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Fiberglass Thickness

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Postby expfcwintergreen » Tue Oct 12, 2004 10:16 am

Simple question, although I suspect the answer may not be...

Is there a rule of thumb regarding epoxy layup thickness (i.e. "x" layers of "y" oz cloth gives you "z", etc...)? I know there is a thickness spec on the dry cloth, but what is the typical additive effect from the resin?

Chris
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Postby ThorDesign » Tue Oct 12, 2004 12:22 pm

:o
Last edited by ThorDesign on Thu Feb 28, 2008 5:44 pm, edited 1 time in total.
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Postby oracle_9 » Mon Jan 15, 2007 11:02 am

thor,

1) How rigid is that layup? I mean is it firm on when you press it or you can squeeze it?

2) Also, by any chance you know what the weight of this FB layout for the seawolf hull was?

3) What epoxy did you use? I only have NHP 30 min., and Z-Poxy Laminating. Any of these suffice? or any recommendations?
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Postby expfcwintergreen » Mon Jan 15, 2007 11:28 am

Matt typically doesn't frequent this board these days, but I do have two of his kits and they are pretty solid. Yes, they can be deflected, but most shapes with a thin cross section can be if you apply enough force.

If you need something extremely rigid, the addition of stiffening ribs helps, the number and geometry of which would be based on how much force you would want to resist (just like the real boats!).

As far as epoxy goes, use something that has a cure time greater than 1 hour, preferably two. Quick-cure epoxies are not waterproof. Many of us use the West Systems brand.
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Postby Pirate » Tue Jan 16, 2007 12:08 am

I use Fibre Glast's System 2000 Epoxy and hardener. Very good stuff, and with 1- to 2-hour catalyst, very easy to work with. Very reliable shipping.

http://www.fibreglast.com

Pete
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Postby Albion » Tue Jan 16, 2007 3:13 am

ThorDesign wrote:Chris,

My standard layup in epoxy for a Seawolf hull is 1-2 0z., 2-4 oz. 2-6 oz, and one final layer of 10 oz. Weigh the cut cloth out. Whatever the weight is, that is approximately the amount of resin you will need. If you have more than 50% resin by weight your layup will be somewhat more brittle. The above layup provides a all up laminate thickness of about .080" which is just about right for a model of around 48" long. For the permit, I use one less 4 oz. layer.

Good data thanks
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Postby Sub culture » Tue Jan 16, 2007 12:46 pm

For polyester lay-ups, I use the following-

Coat of gelcoat, then two layers of 300 gram CSM with layup resin, with a little extra reinforcement in critical areas and rovings in areas with sharp corners etc.

I've been recommended to use surface tissue before laying on the CSM, and I may try this on my next lay-up, although I have found the CSM and gelcoat satisfactory so far.

Suitable for boats upto about four feet. You may want to add another layer of 300 gram for larger boats.

I prefer lots of layers to using thick matt, as it conforms easier to the mould.

I give epoxy a wide berth, as it costs a small fortune here in the UK. West Systems is about five times the price of polyester! :shock:

Andy
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Postby oracle_9 » Thu Jan 18, 2007 5:54 pm

what is "CSM" ?
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Postby dietzer » Thu Jan 18, 2007 11:12 pm

CSM stands for "Chopped Strand Mat". It is basically a thicker fiberglass cloth made out of chopped strands of fiberglass, hence the name.

Hope this helps,

Carl
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Postby oracle_9 » Fri Jan 19, 2007 12:01 am

Oh, thanks for clearing that up.

Is there any difference between the chopped and regular cloth of Fibreglass?
Does this chopped type offer more rigidity or doesnt matter?
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Postby Sub culture » Sun Jan 28, 2007 10:36 am

Woven cloth is stronger than CSM, but doesn't tend to conform to the mould as easily.

CSM is more than strong enough for model submarine use. Woven cloth however can result in a thinner and lighter lay-up, which can pay dividends when calculating the size of your ballast tank if you're making a wet hull boat.

I use CSM.

Andy
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Re:

Postby modelnut » Sun Aug 01, 2010 11:26 am

Albion wrote:
ThorDesign wrote:Chris,

My standard layup in epoxy for a Seawolf hull is 1-2 0z., 2-4 oz. 2-6 oz, and one final layer of 10 oz. Weigh the cut cloth out. Whatever the weight is, that is approximately the amount of resin you will need. If you have more than 50% resin by weight your layup will be somewhat more brittle. The above layup provides a all up laminate thickness of about .080" which is just about right for a model of around 48" long. For the permit, I use one less 4 oz. layer.

Good data thanks


I understood maybe one word out of three. :oops:

I think he said one layer of 2oz cloth, two layers of 6oz and a final layer of 10oz. Is that right? For a boat that may end up between 40 and 50 inches that sounds like a lot of cloth.

- Leelan
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Re: Fiberglass Thickness

Postby Thor » Mon Aug 02, 2010 2:11 pm

That really is not a lot of cloth. Most layups are over 1/8" thick or more. If done in the right combination ,without resin oozing out of the weave, this will give you a nice, solid, laminate without excessive weight and outstanding durability. If you go less, you will find you may have excessive deflection of the hull.


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Re: Fiberglass Thickness

Postby modelnut » Fri Jul 01, 2011 4:41 pm

If you are not laying up fiberglass in a mold wouldn't you layer cloth in reverse order? Say you are making a one-off hull. Would you go one layer of 10 oz, two of 6 oz, two 4 oz and one 2 oz? :?

I'm just thinking that the outer most layer should be the most supple.

I've changed my mind about building plank-on-frame. Going back to a shaped foam hull.

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Re: Fiberglass Thickness

Postby Thor » Fri Jul 01, 2011 7:04 pm

Keep the lighter layers on the outside, but only apply them after you have sanded the course stuff down smooth.
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