Carbon Fiber Bodywork

lemme look when i get some time this weekend..maybe later...i may have one

what yr.......

78 A2....but I think I want to try and copy the OEM right sidecover I have first. I have a little more experience now, and I have a few ideas I'd like to try with the OEM mounting.

I mixed up a small batch of epoxy resin, then added 20% graphite powder by weight. I thought it might be a little more transleucent than this

but hey, it should do it's job....I hope. Another little experiment I tried was to omit the use of PVA. No matter how fine I spray it, it imparts an orange peel finish to the mold, which then needs to be sanded out. Instead, I put a handful of coats of mold wax on the tail as the sole release agent. It should cut down on mold refinishing work

I brushed on this first coat of graphite/epoxy, a total weight of 165g of resin. One thing I was surprised to learn was that the packaging tape I use to cover the file folder flange kinda repels the epoxy. This is the first time I didn't use PVA, and the first time I used epoxy as the mold matrix so I shouldn't be suprised that the materials are behaving a little differently

it sure does look nice though. The epoxy I got for making the tank top is perfect for mold making- becasue the viscosity is higher, it covers better

A word about the materials I used on this mold- Of course it's no secret I used graphite powder in the "tooling coat" to increase the durability and slickness of the epoxy, but I had to make a change in the fiberglass reinforcement I used as well. To date, all of my previous molds have been polyester resin based, and I used a combination of chopped strand mat and cloth for reinforcement. Switching to an epoxy resin, I can no longer use the chopped strand mat as it is held together with a styrene adhesive that disolves in the presence of polyester resin. Without the styrene, the mat won't lay down so I had to obtain an alternate heavy reinforcement. I got 2 yards of each 4oz and 24oz fiberglass fabric for this mold

Side by side, it is a signifigant difference. In hind sight, I would rather have used either a lighter cloth than the 24oz or used a lighter resin. The thicker resin I had on hand did a poor job of whetting out the heavy cloth. Another good learning experience

I started with 2 layers of the 4oz which is very light and conforms nicely, then added 2 layers of the 24oz, folloed by an additional 2 layers of 4oz. This is after the last 2 layers of 4oz

The 24oz cloth was so thick and heavy that it would not conform to any corners, so I had to cut it and use it only on the flat ares of the flanges and on top of the tail. Also, I couldn't use sissors to cut it it was so thick. I had to use a rotary blade. Pain in the ass, I probably won't use this stuff again.

Then I added another layer of 24oz and then 2 more layers of 4oz. The mold was semi cured and I had flipped it over to strip out the flange. Thats when I discovered that it wouldn't stay where I put it, it would just roll over to one side. So, I cut a couple pieces of 2.4 and glassed them across the front of the mold. That way there is something flat to keep the mold from rolling side to side. Here is the completed mold being cured by a little space heater I use for just such an occasion

Patience is a virtue....one that I seldom posses. But lets start with the good points first, shall we? I am happy to say that the tail popped out fairly easy, and the mold finish retains the matte look of the 600 grit that I final sanded the tail with. So no orange peal from PVA and easy release with just mold wax....thats one step removed from my previous procedure. Now for the lesson on patience Early readers will remember that on my first mold, I was a little hasty with my application of fiberglass after brushing on the first mold coat of resin. This resulted in air pockets on the mold surface. I vowed never to make that mistake again......until yesterday :S
I had brushed on the tooling coat and allowed it to get tacky, but by no means cured. I was a little ancy, so I thought it would be safe to start adding layers of fiberglass. I was correct in my assumpion that it was safe, until I layed a layer of cloth down incorrectly across the top of the tail. No biggie I though, I'll just pull it back up and re-lay it. BIG mistake! While I couldn't see it, when I pulled the cloth back up (it stuck REALLY well) the surface coatof resin separated from the mold surface a bit, creating some air pockets. I should have brushed on more resin, then relayed the cloth and rolled it, but I didn't. I just kept on going. So, a word of warning- if you need to disturb a layer of reinforcement on a tacky tooling coat, be sure to add more resin and roll it good to get any entrapped air out.

Luckily, the defects are confined to the top of the tail, the easiest area to access and repair. Everything else looks good. I'll fill the pin holes/bubbles and start working on wet sanding the mold interior with 1500 in preparation for polishing. I am curious to see how hard it will be to sand with the 20% graphite :blink:

more,more,more,more, .
sorry to say adam,that i for one am glad that your project gave you a coupla days off:laugh: .just being selfish,i know you need the cash.but the L.O.S. was sure jonesing for an update with some real content.
keep us posted,

leon

Hey Leon, hows your injuries healing up? I must agree on the break as well. I went from 15hrs a week to 65. You get a little soft, hanging around the garage and playing with the kids most of the day. But I came back with some worthwhile progress.

I think I may have lost a couple readers with my less than professional questioning of the eBay seller with the carbon bodywork. FWIW, for anyone put off by it, I sent the guy an apology and wished him luck. I have no business standing on a soapbox with all my failures. :blush:

Tonight I'll get the mold trimmed and cleaned out of any primer stuck and remaining clay. If I have time I'll mix up some graphite/epoxy and fill in those bubbles. If I can get the prep time in, I might be able to make a tail next weekend

if you got to time to send sorry notes to complete strangers....


then your ass better have time to show us some finished product before santa leaves the lump of coal in your tank!!!!

artists are allowed a little leeway

trianglelaguna wrote:

if you got to time to send sorry notes to complete strangers....


then your ass better have time to show us some finished product before santa leaves the lump of coal in your tank!!!!

X2
Can I get an Amenahhhhhh?
Can I get a Hallelujahhhhhhh?
(use your best James Brown impression)

Artist alientech? I am just a copy cat hack from where I sit. I am comfortable with numbers, geometry, logic....I do not posses the gift of abstract creation like a true artist