Composites 101: Carbon Fiber, Fiberglass, etc.

[B.Curvin]

This is the kind of post that keeps me here.

I'll be using a lot of info from this if I decide to make a new tank for my Buell.

I used to build racing sailboats but that was years ago when I was a teenager. This refresher was great.

Have you researched what kind of sealer would be needed to make something ethanol proof?

[Pike Bishop]

Here are some excellent online user guides from West System epoxy:

http://www.westsystem.com/ss/use-guides/

And here's a link to EPOXYWORKS magazine:

http://www.epoxyworks.com/

Although there are (slightly) cheaper epoxies than West, I've stuck with them for 20 years or more simply because they really are a class act. Their R&D is superb, and you can call them on the phone with just about any harebrained question and they'll patiently do their best to answer it (or tell you if they don't know).

I have no financial connection to them but they're a good outfit.

[Sir Not Appearing]

At the beginning of last school year, I had just been called back in late July and moved to the high school with little time to redo the curriculum. One of my assigned classes was a thinly disguised 1950's Metals class that they were calling "Manufacturing". I was met with blank stares on the first day when I showed the students the projects the teacher had done the year before. I had to think quick and come up with something and nothing works with high school boys like speed and competition.....

I started thinking and remembered that I wanted to learn how to work with fiberglass myself, so I decided that I would introduce composites and plastics into the "Manufacturing" class. I decided we would be building fiberglass-bodied, rocket powered cars with ABS-plastic chassis that would be raced on a 300ft track outside. After I built a prototype and test fired it a few times, the kids were instantly pumped about the project.

Since we were working with limited time, limited budget and each student was only making one project, I decided to use the lost foam method. I had seen some posts on R/C forums (another hobby of mine) where guys made boat hulls and airplane fuselages using this method.

A very quick version of how we did it:

• Cut, glued and sanded insulation foam (pink or blue, doesn't matter) into shape.
• Covered the foam (except the bottom) with a layer of cheap packaging tape to protect the foam from the resin
• Laid 3 layers of fiberglass
• When cured, turned them over and poured acetone into the bottom
• Pour the foam goop out and prep the bodies for finishing

Here is one of the better ones. Since his pickup had the aerodynamics of a brick, he left the wheel wells closed to help out a little. IIRC, the accelerometer showed that this one was in the 40mph range, however we had some in the 60mph range.



The Batmobile-esque car in the foreground took lots and lots of time carving, sanding, shaping, etc. and I wish I had a better pic:



Sure, its not motorcycles but the lost foam technique can be used for pretty much any application where you only want to make one example of the part. I'm going to use it to make some Buell 1125CR-esque pods to hide some of the guts of my naked Ninja 500 that were originally covered by the fairing.

Here is a short but informative article about lost foam technique at Instructables.com.

[HickOnACrick]

Originally Posted by B.Curvin

Have you researched what kind of sealer would be needed to make something ethanol proof?

I haven't looked into that yet. Let us know if you find something.

[HickOnACrick]

Originally Posted by Sir Not Appearing

Here is a short but informative article about lost foam technique at Instructables.com.

Link added to page one.

[Pike Bishop]

Originally Posted by B.Curvin

Have you researched what kind of sealer would be needed to make something ethanol proof?

Have you checked the West System website? I would bet they've been all over that by now.

[P B G]

Originally Posted by B.Curvin

Have you researched what kind of sealer would be needed to make something ethanol proof?

There are always internal sealers such as POR-15 products, or Eastwood products I trust pretty well with undercoatings.

[Flipflop]

There are no resin systems, or coatings for fiberglass fuel tanks that withstand ethanol fuel at this time. Unless you have a fiberglass shell over a polyethylene tank, or metal tank it really just doesn't work when ethanol is in the mix. There are a lot of coatings that work well on metal tanks, to fill seams and rust... but the solvent (ethanol) breaks through and saturates them too, But the surrounding tank doesn't get broken down like it does with a resin based tank.

First off... try not to buy this stuff at retail at the hardware store, or west marine. The markup between a 1 gallon pail at retail, and a drum quantity at a boat building price, you can almost use epoxy for everything... So, find a boat builder near by or look at RAKA, E-bond, and some of the other brands other than West. For polyester look at Ebay, and call around for 5 gallon pails... Should be well under $100 for a 5iver.

The same thing holds true for air rollers, scissors, and paint brushes. (Check bodi.com for the tools. Paint brushes are 18 cents each if you buy a 24 count box...)

PVA is a pain in the butt as a mold release, as it adds texture to the mold that needs to be sanded and buffed out. Mold release wax, works quite well. Honey Wax is what I use, but there are better products.

Duratec makes surfacing primer that are polyester based that builds up quickly, and fills lows. 15-30 mils at one go, use a mil gauge. Go from an 80 grit finish to 800 grit wet sanding paper blocking out the eggshell, then take it to 1000, use a power buffer and buff it to a shine. I like Aquabuff 2000 on a power buffer.

Bondo is not very good for feathering out, the grain size is huge which means it needs to be top coated with other puttys to fill the texture. I do like bondo for rough work, as I don't feel bad about cutting it with catalyzed polyester resin, so that you have a slurry you can paint over open grained and loose structured stuff like drywall mud. (Easy to sand... and cheap!)

Evercoat Rage, or Dynalite pull much smoother without getting into expensive stuff. You might try a finishing coat of 3m Pirannha putty, followed by Evercoat Ultrasmooth putty pulled with a razor blade into pin holes and small scratches.

Sand the plug out with as long of a sanding board as you can use, Use a spray guide coat to find your highs and lows.
If you want to use your west systems to coat the plug, you can greatly speed up the process by using their G5 5 minute epoxy, and the 105/205 system. If you mix the 105/205, and the G5 in their own containers and then mix both together, you can make a thinner consistency product that kicks off a lot faster. A paint brush works to apply, but a squeedgee works nicely to push it into the lows. West system 407 or 410 (Or scotch light microballoons by 3m if you do a lot...) works well in place of polyester filling puttys.

For curves, battens of clean straight grained wood or aluminum bar stock work nicely. Take chalk, pencil, ink... paint... whatever and rub it on the batten, then rub it on the curve. All the highs will show, all the lows will still be clean. Then use the longest battens, straight edges, and sheet rock trowels to pull the putty between them.

Sand with long flexible boards, and on small stuff a paint stirrer wrapped in sandpaper. A body shop supply house can get you the 3m lineup. The red sticky backed inline paper is good for home made boards. 30 inches is about as long as one person can easily apply even pressure to...

Zach

[TheOtherBart]

This is all such awesome information, thanks everybody for contributing.

I've been thinking about laying up a flattrack-style seat for my XR, but I'm too buried in projects to take the time for the whole plug-mold-part thing. Can I get a decent 20-footer by laying the seat right over a foam core? For a seat like that which is going to have some compound curves should I try to use cloth or is mat okay? It seems like mat would be easier to conform to the shape. Then smooth the outside with Bondo, sand, and paint?

[Sir Not Appearing]

Originally Posted by TheOtherBart

I've been thinking about laying up a flattrack-style seat for my XR, but I'm too buried in projects to take the time for the whole plug-mold-part thing. Can I get a decent 20-footer by laying the seat right over a foam core? For a seat like that which is going to have some compound curves should I try to use cloth or is mat okay? It seems like mat would be easier to conform to the shape. Then smooth the outside with Bondo, sand, and paint?

I think for a "one-off" seat, the lost foam method would be a good way to go.

I forgot one of the steps we used when I typed my original post the other night. From my research when I was developing my project above, there was some debate on whether the following technique could cause issues down the road or not. What I had read about online on some forums was the use of 3M #77 spray adhesive when using the lost foam method. So we tried it and had our best success on the vehicles that used it and had some delamination issues between layers on those that were built without it. Here is what we did:

• Build foam mold by cutting, sanding, etc.
• Tape the foam mold on all but one side (in our case the bottom)
• Cut the fiberglass cloth to the size needed
• Spray the taped sides with 3M #77
• Lay the cloth on and use squeegee/bondo spreader to get it tight
• Mix resin and then brush it on
• Cure
• Sand first layer
• Spray with 3M #77
• Lay cloth, add resin and repeat until you have the number of layers you want

I got the idea from R/C sites and this is how some hobbyists do R/C boat hulls and fuselages for planes that have lots of curves. After the last layer was cured and sanded, we applied a very thin “skim coat” of body filler, sanded smooth, sprayed with high-build primer, sanded, painted and clear-coated.

I’m not saying this is the “proper” way, but it worked very well for us and the spray adhesive held the fiberglass to the curves. About half the kids in my 2 classes produced some very nice, slick looking car/truck bodies. If they had been bike parts, they would have been just fine for a 20-footer or better. Also, when we were done racing, about half the students (mostly the not-so-pretty projects) wanted to “crash test” their project so we fired them off at 40-50mph into a curb. Only one had fiberglass damage and they were all disappointed as they expected them to go out in a big cloud of fiberglass dust. Not so…. After 3 layers, they were much stronger than even I expected.

[tmotten]

Loving this thread. Excellent info.

When do people tend to put a skin of fireglass over a plug to reinforce it?

Also, when making a mould is it the exact extent of the plug at the edges, or a little extra (inch or so) to allow for it to be cut?

[HickOnACrick]

Originally Posted by tmotten

Loving this thread. Excellent info.

When do people tend to put a skin of fireglass over a plug to reinforce it?

Also, when making a mould is it the exact extent of the plug at the edges, or a little extra (inch or so) to allow for it to be cut?

I add the fiberglass when the last coat is tacky.

My molds extend beyond the edge of the plug by 3-4 inches. I do this as it makes vacuum bagging easier later

[HickOnACrick]

Originally Posted by Flipflop

There are no resin systems, or coatings for fiberglass fuel tanks that withstand ethanol fuel at this time. Unless you have a fiberglass shell over a polyethylene tank, or metal tank it really just doesn't work when ethanol is in the mix. There are a lot of coatings that work well on metal tanks, to fill seams and rust... but the solvent (ethanol) breaks through and saturates them too, But the surrounding tank doesn't get broken down like it does with a resin based tank.

First off... try not to buy this stuff at retail at the hardware store, or west marine. The markup between a 1 gallon pail at retail, and a drum quantity at a boat building price, you can almost use epoxy for everything... So, find a boat builder near by or look at RAKA, E-bond, and some of the other brands other than West. For polyester look at Ebay, and call around for 5 gallon pails... Should be well under $100 for a 5iver.

The same thing holds true for air rollers, scissors, and paint brushes. (Check bodi.com for the tools. Paint brushes are 18 cents each if you buy a 24 count box...)

PVA is a pain in the butt as a mold release, as it adds texture to the mold that needs to be sanded and buffed out. Mold release wax, works quite well. Honey Wax is what I use, but there are better products.

Duratec makes surfacing primer that are polyester based that builds up quickly, and fills lows. 15-30 mils at one go, use a mil gauge. Go from an 80 grit finish to 800 grit wet sanding paper blocking out the eggshell, then take it to 1000, use a power buffer and buff it to a shine. I like Aquabuff 2000 on a power buffer.

Bondo is not very good for feathering out, the grain size is huge which means it needs to be top coated with other puttys to fill the texture. I do like bondo for rough work, as I don't feel bad about cutting it with catalyzed polyester resin, so that you have a slurry you can paint over open grained and loose structured stuff like drywall mud. (Easy to sand... and cheap!)

Evercoat Rage, or Dynalite pull much smoother without getting into expensive stuff. You might try a finishing coat of 3m Pirannha putty, followed by Evercoat Ultrasmooth putty pulled with a razor blade into pin holes and small scratches.

Sand the plug out with as long of a sanding board as you can use, Use a spray guide coat to find your highs and lows.
If you want to use your west systems to coat the plug, you can greatly speed up the process by using their G5 5 minute epoxy, and the 105/205 system. If you mix the 105/205, and the G5 in their own containers and then mix both together, you can make a thinner consistency product that kicks off a lot faster. A paint brush works to apply, but a squeedgee works nicely to push it into the lows. West system 407 or 410 (Or scotch light microballoons by 3m if you do a lot...) works well in place of polyester filling puttys.

For curves, battens of clean straight grained wood or aluminum bar stock work nicely. Take chalk, pencil, ink... paint... whatever and rub it on the batten, then rub it on the curve. All the highs will show, all the lows will still be clean. Then use the longest battens, straight edges, and sheet rock trowels to pull the putty between them.

Sand with long flexible boards, and on small stuff a paint stirrer wrapped in sandpaper. A body shop supply house can get you the 3m lineup. The red sticky backed inline paper is good for home made boards. 30 inches is about as long as one person can easily apply even pressure to...

Zach

Flipflop,

This is some great information. I was wondering if you can relate any experience you have with the Raka epoxies versus the West System. Raka makes a claim that their epoxies have less cratering and pinpoints when cured, as a result of additives to the epoxies. Do you have any experience with this?

Also, you have given some great information about finishing by using different sanding methods. Do you have links to video to demonstrate these methods?

Thanks again for your great input.

[darenative]

Originally Posted by HickOnACrick

Flipflop,

This is some great information. I was wondering if you can relate any experience you have with the Raka epoxies versus the West System. Raka makes a claim that their epoxies have less cratering and pinpoints when cured, as a result of additives to the epoxies. Do you have any experience with this?

Also, you have given some great information about finishing by using different sanding methods. Do you have links to video to demonstrate these methods?

Thanks again for your great input.

You might want to check out Silvertip epoxy. It is a lower viscosity epoxy and ends up with less surface imperfections and no amine blush. The downside is $$$

[Pike Bishop]

Originally Posted by HickOnACrick

I was wondering if you can relate any experience you have with the Raka epoxies versus the West System.

FWIW, I've used both and find them fairly similar. Raka's cheaper. West has better R&D (and I would say is more consistent).