Newbie seeking advice for CF motorcycle parts!!

General Composites Discussions Composites Talk
#1

I am fairly new to working with CF, only about a year of limited experience. I have had some success making some parts, but I have a couple questions.

I am trying to make some frame guards for a motocross bike. In the picture is the two guards I would like to duplicate. I have used some epoxy to smooth out some of the aluminum welds. Should I use the aluminum as a mold, or are there better options? I made one CF guard using the aluminum as a mold, but had a problem with some air bubbles, and the finish was really dull. What can I do to remedy this?

On some of my other parts, I have just used a good carnuba wax and some hair spray as a release agent. Is that good enough?

I am using West Systems Epoxy, with the slow hardner.

Thanks in advance for all you help?

Coach

#2

Hey Coach,

You can use those aluminum pieces as mold but you’re going to end up with parts that are either bigger or smaller than the original depending on which side you lay it up on. If fitment is not an issue then you can certainly do that. The finish of the part directly reflects the finish of your mold. The shinier the aluminum, the shinier your final part.

This is the first time I’ve heard of someone using hair spray as release agent. But whatever works for you. My only worry there would be the possibility of the resin eating into the hair spray and become contaminated. That could also be why your parts are turning out dull. Try it next time without the hairspray and see if you get a different result. If your mold surface is smooth and non-porous then the wax alone will do.

Evan

#3

May I also suggest that you try vinyl ester resin. Epoxy is strong but it’ll break down over time under UV light. Our engine compartment parts are made with high temp epoxy resin and pretty much everything else is made with vinyl ester. Don’t use polyester with carbon.

#4

Thanks Evan.

You are looking at the back side of the guards, which I plan on laying the CF onto. That way the exposed surface when the guard is done will be nice and shiny I hope.

Any advice on the air bubbles?

The guy at West Systems suggested the hair spray when I was making a CF shock guard, and using the aluminum shock as a mold. Worked real well, but I will try using only wax once.

How are the fumes with vinyl ester resin? Does it hold up to abrasion as well as epoxy resin? Cost benefits?

Thanks alot,

Coach

#5

Well if you got that advice from WS then I wouldn’t worry about it. The fume on vinyl ester is considerably stronger than the West System epoxy. Good ventilation is called for. Acutally, that should be a requirement for all types of resin. I do a lot of closed mouldings so I don’t really have a problem with the fumes.

Vinyl ester is a form of epoxy, formulated to work like polyester. It’s much stronger than polyester and a little less than epoxy. You can get them for about $30-40/gal. A lot less than WS.

Now that I think about it you should stick to the WS epoxy. If you don’t vacuum bag your parts then you’re going to hate me for suggesting the vinyl ester. It’s very thin and is not sticky like the WS epoxy.