Fiberglass help needed

[don911]

I'm trying to make some splitters out of FG. the shape is molded on the car and I have a layer of duct tape finishing the shape.
I tried laying up some fg but cant get the strips to stay down. I cut the fg in strips to mold the shape but they won't stay in place and also don't form the shape very well.

This is my first play at fg. Any experts out there? Below is what I'm trying to fg. Thanks.

[Buckterrier]

Don, I'm sure it was but was the cloth saturated in the resin?

[don911]

yes the cloth was saturated. It kept sliding around and coming up. I don't know if I had too much resin or not enough.

[URY914]

Using f/g in direct contact with duct tape is a bad idea first off. The heat from the reaction will melt the adheieve in the tape and cause it to move on you.

Try a sample mix to get the ratio correct.

Are you using mat of cloth? A heavy mat may not bend to the shape you want.

[URY914]

Are you tring to cover the duct tape mold with f/g?

[don911]

yes, the silver in picture is the duct tape. I'm using fiberglass cloth. I cut it into strips to try and form the shape. I tried two test areas and both times the cloth keep moving around and coming up off the mold. I thought it would stay in place better. I might have to take the valance off the car and so the part is vertical.

[Buckterrier]

I think that's the problem, going over the duct tape. btw, it's a gorgeous splitter

[Jerome74911S]

I'm no expert and others may offer better advice, but you might do a search into the techniques used for amateur-built aircraft. There is a method using a "peel ply" of (I think) thin rayon fabric that goes over the glass to keep the surface and shape correct. When the resin is fully set, the fabric gets peeled off. Aircraft have to have shapes and surfaces that are really accurate and this technique has been around for quite a while. Take a look at the EAA (Experimental Aircraft Association) website. I didn't check it, but would not be surprised if you find a useful link there.

Jerome

[don911]

Originally Posted by Buckterrier

I think that's the problem, going over the duct tape. btw, it's a gorgeous splitter

Thanks, the splitter may be all for not if fiberglass wont stick to it. I used duct tape because it formed the shape well and I thought also had built in mold release.

[Flieger]

+1 on Peel Ply.

Use fiberglass fluff- not fabric. Wet it enough to get it cohesive and you will be able to mold a layer or two. Then come back with the cloth.

Cotton also works with the resin as an intial shaping layer.

[Buckterrier]

Don, are you just trying to make a mold for more splitters? You could use thickened epoxy for that I'd think.

[don911]

Originally Posted by Buckterrier

Don, are you just trying to make a mold for more splitters? You could use thickened epoxy for that I'd think.

My first "plan" was to make a mold from the shape on the car. I made a plaster mold of the shape last night. Because of the curve/shape, casting material became an issue so I decided to try to make the part from the shape on the car.

I'd prefer to make a mold so I could reproduce the part if needed but can't figure out a way to do it.

[stownsen914]

Peel ply is part of a vacuum bagging setup. Vacuum bagging will certainly fix this issue, but there's a lot more to it ... vacuum pump, fittings, mastic tape. You can learn more about that at aircraftspruce.com if you're interested.

Vacuum bagging may not be necessary though. As Paul suggests, try a lighter fiberglass cloth - it will conform to the curves and angles better. You can also try using gel coat. It's thick and you can build it up in the crevices where the mat lifts away a little.

Scott

[URY914]

You can also thicken your resin by adding bits of f/g to it. Cut some of the cloth/mat with sissors in very small pieces and add it to the resin. A boating supply store will also sell this as "filler".

[toddc]

--Been doing this for about 20 yrs but before offering any advice I'd like to know more about what you're trying to accomplish and what you're using for materials. Feel free to pm me.
teaser pic is no porsche content but it's cool... 1 lb carbon fenders, audi rs4

todd

[nineball]

fg does not stick to ducttape, at least from my experiences. check out Fiberglass Forums - Powered by vBulletin for a lot of great info. it is mostly centered around car audio related projects but the fg basics are all covered there as well as hundreds of threads with build pics for just about every surface inside a car, and a lot of exterior as well.

[don911]

Thanks for all of the help. I put a layer of just resin on last night but it's not very thick. I'm going to cut up some cloth and make thick resin/fg mix as suggested and do another coat. If I can get a decent thickness, it may pop off and I can use it to make a mold of the shape. If I can get a good mold I can lay it up off the car.

btw - I'm trying to make splitters similar to these for my 930S valance.
FS carbon brake ducts and 3.8 splitters

[avendlerdp]

It looks like you might be able to make a one off of that part by just glassing over it and then removing and finishing your part on a bench.

Here is a basic plan that will get you there.

Jack up car as high as possible for access.

Clean painted surface and apply mold release wax all over in a couple of layers.

Tape off parts you don't want to mess up.

Use EPOXY RESIN to make your part. Epoxy resin is less likely to damage paint on the original part. Use 2oz cloth or lighter for first layer. Use very little resin so there are no pools and runs. You will need soft plastic squeegees and spreaders. Epoxy had a long pot time so take it slow. You can hold sections of stubborn cloth down with masking tape.

Add a couple more layers of thin cloth.

Carefully pop off your new part. Compressed air make this easier.

Trim part to size and add more layers for strength with part mounted on a bench.

Sand and finish.

Enjoy a beer and marvel at your new part.

I know it seems nutty to use the bare car as a mold but covering it with tape will cause the cloth to slip off it and not actually give you a shape you want.