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Discussion Starter #1
Hey roadster fans, my name is Kevin. I have a 1990 NA to which I am about to do incredibly stupid, but possibly very fun things. I should start by sharing a few things. I have minimal experience working on cars. I have even less experience with composites. Yet here I am, with a garage full of raw materials and the intentions of creating a raw carbon fiber body for my NA. This is an ambitious project. It's stupidly ambitious. It's one that'll likely fail, at least a few times, but nonetheless I'm geared up to give it a shot. Here's what I'm working with and what I'm working towards.

My NA has 198K miles on it. The paint is decent, but it started to bubble at the typical spots (rear quarters, working down towards the rockers.) After a little investigation with the angle grinder, the problem was much worse than I originally thought. That leaves me with a few choices, all of which share one common theme: the rusted portions have to go. I can either 1) pay a body shop to do the work. They'll cut out the rust, weld in new panels, little bit of bondo, little bit of paint, boom. We're done. 2) Cut it out myself, and go widebody! Bolt on flares! Deep dish wheels! Stance! MEATS! ...and then there's option 3. DIY. DIY Carbon Fiber parts! Hell, DIY full carbon fiber body!! Just go crazy with carbon fiber!!!

Option 1 makes so much sense. It's easy, it's fast, and it certainly won't fail. It's the logical choice. Option 2 is boring. Everyone does it. It might not handle well at the end of it. Wheels are expensive. Tires are expensive. And it's really difficult to do it well enough to not look like a low effort, slapped together drift missile, destined for the next owner to slap some douchey window sticker on it and then smash it into a lightpost in an abandoned parking lot...Option 3? Well option 3 is just stupid, really. With so much aftermarket support out there for the NA miata, why the hell would you DIY something? Let alone, why would you DIY carbon fiber? Do you know how much work it is to do carbon fiber right? I mean, people get 8 year degrees in this kind of stuff, and you think you're just gonna make it happen in your garage, with minimal materials and no experience? Gimme a break.

It's fairly obvious which option I'm going with by now. There's no need for build threads when a body shop is doing the "building." and we certainly don't need another thread on how to bolt on fender flares. So here we are, doing this introduction. My name's Kevin and I'm about to embark on a completely ridiculous, almost certainly doomed-to-fail adventure. I'm going to remake my Miata's body in carbon fiber, ridding my car of rust, and customizing it along the way.

So stick around, follow along, say "don't do that" or "you're an actual dumbass" like my brother said. Say "hey, this is pretty cool!", hell, say anything you want really. This train's rollin. Let's build some ****.
 

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Train wreck waiting to happen for sure.

Aside from that, as a fellow fabricator, a few words of advice:
1. Prep is the most important step
2. Try to think of how you want it to be in the end
3. Take your time. If you start to feel impatient and want to rush a step, sometimes is best to just walk away and come back to it later.
4. Do it right the first time.
5. Don't cut corners.
6. Be realistic.

If you are planning to do something this extensive, there might be a market for it, so it may be worth making molds to reproduce your work down the line.
 

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Discussion Starter #4 (Edited)
Today was my first day of christmas vacation. Lady still had to work today, so I had a good solid day to get going with this and try to make some progress. Spoiler alert: I didn't make much progress.

To get this out of the way first and foremost, I'm mainly doing this as a fun experiment and a way to maybe learn a thing or two about autobody work and composites. Do I expect this project to work perfectly, or even well? No, I don't. So when you're reading along and commenting, try to keep that in mind. I'm experimenting, I'm having fun, I'm realizing my little kid dream of "building" a car in the best way I can with what I've got going for me. You're going to see some unconventional tactics. You're probably going to see some stuff that makes you scratch your head and wonder how I'm able to form complete sentences. But I'm gonna have some fun along the way, and that's all I'm going for.

So with the disclaimer out of the way I should start, I guess, by laying out my end goal for you. First: I want to rebuild my OEM rear fenders with a carbon fiber skin. I want these skins to be attached to the body with no visible rivets, screws, or other fasteners. I'm actually going to force the carbon skin into a mold-lock scenario in order to hold it in place. Think about it like this if you're not familiar with what I'm saying. If you were to lay up carbon fiber on a basketball, you could do 1/4 of it and pop it off no problem. You could do all the way up to 1/2 of it, and still pop it off no problem. (ignore the ridges in the ball for the sake of this demonstration) But once you get over 1/2 way, say to 2/3 coverage, that ball is locked in there forever. Most of the time when working with composites that's a bad thing. But I'm going to try to play that to my advantage and use it as a mechanism to secure the carbon skins to the car. The second part of this project will be to eliminate the pop-up headlights, add carbon fiber skins to the front fenders, and add a carbon fiber hood with a ram air intake in the process. This is stupid. This is not going to work. I can't wait to try it.

Now, this is where I might lose favor with you folks. I love the Porsche 911. I love the Datsun 240z. I love the Miata. When I'm designing my new front end, I'm going to pull inspiration from all of those. Will it look a little bit like a knock-off Porsche front end when I'm done? Yeah, maybe it will. But hey, it's my weird project car and I'm gonna build it exactly how I like it (or at least try to).

So the first of the two parts. CF skins for the rear quarters to cover up some of that nasty rust. And I mean NASTY rust.
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My plan here defies everything that's known to work when it comes to composites. I'm going to patch up the rust holes with a whole lot of bondo. Get everything looking smooth enough to pass as a decent fender. Keep in mind, I've never done anything with bondo before today. I'm as much a rookie as I could be. But nonetheless, patch it up with bondo, smooth it into a wheel arch, and then I'm just going to lay the CF on top of that, essentially using the car as a mold. I know that I'll need to paint the bondo first, and I know I'll need to add release wax and follow proper protocol as far as making it able to release from the car. Here's my mediocre bondo jobs below.

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The only goal here is to make a good base for the carbon skin to come out smooth, and I think I'm making progress there. I have a couple more rounds of adding and subtracting to do to get it to where I'm happy with it. But hey, first day, not bad. I also understand that the rust has to get cut out or I'm just dooming myself further. I have a plan there. It's probably not going to work, but I'm gonna give it a go. I'll explain that when the time comes. That's about all the progress I made on the rear today. Moving on to part two and the front of the car.

Here's where I'm really flying by the seat of my pants. I mean, bondo is bondo. Slap it on, sand it off, rinse repeat. But this is new territory. I mentioned before the 911 inspirations. Well, I want to ditch the pop-ups in favor of stationary round headlights, the back of which swoop back to the windshield base. My plan here is to use foam to get the shape about where I want it, add a layer of bondo, paint it, and then lay the carbon over the top of that. After that, I'll have to figure out how to parlay that into a hood to match.

Deleting the headlight motors and moving the bulbs forward gains me some valuable space on the cold side of the engine. I'm planning to move the air intake to the cold side and whip up some sort of ram air intake setup. The customized look will be nice too.

So here's where I'm at with the front headlight setup progress. I used styrofoam layers and spray foam to hold them together. It takes 8 hours for the spray foam to cure, but at about an hour in it felt pretty solid. There's some hot melt glue in there too for good measure, but that was proving difficult to get down in time before it hardened up.

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The next day I get to work, I'll do some more due diligence in the bondo department and begin shaping the foam headlight housing/fender combo.

If you're still reading, thanks for following along! Hopefully we get to see some good results at the end of this experiment. If not, then hopefully we get some good laughs out of it!

Cheers folks

Kevin
 

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Discussion Starter #6
Train wreck waiting to happen for sure.

Aside from that, as a fellow fabricator, a few words of advice:
1. Prep is the most important step
2. Try to think of how you want it to be in the end
3. Take your time. If you start to feel impatient and want to rush a step, sometimes is best to just walk away and come back to it later.
4. Do it right the first time.
5. Don't cut corners.
6. Be realistic.

If you are planning to do something this extensive, there might be a market for it, so it may be worth making molds to reproduce your work down the line.
Thanks for the advice! I'm planning to put a ton of time into prep. That's going to be 99% of the project. I have a pretty clear vision of what I want the car to look like when I'm done. So that part's taken care of. I did find myself shutting down about an hour earlier than I planned. I started to get a little careless and sloppy, so I switched over to cleaning instead. I feel I left off at a good spot. I'm not sure I'll be doing it "right"? Because I'm experimenting here. The goal is to kind of try new techniques and maybe come up with something that works for me. Same sentiment for the cutting corners part. There's no guideline here that I'm following, I'm winging this whole thing. I understand the sentiment though and I appreciate it.

As for being realistic? I'm making a carbon fiber body for a 30 year old mazda with 0 autobody experience and 0 composites experience. This project is about as unrealistic as it can get, so I'm gonna turn it up to 11. Chances of it being a trainwreck are quite high, but hey. Let's have some fun while we fail.
 

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Discussion Starter #7
I snuck out to the garage this morning while the lady and the pup caught up on some rest. Or so I thought. Apparently shaving styrofoam isn't as quiet as I thought. I made some decent progress on the front passenger headlight/fender assembly. I have a good bit of work to do still. Shaping this and getting it right is going to be pretty difficult. For front to back shape, I'm trying to replicate the slight curve from the rear tail light up to the middle of the door and keep my headlight/fender curve close to that, if that makes sense? For top to bottom, I want the fender/headlight assembly to be one smooth curve instead of how it looks now where the two are distinct pieces.

I have a whole lot of material to take away here still. I'm trying to be conservative so I don't have to do a full re-do. Here's my progress so far. Long way to go before I'm ready to put a coat of bondo on it and make it a "real" mold, but hey, it's coming along somewhat.
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For replicating it on the other side, I'm going to use some heavy gauge wire and bend a skeleton of sorts. One spine running down the top center, then ribs every few inches. This will allow me to simply take the ribs, and flip them around over the center spine, and set them down over the foam to check how close I am to achieving some sort of symmetry. I'll also be relying heavily on feeling and eyeballing it. Once I have them symmetrical I'll start making the mold for the ram air intake on the cold side of the motor. Still unsure what that's going to look like and whether it'll be part of the hood or the fender/light. I definitely want to put some sort of scoop/functional intake there. I think it'll look cool, it'll add some function (maybe, idk, I'm definitely no performance engineer) and being purposely asymmetrical may help with the fact that it's probably going to be asymmetrical.

I'm also unsure where I should make the fenders stop and the hood begin. Down the spine would be best for engine bay access, but would look the worst. Down the seam (blue tape line in the photo above, hard to see but it's there to the right of the headlight) would be best for looks, but might limit engine bay access.

So small bit of progress this morning, but I wasn't expecting to find time to work on this until after christmas, so I'm definitely happy with it. The little cheesegrater looking Stanley tool I got is pretty awesome. If you use a lot of pressure you can hog off material quickly, but if you go for light quick strokes you can actually get a somewhat smooth surface.

Link to the tool here: https://www.homedepot.com/p/Stanley-15-3-4-in-x-1-5-8-in-Surform-Flat-Mill-File-21-295/100155566

Also, my carbon arrived! Think about how ridiculous of a world we live in. I clicked a few buttons on Thursday morning. 48 hours later, I have a 4 ft x 30 ft roll of carbon fiber in my garage. Amazing stuff really.

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I have about a gallon of resin leftover from some woodworking projects. I'm going to make a few test pieces of carbon with that resin to see if I'll be able to reuse it or if I need to get some more expensive epoxy like west system or the like.

I should mention that for the end goal, I don't necessarily want the panels to be glass smooth. In fact, I kind want there to be some texture to it. Like if I run my hand over it, I want there to be some tactile feedback. I'll get the texture right with small test pieces before moving on to the big panels. Maybe I'll make a phone stand for my desk or some BS like that.

This'll probably be my last update until after the holidays. Hope you all get to spend some time with family over the next couple weeks and take some time to enjoy some of the simpler things in life. Cheers folks.

Kevin
 

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Discussion Starter #8
Well I couldn't wait. The carbon got here today, the metallic pigment got here today, I had to test it out. I laid down some tyvek tape on my decklid (Old woodworking trick coming in clutch there, epoxy won't stick to tyvek tape) and cut out a small 6"x6" section of cloth. I mixed up some of the old ArtResin epoxy I had laying around with wayyy too much pigment (a little goes a long way here, for future notice) and these are the results. I was using a stick at first so I tore some of the fibers, but after I started using an old gift card I got pretty close the results I want. Textured metallic green carbon fiber. For a quick test, I'm happy. The third picture is best.

This was cool, can't wait to see how it cures up and pops off. Rigidity tests coming soon!

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Discussion Starter #9
So the first carbon test yielded unsuccessful results. I won't call the test unsuccessful though, because I learned that a single layer using the old epoxy I had laying around won't cut it. It cured and is no longer tacky, but is still very much flexible. I'm able to fold it, roll it, just about everything. It's about as rigid as two sheets of construction paper, but much more flexible. I'm sure this could be useful in some applications but it's not gonna cut it for body panels.

The texture is bang on for what I'm looking to produce. It's smooth but textured, and most importantly it is uniform in the places where I used a gift card instead of a piece of wood. I will likely skip the pigment in the epoxy. It's splotchy and it just doesn't look great in general. Though perhaps I used too much, and less pigment will look better.

I ordered new resin - West Systems epoxy 105 and 207 hardener. This system has an intermediate pot time (24 mins) working time (110 mins) and cure time (15 hours). I'm not sure this was the right choice though. The pot time seems awfully low. I think I'll need an assistant when I begin to lay up some of the larger panels, working with only very small cups of resin and stirring up new ones often. I'm sure my wife will be thrilled to volunteer, though maybe I can entice my brother who is also a Miata nut. Epoxy is arriving today and the holiday rush is all but over. I've got all of next week off which I'm sure will be a nice mixture of relaxation and carbon experiments. If I can get one rear quarter panel finished next week, I'll deem that an enormous success.
 

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You need more layers for stiffness. Try also to experiment with core materials and ribs to add stiffness.
 

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Discussion Starter #11
You need more layers for stiffness. Try also to experiment with core materials and ribs to add stiffness.
Yup, I just found that out for myself. Thank you for the tip! Definitely going to need layers. I think that a 45* offset will also likely add the most stiffness, but I'm unsure if the width of my material allows for that. Unless I can do a patchwork underlayment with multiple sheets of material laid up side by side. I'd imagine there'd be weak spot there along the seam. If you know anything about underlayment and offsets, please chime in.
 

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Discussion Starter #12
The West System epoxy I picked up is a success so far. It's a much needed upgrade from the old, yellowed art resin epoxy I used the first time. I got the 105 resin / 207 hardener. I may also pick up some of the extra slow hardener for larger layups like the hood and the front quarters/headlights where I'll need more time.

I laid up another single layer piece and it seems to be just as wiggly as the first test piece; however, it set up in ~12 hours which is a huge improvement. I just went and laid a second layer over the top of that, we'll see how much stiffness that'll gain me. As HarryB suggested I'll be looking into core material. I wonder if there's some core materials out there that can net me stiffness without thickness. Anyway, we'll see how the two layer experiment comes out and go from there. I'll update tonight or tomorrow morning with my findings.
 

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Composite materials do not work like that; you need thickness for stiffness. Carbon/glass fiber and the like are excellent in in-plane tensile loading (everything that pulls in parallel to the skin) and suck at pretty much anything else. The more core thickness you add the more stiffness you get (actually stiffness is squared with thickness). This is not due to the core stiffness itself, it is from separating the two skins. Take a quick look/reading of how I-section beams work in bending; it is pretty much the same here.
 

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Discussion Starter #14
A quick update on the second test piece. With two layers it is plenty stiff enough to hold it's shape. I think I'll give one quarter panel a shot this week with a two layer structure. If it turns out wiggly I will try to add another backing layer. I'll need to do another test piece with seams in the bottom layer + a single smooth top sheet to see if there are any problems with that construction method (seeing seams in final product, weak points, weird grain patterns, etc.).

I'm starting to feel like this might just work out the way I want it to, knock wood.
 

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This is one of those threads people will look back at in 10 years' time. CR.net history in the making.
 

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Discussion Starter #16
To everyone who is following along to say "I told you so!" when this failed spectacularly...it's your time to shine haha

It's only a half-fail I think. I laid up one layer on the passenger rear quarter and I got a few spots that look really ugly, a few places where I have an almost wrinkly texture (picture when you stretch plastic wrap over a bowl and it doesn't get perfectly flat, but not a deep enough wrinkle to make me want to throw it away) I'm hoping with a second layer things will smooth out and look okay.

Some things I learned. I don't know that these will be useful to anyone making carbon fiber in any sort of legitimate way, but we're doin' the blog thing so here we go.
  • Don't ever use tape to hold up your fabric while you lay it up. You'll be able to see those strands that are pulled up very apparently in the final product. Luckily this is just the bottom layer, so I'll never see it. But yeah, don't use tape.
  • I thought it'd be okay to cut the piece larger than needed and just cut off the excess as I was wetting it up. That wasn't a great plan. Things get messy, fast. The closer you can get to the exact size needed the better.
  • Since I was using the car as a mold, I needed to put something down to make it release. I used a combination of plastic wrap and tyvek tape. The parts where I used tyvek tape look great. The plastic wrap stuck to the car at first, but seems like it came loose and gave me that plastic-wrap-over-a-bowl look. In the future I'm going to use all tape or look into mold release waxes which will likely give even better results.
  • Do you think that's enough epoxy? Well it's not. Mix up literally double that. And then you'll still need to make more. You do not want to have to stop squeegeing/credit carding/spreading epoxy around to mix up more epoxy. A minute of mixing feels like an hour when you're staring at that piece that's laying wrong.
  • This is the controversial one (well most controversial one I guess) When things get really messy just use your hands. Especially if you're tucking the carbon up into what will be unseen places, just mush that stuff up there with your hands. This is easier when it's a little tacky honestly, so like an hour after you first wet it up. Looks like **** with the finger prints and all, but for a base layer in an unseen spot, it works.
I'm writing this in bed with my pup sleeping on me, so no way I can sneak out to grab photos now. And NYE is always busy, so photos next year likely. Not sure when I'll be able to find time for layer #2. It's a pretty long process and I've got a busy January coming up.

Cheers, happy New year!
 

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Discussion Starter #18
invest in nitrile gloves and partal paste.
Partall #2 now on order. I had heard about meguiars gold but was having some trouble finding it. The plastic wrap method is out for future parts, and though the tyvek tape works it leaves a residue and you can kind of see the seams in the tape. Thanks for the tip, hopefully that helps the other parts go a bit smoother.
 

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Discussion Starter #19
Hey everyone, closing the loop on this project here, for the sake of completeness. Long story short: it "worked" but it looks terrible. There's a reason carbon is expensive and that's because it's very difficult to make it properly. Homebrewing carbon would work if this was a racecar application, where looks are less important than function. But since this is a street car that I want to look nice as well as drive nice, these parts are just not good enough.

To those who were following just to say "I told you so!" it's round 2 for you.

This was largely a waste of $300, but I had some fun doing the project. Funny story though; I actually ended up going to an urgent care as I was breaking out in crazy hives all over my body and face. My eyes were really swollen so I started to worry there. Turns out I am extremely sensitive to epoxy resin, and wiping the excess from my gloves onto my pants and sweatshirt was a majorly dumb move. A week of steroids later and I was fine. I'd be lying if I said this isn't contributing to my decision to abandon this project. I think next I'll try my hand at DIYing some stuff with metal. Maybe fabrication will go better for me than composites did. Here's some photos of the parts after "completion." Enjoy!

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They don’t look bad at all! You did really well, especially for a first attempt in full DIY fashion! Sad to see you won’t take this forward, that would be a very good starting point! Can’t say I understand though. Hope this thread will become a more successful metal adventure!
 
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