Re: Which Epoxy System is best?


Allan Farr
 

Hi. Thanks for the reply/info. I don't consider myself the designer, just the builder (of the last 10%). I suspect that amateur experimentation (by me) is unlikely to provide a more reliable answer to my question than just asking various knowledgeable people (some of which are in this group?) Ideally I would like to use EZ-Poxy because as you said it is as close to the original as you can get, unfortunately in these parts (NZ) it's hard to get hold of.
Regards
Allan

----- Original Message -----
From: oneskydog@...
To: Q-LIST@...
Sent: Wednesday, November 26, 2008 2:08 PM
Subject: Re: [Q-LIST] Re: Which Epoxy System is best?


Allan,

First of all you are the designer and it is your responsibility to determine
if the structure you are building is adequate for the task. What we are
talking here is material substitution for a proven material that is no longer
available. How you get your design numbers is up to you or if you want just grab
a can off the shelf based on my opinion of someone else's opinion that is up
to you.

Composites are not like aluminum where you go to a handbook and find design
data, do your calculations, and go build a part of known strength and
stiffness.

With composites you are the basic material manufacturer from which you build
your structure. Several things affect the properties fiber type, resin type,
fiber to resin ratio, degree of compaction, void content, manufacturing
processes, ect. There is no material data handbook. Manufacturers build and test
to get data to design to and they do not share. If you want to know how
strong or how much heat your structure can take you have to build and test.

What I said is that the heat distortion temperature of Aeropoxy PR2032 is
higher than ProSet. That does not mean it is better for your parts you design
and build with assistance from unsupported obsolete plans.

I talked to an old epoxy formulator at a trade show and he told me that
EZ-Poxy is the same thing as Safe-T-Poxy just renamed. Hexcel dropped it like a
hot potato when the MDA flap was in the news. If you use good practices and do
not cook the cure agent or eat it you will be just fine.

EZ-Poxy would be as close to the original design as you can get.

This Internet dribble is worth what you paid for it. If you really want to
know do some hard work and test it you will know for sure what you can build.
You are not building a QAC Q-200!!! You are the designer and builder it is
awesome responsibility you are building an Allan Q-200 for education and
recreation. At the end of the day you will get in it and bet your life you made the
right decisions on much more than what kind of epoxy to use.

I hope this is helpful for you to make your decision. Please do not pit my
opinion off against someone else's. Do your own research. This is not
research. Data sheets can help but they do not tell you how they came up with the
numbers. Testing pure epoxy does not tell you much about your structures because
that is only part of the composite material. Tests with high numbers
indicate unidirectional fiber reinforcement in the test coupon.

Regards,

One Sky Dog



In a message dated 11/25/2008 5:02:19 P.M. Mountain Standard Time,
sam.hoskins@... writes:

Without current test data at hand, it's hard to tell. If you want to do the
research, look at the data sheets for all the epoxies and compare the
numbers. Compare apples to apples.

In my post below, the second paragraph is a quote from Mike Bergen.

Like I said, I am currently using ProSet for structural and West for
finishing.

Sam Hoskins
Murphysboro, IL
www.samhoskins.www.samhowww

On Tue, Nov 25, 2008 at 5:54 PM, Allan Farr <_afarr@...
(mailto:afarr@...) > wrote:

> Hi. So in your opinion West System is ok? One Skydog said the opposite -
> I'm confused;(
> Regards
> Allan
>

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