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Thread: DIY Carbon Fiber Parts Thread

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    Senior Member Mnemuth's Avatar
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    DIY Carbon Fiber Parts Thread

    Okay, I was in the basement making a dry sump oil pump belt shroud today and thought it might be interesting (for 3 or 4 folks out there in the virtual world) if I documented how to do it. I taught myself this stuff last year and with a significant amount of frustration. I still generally suck at it and make no claims otherwise.

    So, read this at YOUR OWN RISK.

    Now, on to what sort of stuff you need to buy in order for all this to work.

    A vacuum pump. And don't get a crappy one or make one from an AC compressor. Here is the one I use.

    20161112_173236.jpg

    If you are infusing (drawing a vacuum on the layup and letting the vacuum pump pull in the resin), then a catch pot is a good idea. I guess making one yourself is okay here, but I got one that makes it easy.

    20161112_173310.jpg

    A cup fits right in there. The idea is that some of the resin flows out of the infusion and it would not be good to have it enter the vacuum pump.

    20161112_173327.jpg

    You will need a scale in most cases to measure out the correct amount of epoxy hardener. I got this dude from Harbor Freight for a song. It has been used.

    20161112_174302.jpg
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    Senior Member chetrickerman's Avatar
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    FUCK YES

    I can finally start making my own carbon parts

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    Senior Member Mnemuth's Avatar
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    In terms of consumables, there are several.

    20161112_173915.jpg

    The roll of black stuff with a white backer is what you need to stick the vacuum bag to the mould. I'd hate to think what @CrazyIvan would do with sticky tape like that...

    The t-connector is important for when you set up the infusion using the spiral white plastic stuff winding around the outside of the photograph. The white thing on the right is to pinch a hose when you need to stop resin flow. The propeller thing is actually super important when making a large part. You really cannot spend too much time mixing the resin and doing so without making bubbles. This guy makes sure the epoxy actually cures...

    The green stuff allows the resin to flow throughout the part and the white fabric is peel ply, which lets resin flow through but you can still peel it off once it dries.
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    Senior Member Mnemuth's Avatar
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    Do NOT attempt to cut what you see below on the left without

    20161112_173424.jpg

    one of these (or something similar):

    20161112_173546.jpg

    Seriously, you cannot cut Kevlar with scissors. You might get a few inches cut with tin shears but they will dull almost immediately. Just don't bother wasting your time.

    Unless you are working with prepreg and have an autoclave and/or an oven, you will likely find some trouble laying down the carbon fiber. This stuff helps, but it is difficult to use it in moderation.

    20161112_173511.jpg

    Airtac is a favorite.
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    Senior Member Mnemuth's Avatar
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    There is a lot of stuff on the internet about how to prepare a mould and what you need to do to get it to actually release a part. I've tried a number of things and many of them failed miserably.

    I would let a new mould dry for a good long time (few weeks) and wax the hell out of it as a cheap way to go. Or use this stuff:

    20161112_173355.jpg

    The one on the right prepares a new mould that might have some micro porosity. The one on the left is a mould release.

    You might have another way but Frekote seems to work well for me.

    By the way, a large carbon fiber part layup is not exactly cheap. It sucks to have a failure when there is $$$ in carbon wasted not to mention the time.

    More to come tomorrow when I lay up a carbon fiber (and Kevlar) infusion.
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    Senior Member Mnemuth's Avatar
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    One more thing to ponder. Reinforcement is important and you can get carbon or Kevlar 'tape' to selectively apply to areas where more strength is required.

    20161112_174116.jpg

    It is also sold in socks, or woven such that it fits over a cylinder. So, you can get a nice weave pattern on your intercooler piping if you can figure out how to make a mandrel that can be removed from the internal kinks.
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    how much much is your material cost for something like your dry sump cover?

    Sent from my SAMSUNG-SM-G891A using Tapatalk
    Last edited by JeremyR; 11-13-2016 at 02:25 PM.

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    Senior Member Mnemuth's Avatar
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    Quote Originally Posted by JeremyR View Post
    how much much is your material cost for something like your dry sump cover?

    Sent from my SAMSUNG-SM-G891A using Tapatalk
    Really not that much. It wouldn't take more than $50 I'm sure. Unless you consider the machining for the parts to hold it together...that would be much more.
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    Senior Member Mnemuth's Avatar
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    The best way to start is to lay the tape around the outer edge of the flange. Then run the spiral tube around the rim--this allows the air and epoxy a sway out.

    Layup1.jpg

    Then cut out all the various layers and reinforcements and lay it up. Be careful to cut enough bagging material. It is easy to forget that it must conform to all the inner shapes.

    BagSize.jpg

    The peel ply goes on first. This creates a barrier between the breather and the bag. It leaves a nice dry look.

    PeelPly.jpg

    And the breather laid on top. I have begun sticking the bag to the flange.

    Breather.jpg
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    Senior Member Mnemuth's Avatar
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    The bag must be pleated on the side for it to work (the outside perimeter length of the bag is greater than the mould). Here is the infusion set up.

    SetUp.jpg

    The infusion process begins by opening the feed line to the part while it is all under vacuum.

    Infuse1.jpg

    The resin flows through the composite toward the outer edge spiral stuff.

    Infuse2.jpg

    Until it reaches the edge.

    Infuse4.jpg

    I leave the vacuum on once the entire part is wetted out. This pulls as much resin out as possible and removes air bubbles as well.

    We'll see what I have tomorrow when I pull the part. Looks easy, right?
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    You make this look so simple I'm tempted to try it..

    For the initial layers of carbon you put in the mold, are you wetting them with epoxy to get it to form to the curves before vacuuming? Or do you just lay it up as best as you can and rely on the vac process to squeeze it into the proper shape?

    Do you bake the parts at all? Or just wait for the epoxy to dry naturally?

    Thanks for the info so far!

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    Senior Member Mnemuth's Avatar
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    Quote Originally Posted by saytheb View Post
    You make this look so simple I'm tempted to try it..

    For the initial layers of carbon you put in the mold, are you wetting them with epoxy to get it to form to the curves before vacuuming? Or do you just lay it up as best as you can and rely on the vac process to squeeze it into the proper shape?

    Do you bake the parts at all? Or just wait for the epoxy to dry naturally?

    Thanks for the info so far!
    I do not lay down a gel coat on the mould prior to putting down the carbon. It makes sense to do so since it promotes a clean surface without weave pushing through. There are a couple reasons why I don't. First, the Frekote works so well that the epoxy will not stay flat on the mould--it draws together leaving bare spots all over. Second, I usually finish the surface with a chemical coating (paint or clearcoat). Carbon looks cool, but epoxy is not very resilient to uv light.

    I do not bake the part because I do not have an oven. I have been looking for a heat blanket for just that reason. If I had an oven I would just switch to prepreg and be done with it. Prepreg just makes everything more expensive, especially for larger parts.
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    Senior Member chetrickerman's Avatar
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    how did you make the mold?

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    Senior Member Mnemuth's Avatar
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    Quote Originally Posted by chetrickerman View Post
    how did you make the mold?
    I put a good coat of paint on the aluminum part and made sure it was nice and smooth and cured. Then I brushed on polyester gel coat (made for moulds) as the black interior mould surface. Then I took ordinary fiberglass resin and cloth and built up the mould on top of the gel coat once it cured to the point of being tacky.

    I made the flange part by sticking the shroud to a piece of glass that had been waxed. I just painted the gel coat onto the glass about two inches around the perimeter and did the same with the fiberglass.
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    Any tips for ensuring the correct part thickness? I'm curious if measuring the part thickness with a micrometer, then measuring the carbon fiber dry thickness will get you close enough to a perfect fit.. I'm considering try to mock up one of the small interior trim pieces so fits going to be a concern obviously.

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    Senior Member Mnemuth's Avatar
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    Quote Originally Posted by saytheb View Post
    Any tips for ensuring the correct part thickness? I'm curious if measuring the part thickness with a micrometer, then measuring the carbon fiber dry thickness will get you close enough to a perfect fit.. I'm considering try to mock up one of the small interior trim pieces so fits going to be a concern obviously.
    Trial end error. Most aesthetic parts only need be 2-3 layers thick.

    The trouble with this stuff is the work you end up spending on moulds. Get good at mould making and you will figure out the rest.
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    Senior Member Mnemuth's Avatar
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    The part is a keeper. The interior looks great, but it is interesting to note the two domes where the spindles go. Each are nicely radiused where the mould is actually chamfered.

    20161114_194716.jpg

    I'm not at the shop so cannot trim the edge of the part.

    The carbon was not loose enough to follow the shape of the turned aluminum cap. I chamfered it because it is easy to do but there is no reason a radius won't work just as well. I can sand down the extra epoxy to the radius on the part.

    20161114_194726.jpg

    The sides look great.

    20161114_194745.jpg

    I'll take some time to sand this one and maybe clearcoat it using some automotive clear that I have left over from the hood project.

    Until you have held this stuff in your hand, it is difficult to describe how something that weighs like paper can be as hard to bend as mild steel. And this is two carbon layers, a carbon/Kevlar layer, and an inside carbon layer.

    I should have built the entire thing from carbon/Kevlar weave for maximum impact resistance but everybody likes the carbon look. Too bad Chet has a 240 belt or I could send him one. Of course he would bitch about a 4 layer part weighing too much and want one made with 3 and no clear coat because it adds weight.
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    Senior Member Mnemuth's Avatar
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    Keep in mind that I could make a few tweaks yet and have a near perfect looking part. The trouble is that I only need one (well, until the car is in a wall when I need another). I'd have spent more time on the mould if I were making more than a few of these (and used epoxy gel coat).

    What is cool about this type of thing is that it does not require a shop full of equipment. You can do it in your apartment and make really cool stuff. There is an abundance of good information online about it and a range of stuff you can make (outside of car parts).

    A few points to consider.

    • do not buy regular plastic thinking it will do for vacuum bagging material, it will disappoint
    • don't waste time on all the release agents everyone else uses to get wonderful results on moulds (use Frekote)
    • do not think you failed until you are 5 parts that suck
    • start small and work your way up (i.e., DO NOT start with an Evo hood)
    • more than you might initially think can be worked back to near perfect, some adjustment required
    • stir the epoxy, more than you think you need to
    • first class moulds cost tens to hundreds of thousands of dollars, not bad will often do just fine with some work
    • second grade carbon is nearly perfect, cut out the defects or put them in a middle ply
    • I have had good luck with http://compositeenvisions.com/ (I like the fact that mods do not hound me for such things here)

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  19. #19
    Senior Member chetrickerman's Avatar
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    Quote Originally Posted by Mnemuth View Post
    The part is a keeper. The interior looks great, but it is interesting to note the two domes where the spindles go. Each are nicely radiused where the mould is actually chamfered.

    20161114_194716.jpg

    I'm not at the shop so cannot trim the edge of the part.

    The carbon was not loose enough to follow the shape of the turned aluminum cap. I chamfered it because it is easy to do but there is no reason a radius won't work just as well. I can sand down the extra epoxy to the radius on the part.

    20161114_194726.jpg

    The sides look great.

    20161114_194745.jpg

    I'll take some time to sand this one and maybe clearcoat it using some automotive clear that I have left over from the hood project.

    Until you have held this stuff in your hand, it is difficult to describe how something that weighs like paper can be as hard to bend as mild steel. And this is two carbon layers, a carbon/Kevlar layer, and an inside carbon layer.

    I should have built the entire thing from carbon/Kevlar weave for maximum impact resistance but everybody likes the carbon look. Too bad Chet has a 240 belt or I could send him one. Of course he would bitch about a 4 layer part weighing too much and want one made with 3 and no clear coat because it adds weight.
    HAHAAHAHAHAHAHAHAAHAHHAHAHAHAHA

    Looks beautiful though!

    I legit might start doing this stuff this winter

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