Making a carbon fiber fender

J-Rod10

Active Member
DTT BOTM WINNER
If it hasn't been opened, you're most likely fine.

If it has started to go bad, it'll be chunky.
 

billyp

New Member
It hasn't been opened until last night...it wasn't chunky

One other question, it's a little chilly right now, 50-60 in the garage, should I just let the gel coat cure on it's own or help it with a little direct heat? Not blast it with a heat gun, just place a small heater nearby. Is it better to let it flash on it's own to work it's chemical magic?
 

J-Rod10

Active Member
DTT BOTM WINNER
I let it flash by itself. It just takes longer. I typically let it sit overnight. That will minimize your chance for shrinkage once you start laying it out.
 

billyp

New Member
J-Rod10 said:
I let it flash by itself. It just takes longer. I typically let it sit overnight. That will minimize your chance for shrinkage once you start laying it out.
As long as it flashes eventually I'm cool with waiting. This whole thing is definitely not something to be rushed if I want a decent product, figured that out already
 

billyp

New Member
Finally making some progress. Sprayed on a couple layers of PVA



After PVA set, mixed up and brushed on the first layer of gelcoat



Looks like a lot of brush strokes on the outer surface, but with everything I've seen and read, the actual surface of the mold where the gel contacts the plug will be nice and smooth.....I hope ???
 

billyp

New Member
Made some flock or milled fiber filler out of scrap pieces of fiberglass using a cutting wheel.



Mixed it with some resin and made a paste to fill where the side of the plug meets the board



Next I laid some veil fabric as a first layer. Chose this method just in case my brushed gelcoat was a little thin in some areas with the hope the veil will give a little stability for the following layers of chopped strand mat.



 

billyp

New Member
Two layers of 1.5 oz mat







Of course the biggest event is still to come, seeing if the mold releases, but for my first time, so far everything is going very smoothly.
 

billyp

New Member
Last 2 layers, 2 oz mat



How long should I wait to pop the mold? I'm in no hurry and have heard everything from 24hrs to a week
 

Sonreir

Oregon
DTT SUPPORTER
It can depend on the temperature and humidity.

Drier and hotter will make it cure faster.

Indoors at room temp will usually be good in 24 hours, but if you're not in a hurry give it two days.
 

J-Rod10

Active Member
DTT BOTM WINNER
billyp said:
Last 2 layers, 2 oz mat



How long should I wait to pop the mold? I'm in no hurry and have heard everything from 24hrs to a week
I usually pop them in 24 hours. Touch it. If it's still tacky, let it sit another day, if not, pop it off.
 

billyp

New Member
Working late the next few days, I may try popping it off tonight.

As far as prepping the mold. I know I'll have to sand it down, should I start at 400 wet or something lower? Take it up to 12 or 1500 wet? Can I hand buff it with polish or do I need to use a buffer?
 

billyp

New Member
Found some time to pop the mold off. It easily came off of the board, I barely had to pry on it, but the actual plug was a different story. I think because of the straightish sides, and the fact it was only hot glued in a couple spots, it got stuck in the mold, I had to destroy the plug to get it out. If I do a fender again I think I'll put a flange on the bottom of the plug so I can lever it out of the mold easily.

Remnants of a once nice plug



It's not perfect, but for my first time I'm very happy with how it turned out. It's plenty good for a one time use mold. So far I've only sanded it with 220 and 320, the wet sand to 1200 is still to come



 

billyp

New Member
Started getting ready to lay up the carbon fiber in the mold.

First I made a rough pattern by putting tape down on the mold, pulled it out and and got it semi flattened out.



With the tape pattern I was able to transfer the size to poster board and cut out a pattern for the carbon fiber and the vacuum bagging consumables.



Got the carbon cut to size along with the breather cloth, peel ply, and release film. I'm doing 5 layers of carbon and I cut the pieces so the layers will be laid out 45,0,45,0,45.





Next I set up the vacuum bag. I'm going to use it like a big envelope, leaving plenty of slack in the bag so it will be able to get down tight in the mold when the vacuum is pulled



I duct taped the edges and corners so it won't accidently tear the bag



I found out about Frekote from some composite forums and R/C model building videos online. It's a one step release agent, no wax is needed, just the spray



Set the mold in a makeshift stand so it won't roll around on me




Here goes nothing!
 

billyp

New Member
Just realized I never showed a finished fender



The Freekote worked great, popped right out



Got a couple of voids, I assume I can just fill with resin and sand down?







Next I'll trim it down and put a couple coats of resin on to fill and even everything out.

Overall I'm happy with my first attempt at carbon fiber and vacuum bagging. Would rolling it out or using a plastic body filler paddle thing to press it into the mold help With those voids?
 

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