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Making a Carbon tail section: two-part mold

45K views 40 replies 24 participants last post by  91zx6rFighter 
#1 ·
Hey everybody!
I think some of you may have read the Tank wrap thread, and since that isnt finished.. i thought that i would start another thread. :thumbsup:

I am waiting to do all the final sanding at the end.

anyway, this thread is about making an actual carbon fiber part. a complex one. I am making the tail section on my bike. I already made the tail in Steel and bondo... but as it isnt very resilient, too angular and REALLY heavy... i want to replace it with Carbon. so... the first thing to do is make a mold. the problem is that it has to be removable.. so. it has to be made in two parts.

That is what this thread is about.. so if you are looking for hookers and blow... well.... ;)

Anyway,

First, i got the tail section sanded smooth and then polished it. You want this original part to be as perfect as possible. I am going to have to do body work to the mold but you dont want to HAVE to even touch the mold.


Then, i made a splitter-plate template.


Transferred it over to masonite, and i used some thin plastic on the side that the fiberglass would be on so it wouldnt stick


I used bondo to hold it in place, but on top of tape so i didnt damage the other side. You need to protect the other side like your beer at a concert. NOTHING TOUCHES IT BUT YOU. protect it.


I used a razor blade to trim any bondo that had squished out under the board so that i had a clean flat surface, and then filled any gaps the bondo might have left with clay.


Then, i figured out what shape of cloth i was going to need and cut out all my layers. One light layer to go on first, three medium layers and then one heavy layer.


I got all my resin stuff ready to lay-up


Then, i mixed my resin and brushed it on the whole part. I did this with the bike on its side for ease of spreading and so that gravity would be working with me. i KNEW that physics class would come in handy one day.


the first layer of glass goes on. the fewer bubbles you get in it the better. this is going to be the surface of the mold. take your time to get it right.


And..... here we have the first side laid up


I removed the splitter-plate and the tape. make sure that the surface is clean and ready and then wax and release the remaining side and the flange surface.


Second side is laid up exactly the same way as the first


Now i am trying to remove the first side. i have already stuck a popsicle stick in between the flanges, and you can see where it has separated from the tail near the flange, but is almost all attached to the part still.


After pushing pulling and coaxing, i have gotten the whole mold separated from the part. Notice the color difference.



And.... we have the mold off. not perfect, but not bad.


and.. second part off and bolted together. the holes are drilled before anything is separated.


Here you can see i have laid bondo into the corners and begun to sand it down. I am just trying to get some radius in the corner so that it isnt so angular. The angles just dont match the curves of the tank. LOTS more work needed.



I will update soon
thanks for looking!
~Chris
 
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#5 ·
i will amend that, because that is very important. thanks

well... the tail wasnt actually originally designed as a mold, so once i am sure i have a good part.. the angle grinder will come out and i will go to town. it also make painting the frame and body-work alot easier.

thanks yall! glad you enjoy the thread.
~chris
 
#7 ·
well....
i ran into a bit of a snag...

I got the mold sanded, and bondo'ed then i sprayed a little primer in there to help me see what i was doing.


The primer goes into all the dips and mistakes...


so then i sanded it smooth (this goes for both sides)


a little bit more primer, and sanded to 1200 grit, then 4-5 coats of wax, bolted together then PVA. in other words, ready to lay up the carbon.


I had all my peices cut out and ready to go...


And then.. disaster struck. I had already practiced laying up the carbon inside the mold with the brown paper templates, but with the resin, the cloth was unmanageable.... so i ended up cutting the peices in half and laying the parts up sperately.


This will add a step, but the parts will be better.
so... they cured, and before removing them, i used a razor to mark the exact edge of the mold on the part.


then i popped them both out


I trimmed them to the line, and viola! here is the tail. (it is going to need some sanding.. dont worry, the red will come off)


so then, i will bolt the parts back together and run carbon down the seam.


The benifit with this is that i will do twill for the next tail, and it will look even better with a seam down the middle. i can get the pattern to mirror itself.

anyway.. i will post pictures as soon as the resin cures.
thanks!
~Chris
 
#10 ·
i have. there really is no way for me to vacume bag it in the current set-up. it just isnt worth it. i am hoping to get a better surface on the next one. this is my back-up tail. learn everything this time... do better next time.

so in short.. yes i have thought about it, and it just isnt worth it.

thanks for looking!
~Chris
 
#11 ·
bummer about having to do it separate. I dont know if it helps but i usually try to lay two coats of resin before i lay the cloth in. Let the first coat get tacky, brush the second coat on, let it get tacky then start with the cloth. It should help with the pocket left on the left side. If you brush on a coat and go instantly with the cloth it can wick and pull it away from your mold.

Another option for you(not nearly as nice) but you can make a tail in your mold with black FG(much easier to lay than CF). If you really wanted CF you could do an overlay like on your tank.
 
#12 ·
i am using this first part as a pilot. the final part has yet to be made, so i am going to try your method with the tacky resin if i cant find a way to vaccum bag it. That and i have found if you blow hot air over the resin it pops the bubbles.. and i didnt do that.. gonna give it a try.



well... my brother came home this weekend. He was spent 8 months training for the military, so some time WAS spent hanging out, but at the same time... i did get some work done.

I roughed up the surface where i would be laying up, re-released the molds and then bolted them together again.


then i cut the cloth mixed the resin and laid the cloth down over the seam. I used gradually wider strips of cloth starting with something only about 3/8" wide and ending up with about 3" wide. about 5 layers.


So then, the next day i took it out of the mold and cleaned up the join line. The part is extremely rigid... and light. 0.7 lbs to be exact.


and compared to some of the stuff that i cut off the tail...


so... i guess you want to see it all together. (i know i did) what do you think of the radius? i think it really makes the tail match the tank better... what do you think?


Side covers need some tweaking.


And... playing around with the headlight. the ignition mount needs to be trimmed off the triple, and the front fairing stay bracket needs to go, so that it will fit right. this is too high, but safety wire is only so good.


anyway... this tail will be a pilot then a back-up. I will fit it to the subframe, weld on the mounting tabs, and then transfer the final shape back to the mold, so i will have a clean part what is ready to bolt on. I have also learned alot of things that i can apply to the final tail. And i will still have a back-up should something happen to final part. (plus i will still have the molds)

thanks for looking!
 
#15 ·
Carbon fiber is about $30 for 36" X 50" and the resin i use is West Systems epoxy 105 resin and 206 hardener, the two shipped to your door about $55.

i order most of my stuff online, just shop around for the best price. ebay has both resin and fiber.
i hope this helps!
~Chris
 
#17 ·
i really like the lines! One thing though it looks like you used 2x2 twill on the tank and then some 3k plain weave on the side and tank. Are they different or is it just an illusion? The only thing i would say is to use the same weave for all the parts cause it will be very noticeable(i think).

I noticed on your parts you just had them primered. Do you have any issues with just primer then your pva?
 
#20 ·
I noticed on your parts you just had them primered. Do you have any issues with just primer then your pva?
We would only prime some stuff in the factory, then block it back then pva if it was a minor part or a one off. but the big bits would be primed sealed, then coated in a pigmented clear coat and then then polished to a inch of their life. then waxed 6 times. But i dont think we used PVA on those as the finish was equal to or better than a production mold.

real good job there. well done.

Did you think about making the mold in a top and bottom rather than a left and right?? that would have given you a large surface area for the carbon adn the joins will be harder to see as they will be on the outside ridge of the tail.
 
#21 ·
Great work! I am in the process of gathering materials and tools to make CF panels also. Your thread has been very helpful. Thanks for sharing!
 
#23 ·
I have a set of knives I'm making right now. I'd kinda like to do milled carbon scales. I started with g10, but I think its a bit boring. then I was lookin for the surplus carbon, but thanks to guys like snody all the f22 stuff is all bought up. would you be interested in laying up some slabs for me?
 
#24 ·
hey i didnt know you made knives. i do to.
I actually have a bunch of stuff "samples" that were thrown away. i can send you some. what thickness and size? also.. what color? i have a bunch of stuff, all pretty exotic.
what do you need?
thanks
~chris
 
#26 ·
got the tail all trimmed up and fit



i also got the tail-light hole made. it was a real pain, and now i have to re-located the mounting bracket, but we are intrepid, we carry on.


not just a little more tweaking before i transfer the lines to the mold and make the final part.
thanks for looking
~Chris
 
#31 ·
you can get carbon fiber off ebay or just search for in on the internet. it is pretty easy to find by the yard. and the resin is West Systems epoxy, 105 Resin and 206 hardener. your cheapest bet is going to be to find them online.

if you have trouble finding them i can get you some links.. but they are pretty accessible.
thanks!
~Chris
 
#33 ·
That turned out great!
 
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