New to the board! Some CF questions....

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#1

I’m looking at doing some CF parts for my motorcycle. Nothing structural, just dressup items really. I’ve been reading around and so far the best method I’ve come across is vaccum bagging using one of those space saver bags as they hold their vaccum pretty well. I have some and figured I would start from there.

I’ve already seen lots of things on layup and making fiberglass molds, what resin to use, etc. but there is one thing I’ve seen varying opinions on and would like a more definitive answer on.

One article basically did one layer at a time, meaning he’d vaccum bag and cure on layer of CF at a time. Seems rather time consuming to me. It seems like other people are just laying down their 5 or 6 sheets and vaccum bagging it straight up.

What is the consensus here?

#2

It would be better to bag all your layers at once, that way you have a good chemical bond between the layers, not a secondary bond. Unless your going to be doing very thick laminates, a one time bag is fine.

#3

That’s what I thought. I mean, I’m sure the resin can bond to the cured resin, but a straight up all layers at once would be the strongest bond.

Another question: how many layers? He was doing as much as 5 or 6, but I read elsewhere on this forum, where a guy was asking advice on his air intakes for his motorcycle, that 3 layers of ~6 oz. fabric, adding up to about 18 oz should be fine. That would make sense to me as well as it’s all dress up items and nothing structural. Although one of the items I want to do is heel plates and I guess my foot would be touching it all the time, so maybe 5 or 6 layers would be better to have a strong form?

#4

You said that your parts are not structural, so 5-6 layers of carbon may be a overkill. It really depends on the size and shape of your product, something that is small and has lots of shape to it will have better form strength so will need less layers. My suggestion is that you make some different test panels so you will get a better feel of the different combos of lamination. 5 layers of 3k carbon is equal to ~1mm. If you want to create a very stiff part, you are better off using a core to bulk up your thickness. also 6k, and 12k carbon are availible, these are good for building laminate thickness up quickly, and are more cost effective. Fiberglass can also help cut cost if your part does not require solid carbon in it.

#5

Thanks a lot for your responses, it’s good to get som direct answers rather than putting lots of different information together.

Another thing I noticed on this board was the resin to fiber ratio. I’ll definitely have to look at that more closely and get that down, but for now, I need another question cleared up.

One some videos/articles it says to lay your first layer of fiber down and then saturate it. On some other rescources, I see where they would lay down some epoxy first, then lay down the CF and saturate it with a brush/roller.

I would think laying the carbon down and then saturating it would help to more easily control the cloth/resin ratio, correct? But as I am leaving it raw, I’m tempted to throw down resin first to make sure I get a good finish on that side, you know? But then I also read that too much resin weakens to piece overall.

Suggestions?

#6

The proper hand lay up is to apply a gel or skin coat, let it B stage and then start laying in the reinforcements and wet out…let it late B stage and trim along the edge with a knife.

Molds are for making more than a few parts. Try overlaying if only doing some one offs.

Or make molds from Plaster of Paris, fully dry, seal / coat, let that fully dry and then wax before laying it up…

#7

Ok, gel coat, this is exactly the sort of thing I’m looking for.

I planned on using molds made from fiberglass to make several CF pieces using the same mold via vaccum bagging.

So should I lay down the gel coat and let it (you’re going to have to define this one for me) B stage and then lay down my 3 or so carbon layers wetting each one as I go, bag it up and let it cure?

And on gel coats, is there a specific one I should use depending upon the resin I go with? I plan on using West system resins. Do they make a gel coat specific to their own epoxy resins?

Thanks all for the great info so far.

#8

How do you seal your plaster molds? Ive tried many ways but Ive always ended up partially destroying the mold.

#9

Add shreded burlap into the P of P as a reinforcement. Or get Hydrocal or Ultracal which are US Gypsum products but much more durable. They even have some material that harden us that you can machine it after drying!

It must be 100% fully dry and then coat of clear spray paint or I even have used PVA first and then paint or whatever was handy…but again, it must be fully dry before waxing and laying it up!

Haste makes waste

Take a small amount of the resin you are going to use, catyalyst it, stir and watch it going thru the stages of liquid (A), starts the gel (B Stage) and fully click dry © stage.

Every beginner needs to do this, but rarely does.

Make small test panels first before wasting material on larger parts…

#10

So you’re saying that there is no “gel coat” as it were other than laying down some epoxy and letting it gel (stage B)?

I plan on starting small with some heel guards for the bike. Those are very small pieces and will be good practice for me.

thanks for the info.

#11

For regular wet lay-up vacuum bagging your best to spray your clear gelcoat, let tack off completely if your going to use epoxy. Lightly wet the gelcoat with a thin film of epoxy, lay your first layer down carefully. Wet out your fabric with a 3" cheap brush. you should only use enough resin to get the fabric wet, do not over saturate, there should be no puddles of resin ever, and the carbon shouldnt be floating. put all your layers down this way. Peelply next, then bleeder, 7-10oz breather. then vacuum bag your part. depending on your resin system your using, the time you spend on laminating and other factors your part should end up with a resin contenty between ~30%-40%.