%" so 4-6in for wet lay. He also said that the release film perforation won't make much difference - I could just get rid of it if I wanted, however I've found it makes removing the breather much easier, so it'll stay for now.

I think part of the problem with the bridging may be that I am going heavy with the resin and so this pools next to the surface and keeps the carbon away, then when I leave my pump on the resin is wicked away, leaving the bridged area as well as the air between the weave.

Soooo... my plan will be to go less resin rich, wind the pump right down to 5in, and have another try.

Last edited by Jonty; 10-29-2014 at 07:47 AM.
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Old 10-29-2014, 06:18 PM   #20
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I also use p3 seams to work. Not sure if you can get anything smaller or bigger spacing. I think the reduced vacuum alone will give you a better looking

What is bread wrap ?
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