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Thread: How To: Make a carbon fiber exhaust bracket (or any small CF part)

  1. #1
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    Default How To: Make a carbon fiber exhaust bracket (or any small CF part)

    You will need:
    Carbon Fiber cloth (Amount depends on what you are making)
    Epoxy (^^)
    Paper salad bowl
    Mixing stick
    2" paint brush (cheap)
    Roller (optional)
    relese fabric (enough to go around the part once)
    breather fabric (enough to go around the part once)
    Scissors/roller cutter
    Cutting mat
    Ruler
    release/carnuaba wax
    PVA/Mold release
    Reynolds handi-vac and 1 gallon handyvac bag
    Nitrile Gloves
    Dremel w/cutting disks or diamond cutting wheel

    Before you begin: clear your work area and put on your gloves. Wear clothes that you wont cry over if they get some epoxy or wax on them.

    1) Get whatever part you want and clean the crap out of it. Even the slightest imperfection will show up in the CF part so spend the time to do this right. It must be COMPLETELY clean and free of wax, dirt, etc. If it is a hard part, consider using something to fill in the imperfections (bondo, etc).
    Here is my exhaust bracket from the SV. It is important to note that all the cleaning, etc I am doing to the BACK SIDE of the part. I will explain more on that later.


    2) Once the part is fully cleaned, wax the entire piece with mold release wax. I use Partall Paste Wax #2 however any pure carnuaba wax should do (Mothers, etc). Let the piece haze over and then buff the wax, just as you would if you were waxing your car or bike. Once the wax is done, coat the piece with PVA (PolyVinyl Alcohol) mold release agent. Essentially this creates a very thin film between the part and the epoxy making later stages easy. Simply put some PVA on a shop towel and go over the part. It dries quickly so do not go back over an area you covered, just hit it once and then let the piece dry 30-60 minutes. **NOTE** some people have had good results skipping the PVA step. I prefer to be thorough.


    3) Once the wax is done and the PVA is set up we are ready to mix epoxy. Most brands are a 2:1 mix ratio. Pay attention to this as it is unforgiving. I typically use West epoxy however this time I am trying something new and using AeroMarine products. Dispense the Resin and the hardener (in the correct proportions) into a mixing bowl. I just use cheap paper bowls as shown here. Mix thoroughly with your mixing stick. Take the extra time here to ensure it is properly mixxed.




    4) Get a clear workspace and put the part in a spot where it is ok if you get a little epoxy on it. I just put it up on a box. Using the 2" paint brush, put a layer of epoxy on the BACK of your part. Be thorough and make sure that you completely cover the part. Remember that the FRONT of the CF part is going to be up against the BACK of your original part. Trust me on this. Set this aside and let the epoxy set up a little bit.




    5) using your rolling cutter, scissors, ruler, and cutting mat: cut out the CF pieces you will need. Cosmetic pieces you can get away with 3-4 layers, structural pieces (like this exhaust bracket) you want 6-10. Cut the pieces such that they completely cover the part with an extra 1" all the way around the outside. I am not showing you pictures, I assume you know how to use scissors at this stage :-p

    6) Once your pieces are cut, put the first layer of CF on top of the epoxy you just put down. Use your fingers to push the fabric into the epoxy. You will see the CF cloth "wet out" as the epoxy seeps through, this is good. Pay special attention to corners, angles, anyplace where the cloth may normally try to pull away from. Smooth the entire thing down well with your fingers and then apply the next layer of CF cloth. Once it stops "wetting out", use your paintbrush and apply another layer of epoxy to the top of the CF. Rinse and repeat until all layers are applied and thoroughly wet.
    This is my first piece of CF fabric, you can clearly see the outline of the bracket underneath.


    A few more layers applied.


    7) The less epoxy in your part, the stronger it is. With this in mind you use something (in this case a roller) to squeeze the epoxy out of the part. Be careful not to shift the CF fabric while doing this. Go over it a few times and it forces the epoxy out. Blot up the excess with a shop towel.


    8) cut out the release fabric and breather fabric. Enough to go around the part once. The release fabric is a specific technical fabric with a very tight weave. It doesnt bond to epoxy much so it serves as a good barrier.


    9) wrap the release fabric around your part. be careful not to shift the CF at all. Once the part is completely wrapped with release fabric, then wrap the breather around the part. The release fabric serves two purposes; it prevents the breather (and anything else) from bonding to the piece and it also serves to wick away any excess epoxy. The breather fabric also serves two purposes; it absorbs the excess epoxy that is wicked away by the release fabric and it also provices a way for air to reach the part once it has been vacuum bagged. Once the part has been completely wrapped, put it into the gallon vacuum bag.


    10) Use the reynolds handi-vac to vacuum bag the part. This is a great little tool that you can pick up at your local grocery store, it is used for food preservation and will cost you about $20. You can see here how the vacuum pulls the fabric on top of the part very tightly and easily see the outline of the bracket, this will serve to further pull the excess epoxy away as well as making sure that the CF fabric conforms tightly to the part for an exact duplicate.


    Set the part aside to cure, usually 24hrs at 70 degrees. More to come as I unbag the part on Sunday!

  2. #2
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    Default Part 2: the unbagging

    11) After you are sure that the part has had sufficient time to cure, remove it from the vacuum bag and pull off the release fabric. It should look something like this:





    Another perk of the release fabric is that it gives the back of your piece a very nice and finished looking texture as seen in the above pic.

    12) Put on your respirator/breather mask. A particle mask IS NOT sufficient for this. Dont be cheap, CF and Fiberglass dust can permanently harm your lungs. Buy a quality respirator with charcoal filters; use it when sanding, painting, you name it.


    13) I use a scratch awl to mark around the outside of the piece. You can use a pencil but I prefer the mark as it is easier to see once dust starts kicking up plus it provides just that tiniest little depth to help guide your cutting blade.


    14) Gently pry the original bracket off of the CF. A plastic wedge or popsicle stick, etc will work great for this. If you waxed properly and used PVA, it should just pop right off without any trouble.


    and once the bracket is removed it should look something like this:


    Hey! This doesnt look all snazzy like the CF stuff I have seen??!? Thats ok, it will be dull looking for now. Trust me =)

    15) Bust out your trusty dremel with a diamond cutting blade and cut the piece out along the scratch lines you made with the awl in step 13. Avoid curvey areas and just "rough out" the piece so that it is free of the surrounding CF.


    16) Use a drill to gently go through the CF where the bolt holes will be. Use a bit big enough to get your smallest dremel grinder through. Sorry, no pics =) If you cant see where you need to drill at this point, put down the CF and take up knitting.

    17) Change bits in your dremel to the aforementioned grinder/sander (I have a diamond grinding bit as shown here) and go around the outside of the part, this is where you go right up to the scratch line and round out any areas that need it. Also you round out the bolt holes as needed. This had 1 round hole and 2 slots. Dampen a shop towel and wipe away the dust. The water in the towel will also clear off the PVA that was left on the surface and your part should look a little bit closer to what you would expect at this point.


    17a) if you are anal like me, you can use a sanding block on the straight edges of the part to make sure that everything, well, is straight =) the dremel can leave a little bit of a wavy line if you arent careful, the straight edge corrects this and gives it a very nice finished appearance.

    18) Clean the part well, first with water, then with acetone, then go over it with a tack cloth to remove any lint/dust/whatever that might be remaining. It should be dry and clear of any contaminants at this point. Set it up somewhere and shoot it with a high quality polyeurethane clear top coat. A light coat at first, followed by a few more heavier coats to suit your tastes.

    Carbon Fiber is very prone to UV discolorization (ie: the sun) so you need a good top coat with UV protection.

    Once done, if you are anal (like me!) you can wet sand with 1500 grit then 2000 grit paper and buff using a rubbing compound. After a few days you can wax the part and make it ooh-ahh shiney enough that even Bruce would approve.

    here it is drying =)





    Voila! A CF exhaust bracket that saves weight, is highly durable, and looks badass..all for less than 2hrs of work.

    Oh, and since I know someone is going to ask. The original bracket weighed 5oz.


    The CF bracket...

    Yeah...you are reading that right. It is 1/2 ounce =)
    Last edited by DucatiMichael; 11-14-2010 at 10:23 AM.

  3. #3
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    Default

    Nice job Mike!!

    Something I learned from the woodshop and sanding stuff.. use a box fan with a furnace filter and have it blow away from your work area, it'll help pull the CF dust particles away from you and trap em in the filter.

    If you or anyone does a lot of this, make your own downdraft sanding table using peg board from home center. Build a box to support the fan, place the filter on top, then the peg board and you have a downdraft sanding table.
    Last edited by Pestilence; 11-14-2010 at 10:25 AM.
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  4. #4
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    Quote Originally Posted by Pestilence View Post
    Nice job Mike!!

    Something I learned from the woodshop and sanding stuff.. use a box fan with a furnace filter and have it blow away from your work area, it'll help pull the CF dust particles away from you and trap em in the filter.

    If you or anyone does a lot of this, make your own downdraft sanding table using peg board from home center. Build a box to support the fan, place the filter on top, then the peg board and you have a downdraft sanding table.
    You sir, are a genius. That is my next project =)

  5. #5
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    Sweet. That seems like it could be addicting. 4.5 oz here, 4.5 oz there...
    Retired! LRRS/CCS EX #212 | Woodcraft| Armour Bodies | Dainese USA |


  6. #6
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    that is awesome mike.
    2nd owner of theHawhandcordone

    WHOA


    #dirtyprince

  7. #7
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    Wow nice job!
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  8. #8
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    Cool project man!!

    Are you sure it is strong/flexible enough? Usually high quality cf brackets have some aluminum inserts to prevent tearing and such.
    "If we all worked on the assumption that what is accepted as true were really true, there would be little hope of advance" - Orville Wright

    "Freedom is not defined by safety. Freedom is defined by the ability of citizens to live without government interference. Government cannot create a world without risks, nor would we really wish to live in such a fictional place. Only a totalitarian society would even claim absolute safety as a worthy ideal, because it would requre total state control over its citizens' lives. Liberty has meaning only if we still believe in it when terrible things happen and a false government security blanket beckons." - Ron Paul

  9. #9
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    I think it should be more than strong enough, it most definitely isnt flexible in any way but neither is the original bracket. I cant imagine I would want flex in an exhaust hanger. Time will tell for tearing I suppose althogh I really havent seen any issues with other structural items made the same way. I will definitely keep an eye on it over the next year at the track.

  10. #10
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    Very nice write up Mike! As if I don't have enough things on my list of want to do's, now I have to add this!

    If you don't mind, could provide a list of materials, prices and sources for us novices?

    My bike and car would love to have some genuine CF parts.
    R.I.P Matt V - 9/19/10

    R.I.P. Reed - 3/23/08

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