Making a carbon fiber fender

billyp

New Member
Never done any carbon fiber work, and have very limited experience with fiberglass, but I thought I would give making a fender a shot. I've never made a mold, but from reading up on topics here and on the interwebs, I think I've got a basic grasp of how to do it. My whole build has been a learning process and I like learning new skills and how to do things.

I started with the stock front fender off of my XS650, taped it up and laid a couple layers of glass to get a general shape.





Popped the fiberglass off the fender, cut it to the shape I wanted and started filling and sanding





Got the body work done and coated the fender with multiple coats of primer





Since I put the primer on pretty heavy, I'm going to let it cure for about a day and a half. Once it's good and dry I'll do some wet sanding then put on a coat or two of Aqua Resin (thanks Deviant) wet sand, polish, then start the mold making process. More to follow
 

J-Rod10

Active Member
DTT BOTM WINNER
If you are making your mold off of that. You can either wax it very well, or, personally, I use PVA, spray it, then spray your tooling gel. Let the gel cure for a hour or two, and lay your glass on it.

Carbon isn't too bad. You'll want a roller to make sure it is fully saturated and all of the air is out of it if you are hand laying.

These were hand laid.



 

billyp

New Member
So just wet sand the primer and wax or PVA?? I was going to wet sand primer to about 800 then coat with Aqua Resin and finish to 1200 or so.

Don't have the stuff to spray the gelcoat so I'm going to brush it on.

I picked up some vacuum bag supplies from ACP when I ordered the carbon, I want to learn how to do that too, so I'll be bagging the fender.

Those seats look awesome! I may be picking one up for my wife's CB360 in the near future
 

J-Rod10

Active Member
DTT BOTM WINNER
Bagging it is going to make it considerably easier.

Sand the primer down to 1000-1200, and gel it. I've never brushed gel coat, so I can't comment on that aspect of it. But, you're going to have a non-uniform thickness. I would let it sit for a day or two before I overlaid it with glass. If it is not thick enough, it will wrinkle when glass is put on it. You more or less eliminate that when you allow the gel to fully cure.
 

billyp

New Member
Copy J-Rod, you saved me a step and some time! As always, some good advice...

When I get ready to brush the gel coat on is it wax then pva or pva then wax?
 

billyp

New Member
I finally got the plug finished up. I did use the Aqua Resin, mainly because I had it, and this being my first mold making attempt, is a learning process, I want to try different things to find out what works for me and what doesn't. The Aqua Resin ended up working very well, I ended up mixing it a little on the thicker side, made it easier to get a thick coat while brushing it on, and all of the brush marks sanded down very easily. The stuff is great to work with, water based so it cleans up with water, wash the brush after each coat and you're ready to use it again, it has absolutely NO odor so you can do it in the house and not worry about stinking it up. The only issue I had was with bubbles, might have been from mixing or from my vigorous brushing technique. Because the bubbles turned into pin holes, I had to take some glazing putty to a few areas of the plug. After I did that and got it all sanded down, I hit it with a couple coats of primer to cover the putty, then sanded the whole thing down to 1500.





Going to get some sign board to attach to the bottom of the plug so I can have a flange around the mold, then start on the mold making process.
More to come
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Looks really awesome. As far as the bubbles, it is because of how it's mixed. Anytime you fold the material, you're introducing air. It's particularly difficult to keep the bubbles out with lesser quantities. Not applicable here, but when pour casting that stuff into a mold, you can hit the bottom of the table with a sander to vibrate the bubbles up to the surface. In any case, spritzing the surface with a solution of water and isopropyl alcohol will release the surface tension and pop the bubbles as long as its still in it's thixotropic stage.
 

billyp

New Member
deviant said:
Looks really awesome. As far as the bubbles, it is because of how it's mixed. Anytime you fold the material, you're introducing air. It's particularly difficult to keep the bubbles out with lesser quantities. Not applicable here, but when pour casting that stuff into a mold, you can hit the bottom of the table with a sander to vibrate the bubbles up to the surface. In any case, spritzing the surface with a solution of water and isopropyl alcohol will release the surface tension and pop the bubbles as long as its still in it's thixotropic stage.
 

billyp

New Member
Nj732port said:
have you made one yet?!
Not yet, Super bowl party yesterday. Got the last coat of wax on and buffed off. After work tonight I plan to get the first layer of gel coat on, maybe the second if I have enough time, then some chopped strand mat then hopefully pop the finished mold. Probably won't get to the actual carbon work until Friday, I want a whole day off to work on it so it's not rushed and I can get the whole vacuum bagging thing worked out.
 

J-Rod10

Active Member
DTT BOTM WINNER
billyp said:
Not yet, Super bowl party yesterday. Got the last coat of wax on and buffed off. After work tonight I plan to get the first layer of gel coat on, maybe the second if I have enough time, then some chopped strand mat then hopefully pop the finished mold. Probably won't get to the actual carbon work until Friday, I want a whole day off to work on it so it's not rushed and I can get the whole vacuum bagging thing worked out.
Very careful with the gel. It is finicky. You have a min thickness you want to be over, and a max a few mils away that you want to be under. Too thick, it gets too hot, distorts/cracks. Too thin, it wrinkles when the glass is laid.
 

billyp

New Member
I will definitely take my time J-Rod. I actually picked up a wet film thickness gauge to help make sure I don't get it too thin or thick so that should help. I also plan on doing the gel in 2 coats since I'll be brushing it on so that will help me not to get it too thick

I was also considering laying a surfacing veil as the first layer on the gel, then letting that set up before laying the csm...thoughts??
 

J-Rod10

Active Member
DTT BOTM WINNER
It could be done. I never do it.

May not be a bad idea with brushing the gel.
 

billyp

New Member
Put some clay in the seam between signboard and fender, last layer of wax done. Next up, gel coat

 

billyp

New Member
So I was about to start mixing up the gel coat and I noticed on the can it says it only has a 3 month shelf life from the time of purchase, I bought it about 6 months ago. I've never heard of this, but I have no experience with gel coat so I have no idea if this is true, but I'm not going to take any chances. On hold till I can get some new gel coat
 

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