Potential newb question - epoxy vs polyester

[kyle]

I plan on making a few carbon fiber parts for my dirt bike and mates bikes(without breaking the bank!) and up until today always thought using epoxy resin was the way to go. However, after speaking to a boat building place, the helpful guy I spoke to said I could use polyester resin.

Since doing some cost calculations it seems like epoxy won’t make me any money when I sell the finished parts to mates.

After the information I read on the internet, I thought that polyester resins crack when hit by rocks/stones/riders boots? Or does that just happen to inappropriate (for the task) resin? I’m sure I also read that epoxy has a stronger bond with carbon fabric.

Naturally I don’t want to make substandard products, so am cautious about using polyester resin. But at the same time, don’t want to make this little project cost ineffective.

Any help is appreciated.

Many thanks,

Kyle.

[kmt63]

i would never use polyester resin with carbon fiber.just get some lower cost epoxy resin.

[2talljohn]

^ Itried that before and lower cost resins just dont hold up to heat well if you want asthetically good looking parts.

I’ve always gone back to polyester since I cant afford to make a full switch to epoxy right now. And IMO polyester works just fine with carbon fiber, and I’ve herd that from dozens of others. Some say polyester should not be used with carbon fiber, but its a misconception. I’ve made dozens of parts with polyester and carbon fiber and have had no problems.

Well, I’ve had problems, but learned that those problems werent the resins fault, but were my fault.

Fiberglasssupply.com (I think thats it)

They sell good PE infusion resin if you want to go that rout.

Hope this helps :). Its worth a try before going to epoxy. Epoxy is just more difficult and overkill depending on what you are making IMO.

[susho]

Epoxy is just more difficult and overkill depending on what you are making IMO.

Then you shouln’t use carbon fibre either

Polyester will work with carbon, but it is more brittle, and will fail earlier than the carbon fibre does. So it is structuraly useless to use those two together. Use epoxy with carbon, or use black fibreglass with polyester resin. That way you use the materials best.

Since doing some cost calculations it seems like epoxy won’t make me any money when I sell the finished parts to mates.

Carbon fibre is expensive, you can’t afford to make good parts, just build cheaper ones out of (black)glass. By using carbon with polyester, you will get expensive parts wich aren’t much better than glass parts, and not as good by far as epoxy/carbon products.

[canyon]

Then you shouln’t use carbon fibre either

Polyester will work with carbon, but it is more brittle, and will fail earlier than the carbon fibre does. So it is structuraly useless to use those two together. Use epoxy with carbon, or use black fibreglass with polyester resin. That way you use the materials best.

Carbon fibre is expensive, you can’t afford to make good parts, just build cheaper ones out of (black)glass. By using carbon with polyester, you will get expensive parts wich aren’t much better than glass parts, and not as good by far as epoxy/carbon products.

This exactly.
Carbon fiber is a high strength material but high cost material. If you’re worried about cost switch to glass with one layer CF for looks.
The reason it’s inadvisable to use polyester with carbon fiber is that when CF is produced it’s 95 percent of the time made to bond with epoxy as best as possible. Polyester won’t so an impact or two could easily break your part.

[kmt63]

if you have ever felt the difference in a polyester carbon part.compared to a good quality epoxy part.you would know why i say never use the polyester.they are flimsy like cheep ebay honda parts.