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Old Jan 05, 2009, 11:56 AM
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Originally Posted by LesUyeda
Surfboards

Les
There's a reason the surfboard folk are called "resin-heads" -Dude, that's like.... Dude. wha-a- ... Dude. Cool.-
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Old Jan 05, 2009, 01:07 PM
Shedofdread is offline
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Used to use polyester for thermal and slope fuselages. They can be made very strong. But epoxy is stronger. Better strength to weight ratio, less shrinkage and more stable.

True the smell is awful but it is easier to use. Moulds can be made real quick with CSM (chopped strand mat). Still use it for slope stuff where the last ounce of performance isn't neccesary.

S
Old Jan 05, 2009, 01:53 PM
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To keep the cost down and quality high go with West Systems Epoxy. Here's a good link for it: http://www.aircraftspruce.com/menus/...stsystems.html

You can buy one base resin (105) and get different hardeners to your liking (5 min, 30 min, etc.). The best hardener for lamination work is the 206. Also, get the auto ratio pumps. No guessing on how much of each component to use. I was fortunate and had 3 gallons given to be a couple years ago. It will keep very well if you keep it cool and out of the light.
Old Jan 05, 2009, 04:31 PM
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I have never used polyester resin in aircraft applications etc... I have used the nasty stuff to make moulds (because epoxy/urethane moulds would cost alot!). Tooling gel, resin, and glass cloth work well.
I get Westsystems epoxy for $55/L and use that and 10/30min epoxy for everything in an airframe, composite part etc..
Old Jan 05, 2009, 07:27 PM
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I've used polyester resin with no problems. You can't apply it over foam as has been mentioned as it melts the foam and you have to be careful of the shape of male molds as it does shrink a tad. Shallow male molds are o.k. but deep male molds are a no-no as the polyester resin will shrink on the mold and lock it tight to the mold. Ask me how I know.

Planeman
Old Jan 06, 2009, 07:16 AM
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Cost and smell are the major differences. Somebody has already said: The fiberglass is where the strength comes from, the resin less so. 20 years ago many people used Fiberglass cloth and polyester resin to finish airplanes. The Gougeon Brothers and their West Systems method of finishing have brought epoxy to the forefront, today. One of my first power planes was finished with polyester resin only, no cloth. This method was outlined in RCM's Flight Training Course and it worked fine. My wife was not happy with me; however, simply becase of the very strong smell. I would use epoxy now, using either System Three or West Systems products. Polyester is still used in the boat building industries, due to costs; but, epoxy is making in-roads there also. Remember, Polyester doesn't want to cure over epoxy. The other way around is o.k.
Old Jan 06, 2009, 08:30 PM
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It should also be mentioned that the "polyester resins are easier to work with than epoxy resins" mode of thought- while once VERY true, is far far less so today. The main problem epoxy resins had was cure times (and sometimes wouldn't cure) in temps outside their range. They've improved SO MUCH.

West Systems is the classic- also look out for MAS epoxies, kayak homebuilders really love the stuff.
Old Jan 12, 2009, 08:44 AM
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Quote:
Originally Posted by guinnb
To keep the cost down and quality high go with West Systems Epoxy. Here's a good link for it: http://www.aircraftspruce.com/menus/...stsystems.html

You can buy one base resin (105) and get different hardeners to your liking (5 min, 30 min, etc.). The best hardener for lamination work is the 206. Also, get the auto ratio pumps. No guessing on how much of each component to use. I was fortunate and had 3 gallons given to be a couple years ago. It will keep very well if you keep it cool and out of the light.
Ding, ding, ding, we have a winner. I have used West Systems and it is super stuff. The auto ratio pumps make it super easy and minimize waste. West Marine also carries West Systems:

http://www.westmarine.com/webapp/wcs...imary%20Search

Also the West Systems is about odorless. If your workshop is in your house the smell of the polyester resin will permeate every square inch of your home and it isn't pleasant. Go with epoxy if only for that reason.
Old Jan 12, 2009, 09:30 AM
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What is the typical West Systems product you guys use? I noticed a "G-Flex" that seems like it would be pretty good for planes, but not being that up on epoxy I'm going to bow to the experts. It will be used for GF on wings and CF on spars.

Keith
Old Jan 12, 2009, 10:41 AM
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Quote:
Originally Posted by kwmtrubrit
What is the typical West Systems product you guys use? I noticed a "G-Flex" that seems like it would be pretty good for planes, but not being that up on epoxy I'm going to bow to the experts. It will be used for GF on wings and CF on spars.
Keith
I am not familiar with the "G-Flex" but it would appear to be a 2 part epoxy for fastening parts, not a resin to wet out cloth like the 105 resin.
Old Jan 12, 2009, 02:58 PM
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In a related question, what types of epoxy are there? Can the West Systems epoxy be used for all applications or it is more for laminating type applications? Can/should it be used for applications that would require more strength like bonding wing tubes and such or would some other 2 part epoxy be better for that application?

~Dan
Old Jan 12, 2009, 04:43 PM
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Quote:
Originally Posted by Ninjak2k
In a related question, what types of epoxy are there? Can the West Systems epoxy be used for all applications or it is more for laminating type applications? Can/should it be used for applications that would require more strength like bonding wing tubes and such or would some other 2 part epoxy be better for that application?

~Dan
Here is a link for West Systems epoxy. Maybe they can answer your questions.

http://www.westsystem.com/ss/
Old Jan 12, 2009, 08:40 PM
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G-flex is a VERY flexible epoxy. YOu can bend a layup 180 degrees without breaking or cracking. Not for stiffness. And it can be mixed with 105 system to get intermediate characteristics.

And BTW the smell of polyester resin is not the polyester. It is the styrene monomer solvent The styrene thins the mix and also reacts to be part of it.
Old Jan 12, 2009, 08:54 PM
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Originally Posted by Pinecone
And BTW the smell of polyester resin is not the polyester. It is the styrene monomer solvent The styrene thins the mix and also reacts to be part of it.
Whatever it is I don't think you want to do any in your basement workshop.


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