Fibreglassing expertise needed

[bogan]

I'm after some fiberglass mat and resin etc for some custom bodywork. However the design is fiberglass reinforced thermoplastic. I've made some CNC male molds in mdf and in the process of pulling the plastic shells off them (get a really good outer surface finish and precision this way). Size is a large cowl, and largish tyre hugger. Because the fiberglass will be laid on the inside, and stay stuck to the plastic, I don't need to worry about release agents etc.

So what is a good type to use? how much should I expect to need? and where is a good place to get it from?

here's a pic of the mold

[Madness]

Fibreglass Developments in Bunnythorpe are a good bunch of buggers, FWIW.

[bogan]

Fibreglass Developments in Bunnythorpe are a good bunch of buggers, FWIW.

might have a chat if I can't get computer-fed advice, don't really wanna go take up professionals time for such a small project.

[Grubber]

I'm after some fiberglass mat and resin etc for some custom bodywork. However the design is fiberglass reinforced thermoplastic. I've made some CNC male molds in mdf and in the process of pulling the plastic shells off them (get a really good outer surface finish and precision this way). Size is a large cowl, and largish tyre hugger. Because the fiberglass will be laid on the inside, and stay stuck to the plastic, I don't need to worry about release agents etc.

So what is a good type to use? how much should I expect to need? and where is a good place to get it from?

here's a pic of the mold

Jeez your keen. Do a bit of my own paint and panel work but i'm not that into it i'd make my own molds though. Well done.
I know a guy out in Waiuku that does a lot of that type of work might be able to help.Not sure! Will PM his number for ya.

[CookMySock]

[...] Because the fiberglass will be laid on the inside, and stay stuck to the plastic, I don't need to worry about release agents etc.

Almost any fibreglassing product will do that. The hardest part will be getting it all lay down flat and smooth.

I'd look at using a cheapo basic epoxy resin, fibreglass cloth, peel ply, and vacuum bag the whole thing just enough to hold it all flat while it cures.

Epoxy coz it doesn't go off hell-quick while you are trying to juggle it all into place, and sometimes polyester stays soft for days in the cooler weather. Also some polyester is hard on some plastics, especially foamed plastics.

Cloth coz it gives a better finish - BUT you will have to cut lots of bits up and lay it into corners on the 45 degree weave to get it lay down. Spend lots of time planning before you start catalyzing resin.

Peel ply coz it just leaves a wikid az finish and its fun. You can raid your mrs' sewing bag of tricks for cloth to be used as peel ply. Any strong thin nylon/rayon-sorta fabric that goes zzzzzzip! when you run your fingernail across it will do.

Vacuum Bag coz thats about the only way you are going to get it to lay flat unless you grow another four arms.

Search youtube for bagging howto vids, and google any terms you are not familiar with, as ya do.

[bogan]

My research reckons that I need 4.5m2 of powder bound CSM, and a 5L epoxy resin kit. Be putting an order in over the next few days, so if I am wrong, or if I need more shit, please let me know!

[CookMySock]

It isn't that CSM is "wrong", it's just that cloth makes a tidier more rewarding job and looks cool. CSM layups are like trying to shape mashed potato with chicken wire in it, whereas cloth layups pack down flat and hard.

5L sounds like a lot of resin. My guess is you won't use 1/4 of that. Remember the goal is to use the minimum possible amount of resin, and pack it all down really harrrrd, but without air bubbles.

If you do use polyester, keep your layups thin, mix small amounts of resin at a time, and keep your ambient temps down, and be ready to move fast if it starts to set. Expect to have to warm the job the next day because it didn't properly go off. You need a lot of experience to work with polyester coz it can get cranky on you with little warning. Epoxy is much more predictable, and if it's not then at least it doesn't go thermonuclear on you without warning.

Also strongly recommend you do some initial practice layups on a discarded ice cream container, to get the hang of internal and external corner layups, or else you might end up with your very cool work-of-art plug looking like it's been tar and feathered!

And have fun! FRP is cool!

[imdying]

My research reckons that I need 4.5m2 of powder bound CSM, and a 5L epoxy resin kit. Be putting an order in over the next few days, so if I am wrong, or if I need more shit, please let me know!

You want about a 450gsm CSM. 5 litres should be heaps. Get a metre of woven cloth to put on the inside to tidy it up.

If you do use polyester, keep your layups thin, mix small amounts of resin at a time, and keep your ambient temps down, and be ready to move fast if it starts to set. Expect to have to warm the job the next day because it didn't properly go off. You need a lot of experience to work with polyester coz it can get cranky on you with little warning. Epoxy is much more predictable, and if it's not then at least it doesn't go thermonuclear on you without warning.

I think you've got them backwards mate.

Get some scales to measure your epoxy out on, it can set itself on fire if you mix it wrong, or try to mix up too much. Make sure you have somewhere to put your resin mixing container if it goes bad; I try to have a bucket with sand in it handy.

[bogan]

sounds like a plan, will add the cloth and put an order in.

Tell me more about this resin mixing, have got scales etc, how much do you think is a good amount to mix at a time? The resin is the most expensive bit and I'd rather not waste it...

[imdying]

Tell me more about this resin mixing, have got scales etc, how much do you think is a good amount to mix at a time? The resin is the most expensive bit and I'd rather not waste it...

The product will come with a datasheet, you can't go wrong.

Resin/fibre ration is about 50/50, so if you're doing it right you'll use about 300gm of resin for a square metre of 300gsm CSM. You'll probably use more, but some of that will be excess left on your tools/work surface, plus you won't get a perfect fibre/resin ration without bagging it.

Make sure you have acetone on hand to clean things with. Get a couple of tall glass (pasta) jars to leave your brushes/rollers in.

It's dead easy, a three year old could glass shit up, you really can't go wrong.

[imdying]

That thing you've built... I would cover it in body filler, sand it back to about 120, shoot a thick layer of Duratec Surfacing primer (get it from Nuplex) over it, polish that to 2000 grit, flange the edges, flange it up the centre, mould one side, mould the other (make the centre flange bolt together, put some alignment lugs on it), then make a one piece tail from that. If you're not super anal about the surface (given you can sand the final part easily enough) then it's a piece of piss.

[bogan]

That thing you've built... I would cover it in body filler, sand it back to about 120, shoot a thick layer of Duratec Surfacing primer (get it from Nuplex) over it, polish that to 2000 grit, flange the edges, flange it up the centre, mould one side, mould the other (make the centre flange bolt together, put some alignment lugs on it), then make a one piece tail from that. If you're not super anal about the surface (given you can sand the final part easily enough) then it's a piece of piss.

Yeh that sounds like the way it's usually done, but I reckon having a thermoplastic shell reinforced with fiberglass makes one-off a lot easier and quicker to produce. Also the guy/owner I flat with has a phobia about fibreglass sanding (among other things).

[CookMySock]

I think you've got them backwards mate.

[imdying]

Yeh that sounds like the way it's usually done, but I reckon having a thermoplastic shell reinforced with fiberglass makes one-off a lot easier and quicker to produce.

Sounds like fun to fix too.

Also the guy/owner I flat with has a phobia about fibreglass sanding (among other things).

So, he's not sanding them is he? If you don't like sanding, stay the fuck away from eglass work

[bogan]

Sounds like fun to fix too.

Fix? I don't plan on breaking them

So, he's not sanding them is he? If you don't like sanding, stay the fuck away from eglass work

But it's airborne, I mean, that stuff is pretty much over the counter agent orange