Jeffco and Ratio tolerances

Submitted by Anonymous on

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From: Marvin Kaye <74740.231 [at] compuserve.com>
Sender: Marvin Kaye <74740.231 [at] compuserve.com>
Subject: Jeffco and Ratio tolerances
Date: Wed, 9 Dec 1998 19:43:02 -0500
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From:  pine [at] CPro.co.za >INTERNET:pine [at] CPro.co.za

Subj:  Jeffco and Ratio tolerances



Hi



Does anyone knows what the max tolerance for the ratio is.



I'm getting 6.2 grams hardner for 25.6 grams resin.



Thanks

--

Pine Pienaar

pine [at] cpro.co.za

Lancair 360 #664

Jeffco and Ratio tolerances

Submitted by Anonymous on

From: Bill Gradwohl <Bill [at] YCC.COM>
Subject: Jeffco and Ratio tolerances
Date: Thu, 10 Dec 1998 09:10:07 -0600
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Here's the arithmetic for getting ratio by weight for the standard Jeffco epoxy.



resin=9.5lbs/gal

hardener=9.0lbs/gal



Volume ratio is 1H:4R ie 1Quart Hardener:1Gallon (4 quarts) Resin or .25H:1R



(9.0/4)H:9.5R



2.25H:9.5R = 1H:4.223R

For every 1 part Hardener add 4.223 parts Resin by weight.

Total weight is therefore 5.223 for every 1 part Hardener.



Measure hardener.

Multiply by 5.223

Add resin till you hit that number.









Bill Gradwohl

IV-P Builder

N858B

Jeffco and Ratio tolerances

Submitted by Anonymous on

From: Marvin Kaye <74740.231 [at] compuserve.com>
Sender: Marvin Kaye <74740.231 [at] compuserve.com>
Subject: Jeffco and Ratio tolerances
Date: Thu, 10 Dec 1998 20:13:22 -0500
To: Lancair Mail List <lancair.list [at] olsusa.com>
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Posted for Guy Buchanan <bnn [at] abac.com>

Subject: Jeffco and Ratio tolerances



Pine,



If you can't get a reply from Jeffco (619-576-9900), I have some basic

information. The Jeffco's "Lancair" system uses its 3102

hardener, which is listed as an aliphatic mannich base hardener. In

general aliphatic hardeners are cross-linking and rely on a

"stoichiometric" mixing ration. Thus, if you supply only 78% of

the hardener required, you will cure only 78% of the available resin.

This sounds worse than it is, because a gross estimate of E/epoxy

bidirectional laminate properties indicates that the bulk properties go

as follows:



Modulus ~ -5% (4.44 Msi to 4.23 Msi)

First ply failure ~ -9% (18.4 ksi to 16.7 ksi)

Ultimate ~ -3% (72.5 ksi to 70 ksi)



Please note that compression properties are notoriously sensitive to resin

stiffness, and my software does not recognize that fact so you could end up

with greater reductions in compression strengths than those noted above.





Respectfully,



Guy Buchanan

Buchanan & Newcomer

********************************

NEW EMAIL ADDRESS: bnn [at] abac.com

********************************

Jeffco and Ratio tolerances

Submitted by Anonymous on

From: Marvin Kaye <74740.231 [at] compuserve.com>
Sender: Marvin Kaye <74740.231 [at] compuserve.com>
Subject: Re: Jeffco and Ratio tolerances
Date: Thu, 10 Dec 1998 20:48:25 -0500
To: Lancair Mail List <lancair.list [at] olsusa.com>
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Posted for "DON & PAT RYAN" <djpryan [at] ruralnet.net>



The WEIGHT Ratio is very important to hold as closely as possible.  I

believe the wt. ratio given is 10 g of Epoxy to 2.5 to 2.6 grams of

Hardener.  These materials react molecule to molecule and any mismatch will

result in some loss of strength.  The loss is least on the side of

excessive

hardner.  I haven't measure cured properties on this particular resin

system, but on a similar one I believe the deteriation in strength was very

noticable outside a +5%-3% of hardener.