Critique My Plan

General Composites Discussions Composites Talk
#1

I’m currently deployed and won’t be home for 3 more months. I became interested in the idea of producing my own carbon fiber parts about 2 months ago, and have been researching it fairly thoroughly ever since. Since I still have a long time before I’ll actually be able to get to work, I’d like to share my plan as it currently exists in hopes that some of you more experienced folks can let me know what I’m planning right, wrong, what I should definitely change, maybe change, and if you have any tips or suggestions.

My motivation for working with carbon fiber is the same as most people’s: cars (and maybe sport bikes). I’m hoping to buy a house in 2015, so I’ve also fantasized about making household items like furniture, sinks, tubs, etc., but my main motivation is getting my car to a point where I have to anchor it down so it doesn’t float away.

I’ve read lots of threads on this site, and a few threads on others. I’ve read articles, watched videos, and just spent a lot of time sitting around thinking about every aspect I know of regarding producing carbon fiber car parts. By far, the most beneficial bit of information I’ve discovered is the three-part instructional video from Easy Composites about how to make a hood. Because of that video, I’ve been basing my whole plan around making a hood via vacuum infusion as my first project. It seems simple enough, my hood is the most simple body panel of my car, and the whole reason I got interested in making my own parts was because a guy on my car forum made his own hood successfully in one try with no prior experience.

I’d like to replace as much of my exterior with carbon fiber as possible. I kind of feel like I might be, or at least sound like, a naïve noob when I say I want to have a fully carbon fiber body, but… I want to have fully carbon fiber body.

I’m under the impression that I can produce all of these parts using vacuum infusion. Does that seem right? If not, what’s the better alternative.

By the time I get to the really complex parts, specifically the rear quarter panels which I assume are welded to the chassis, I will at least have some experience. As of now, this is the order in which I want to produce the parts:

  1. Hood
  2. Fenders
  3. Front Bumper
  4. Rear Bumper
  5. Make my own diffuser
  6. (Edit)
  7. Trunk Lid
  8. Doors
    – Point of no return –
  9. Roof
  10. Rear Quarter Panels

Because this is going to require such an enormous amount of material and consumables, I’m planning on buying in bulk. It seems like the biggest savings from buying in bulk will come from the carbon fabric. I’ve been planning on starting out with one 100 yard roll of 3k 5.9oz 2x2. Which raises the question, will that be a good thickness to produce all of these parts? I’m still a little vague on how many layers, on average, all of these parts will take. In the Easy Composites hood video, they only used two layers, but the second layer was much thicker than the outer layer for the top part of their hood.

Would using 3 or more layers of 5.9oz fabric increase the risk of failure for vacuum infusion compared to only two layers?

How many layers of 5.9oz fabric can be used in infusion for a part the size of a car hood? It seems to me that eventually it could be too thick for the resin to penetrate all of the layers.

#2

I’ve compiled a list of the tools and materials I believe I’ll need, as well as the rough costs for most of the things. Quotes are from various websites as notes to myself:

TOOLS
Gel Coat Cup Gun - $131

Paint spray gun with 2mm tip - $32

Air compressor - ~$300

Mold release wedges - $Various

Scale - ~$30

Large table with a stick resistant top.
“I use a 3/4 in. thick 4x8 sheet of melamine covered fiberboard on top of saw horses. You can get one for $25 at Home Depot or Lowes. This works extremely well as it is cheap, large and very resistant to stick. It is also pretty durable and double sided which is great as the table will take a serious beating.”

Tarp to cover the ground as it will be covered in resin

Scissors

Tin Snips

Circular Material Cutter w/extra blades - $12

Squeeze dispenser for polyester resin catalyst

Composite rollers - $Various

Body filler spreaders - 200 for ~$40

Rivet gun

Hot melt glue gun

Vacuum attachment for bagging

Vacuum pump - $255

Resin catch pot - $120

Line clamps - $7/ea

Pump oil - $7

Infusion connectors - $5/ea

#3

[FONT=Calibri][SIZE=4]CONSUMABLES
Modeling clay - 8lbs for $31

Fiberglass Chop Strand Mat (CSM) - 1.5oz @ 50" $3.50/yd

Polyester Resin - $137

Polyester Gel Coat - $250

Tongue depressors

Cup gun cups - $0.53/ea

Sand paper (wet 240 and 400 grit)

Sanding block

Masking tape (3/4" and 2")

Dremel - ~$45

Acetone (cleanup)

Aluminum flanging materials
“I like the 50 foot .016x6” roll I get from McMaster-Car and also use .040 sheet and cut with pneumatic sheers for places that require stiffer flanges"

Aluminum angle stock
“I like to use the 1/16” thick 1x1" and 2x2" 90 deg angles because I can cut it with snips"

Rivets 1/8" aluminum 1/2" long
“I love rivets as you will soon see”

Hot Melt glue gun sticks
“the best of these I have found are the ‘High Strength long cure’ variety sold at Home Depot”

Part-All #2 Release wax - $28.75
http://www.carbonfiberglass.com/Supplies-Tools/Mold-Release-Wax/Partall-2-Paste-Wax-7lb-tub.html

PVA (poly vinyl alcohol) - $17.50
http://www.carbonfiberglass.com/Supplies-Tools/Mold-Release-Wax/PVA-10-Moldrelease-Gallon.html

PTFE Release agent - $126/case

Nitrile rubber gloves

Carbon Fiber fabric - 50" @ 100 yards ~$2,000

Nomex Honeycomb Core
“1/8” – 1/2" thick 3.0 lb./sq ft. depending on part. AVT is my source for honeycomb”

Perforated release film - $5.50/yd

Breather Ply - $4/yd

High elongation bagging film - $4.40/yd

Bag sealing tape - $6.95/25’ roll

Epoxy Resin - $128/2gal
“I use the medium cure thin from US Composites for most of my parts and I have been happy with it”

[/FONT][/SIZE]
Anything I forgot? Anything I listed that has a better alternative? I made this list a while back and didn’t put a whole lot of time into shopping around. I know I can get cheaper vacuum pumps and resin catch pots in the US than at the links I listed. Keeping in mind that I eventually want to make a rear quarter panel for my car, what size vacuum pump should I get?

I’ve attached some pictures of my car so you can see what I’ll be working with. Except for the front bumper, they’re all pretty simple shapes. The factory “diffuser” is the same piece as the bumper. I plan to do a factory diffuser delete and fabricate my own diffuser, so it will look very similar to the one I’ve attached. I will also be upgrading to a single exit titanium exhaust before I do that too, so ignore the factory dual exit you see on my car. Also, I included that first picture specifically so you can see the rear quarter panel. It starts underneat the door right behind the front wheel, travels along underneath the door, forms up the actual quarter panel, then wraps up around over the door, runs alongside the roof above the door, and ends down by the hood and inspection sticker area. Unless those are somehow multiple pieces that just appear to be one, it’s HUGE. And probably welded to the chassis.

#4

You wont need PVA, wax or PTFE. Get a semi permanent to do all the releasing.

The diffuser might be stretching the capabilities of infusion. You might need to “prepreg” the cloth with a spray adhesive. Probably seed some feed lines down the veins so that you dont end up with air pockets at the tips. Someone here with more infusion experience might be able to help though.

#5

Oh, thanks for pointing that out. I actually knew that and that was the plan, thanks to our discussing it in this thread: http://www.compositescentral.com/showthread.php?t=8471

I made this list long before starting that thread and haven’t updated it since. Even scanning over it today, I didn’t notice that those were still on there.

For the diffuser, I was planning on making several pieces and then bonding them together. For the strakes, the first idea that came to me was making a 90 degree angle at the top of them. I was thinking I could then cut slits in the main piece and slide the strakes through them so that the 90 degree flaps would be on the top side of the diffuser, and I could use a bonding agent on the top between the flap and the main piece of the diffuser itself. I hope I explained that well enough.

Another thing about the diffuser is that I’d like to make it curve up in the back like a Ferrari instead of a hard angle which, to me, seems like would be more likely to create turbulence. At the end of the day, I’ll really never know if my home made diffuser is actually functional (or maybe even counterproductive) but I figured absolute worst case scenario: it’ll look cool.

#6

I would think replacing most of your cars body panels with carbon would throw the way your car handles a lot. You might have to put some ballast in there to help.
I wish you the best of luck on your business! With time and practice I’m sure you will be fine.

-Tom

#7

Oh, I’m going to completely ruin the almost perfect factory balance of this car. Blasphemous as that is, my main goal of the car is simply to see how light I can make it. Weight reduction is always easier in the back of a front engine car, so it will definitely be nose heavy. I’ll do my best to make up for it with suspension and aerodynamics. I could relocate the battery to the back, but the battery I’m looking at weighs like 3.5lbs.

What do you mean, “ballast?”

#8

^Think corner weighting with lead weights to balance the new characteristics of the lighter car.

#9

Ah, ok. Thanks.

#10

I would start with something small, to make sure you know what you are doing. This will still involve a capital investment of equipment and consumables, but you won’t need to purchase bulk carbon.

Mold making will be the hardest thing to perfect. Start with small parts. Trim, flat panels, etc. Do your layup as needed (gelcoats, part, bagging, etc) and then infuse. Then you will know what you need to perfect for larger items, like a hood. Good luck, and welcome to the love to all things carbon.

#11

I’m always a fan of making lighter composite parts to replace steel parts, but I’m going to bring you down to earth a little. I’m new at making composite parts, but auto restoration and customizing is my business.
I would take 9 and 10 off the list. The quarters and roof aren’t just “welded to the body” like an old frame based car, they ARE the body. It’s a complicated structure of interlocking panels and braces, probably strengthened with epoxy adhesives. If you were to replace the outer skins with CF, you will have a big challenge just getting a good bond to the rest of the body. The next problem will be that the CF and the steel will have completely different flex and resonance characteristics. One or both will fail structurally. There are a couple cars out there with CF panels integrated into a steel unibody, (BMW m6) but they designed the steel body with that in mind. If you want a CF car body, build a whole Composite body.
Ok, back to the part of your plan that is possible, I would recommend hood, fenders, trunk lid, then bumpers. You may find it difficult to make the “bumpers” (actually bumper covers) much lighter than the plastic they are already made of, but you can always make them look cooler:)
Diffusers look great, but don’t worry much about function, they aren’t going to make much difference without underbody fairings.
Hoods and fenders are relatively easy and add little to the structure of the car.
I would still start smaller with some interior pieces to hone your skills. Dash tops, door sills, etc are good starter projects. My first composite project is a headliner trim.
BTW, I’m a big fan of the new brz/ frs but you might want to save some of that cash for some nitrous or turbo kit, not the fastest cars around.
Look foward to seeing your work!

#12

Not sure if this project was ever completed, but this thread may help you.

http://forums.corral.net/forums/lounge/660756-sub-2500-lbs-96-mustang-cobra-project.html

#13

Thanks. That is a huge thread so there’s undoubtedly some good information in there. Only the pictures from the first post are showing up here at work, so I’ll have to look at it later.

#14

As for making thicker carbon parts, usually the first layer is 5.7 oz/ft2 carbon (or slightly heavier, to get a more dense carbon) and the rest is multiaxial or heavy woven, which is a lot cheaper.

Another option to bulk things up are glass, and Coremat / Soric (depending on your process)

#15

Would those options be light though?

#16

All depends what you are looking for. Thickness should be enough to create the stiffness needed to not deform the part under load. Local strength should be enough to withstand forces from mounting points.

You will Always have areas that need beefing up.

Besides that, 1 layer of 5.7oz carbon will bring about nothing. You need beefing up anyhow.

#17

I’m looking for as light as possible and being able to withstand 140mph winds. So I was thinking maybe 3-5 layers of 5.7oz.

What do you mean it will bring about nothing?

#18

1 layer of 5.7oz is too thin to withstand wind forces.

For instance 5 layers, that will be some 1.5mm (1/16") thick.

Price: (sorry, in Euros)
5x18 euro = 90 euro

When 1 layer of 5.7oz and 2x 12oz multiaxial
1x18 euro
2x20 euro
total = 58 euro

You already saved 32 euro / m2, just by choosing different materials for the back fill… Not counting processing advantages

#19

Ah, ok. Thanks.

#20

I’m guessing this would be your very first time working with composites?

I can’t add much except to expand on the previous advice to start off with some smaller test pieces first. Even though you want to end up using infusion I’d also say that it’s a very good idea to start off making some things using wet layup - start at the most basic technique and build your knowledge & experience from there.

Maybe start off with a couple of household items since you’re interested in that as well? I’m thinking I’ll be making some concrete items in the future… they seem to be getting plenty of love on Instructables.com at the moment. (Just mentioned as an addition for something that could be suited for use in household items, composites aren’t limited to just fibreglass and carbon fibre!)

It’s great that you have spent so much time researching and learning all you can, the internet is a great resource for that - but you’ll probably find that you lean even more with the first items/parts you make!