I want to make a different style of rear wheel arch out of fibreglass but am not sure where to start.

I was thinking along the lines of making the rough shape with chicken wire/mesh, covering with paper mache and then fibreglass over the top.

Would this work ok?

Is this to make a buck to take a mould from or for the real thing?

I would fabricate something of hard foam rather then paper mache.

A friend built GRP boats, he built his moulds using a hardwood frame and hardboard to get a smooth as glass finish. The mould is everything.

I used to have the rare job of making theme park rides, we did all sorts of random fibre products as you can imagine. This was a few years ago though so I shall cast my mind back.

method 1

Make the shape you require out of chicken wire and modeling clay. This clay can be bought in big ready mixed bags. Then gel coat/glass over this making yourself a mold. When the clay is scooped out of hardened glass you will be left with a reverse of your part. This can then be waxed and then glassed into again. When its hard they can be taken apart and you still have a mould and the part.

Method 2

Sculpt the part shape from foam. Either the denser foam as mention earlier or polystyrene (packing foam often white). Then cover the object in tin foil and then glass over it. Careful not to get resin on the foam as it melts it into a horrible gloop. The tin foil acts as a barrier. When set scoop the foam out with fingers/knives/saws/blades/teeth and you are left with the desire shape - this method leaves a rather untidy finish that will need filling and sanding that will take ages.

I have never used paper mache cept when making a blue-peter style money box

I hope this helps

Ok, seems alot more hard work than i thought.

I will be making three parts. Left rear wing, right rear wing and a (rather large) bonnet.
Method 2 makes more sense for one offs but method 1 seems easier.

Probably go with method 1

hi
I am just in the proccess of finishing the last of my mouldings (rear wings)
I would suggest if this is yout first attempt at fibre glassing start with a practice piece (i made a silencer guard first).
I found the secret is to make a plug that you can finish to a high gloss being well sealed with shelac and polished with a good quality carnuba wax polish (I used Maqiures but it is rather expensive.)
Then sparingly coated with a PVA release agent.
This should produce a good mould for the finished product.
I found it was not cheap and very time consuming but very satisfying when you get it right!!!!
I was lucky in getting the advise of an ex employee of TVR/
I wish you the best of luck

Cheers

Keith

One method I use for making a plug is to cut the shape out of MDF , in as many parts as it takes , glue/screw it all together , and then sand whatever shapes you cant get by cutting .
Next - apply body filler where needed , to get the shape right , and paint with a high build polyester spray filler . Finish this with 1200 wet`n`dry , wax , and then make the mold .
It's one thing to make the bits as total one-offs , but if you have the misfortune to damage them once you are on the road ..........

I just want you to know my own experiences are just that, but after trying for almost 3 years off and on, I have yet to make a nice piece of fibreglass. I can't seem to get the mix of hardener right, or the mix of epoxy, so it never hardens enough or too fast. It is really really hard to get right, and I just don't have it. I am also a little tired of the headaches associated with the resin. Epoxy doesn't smell as bad.

RK, you just need some dispenser pumps to go on your epoxy bottles, they dispense the exact amount of resin and hardener. As long as you mix it thoroughly you cant go wrong. As to polyester resin (styrene) fumes, they are extremely toxic and if you're getting a headache from it, you are working in an inadequately ventilated area. Avoid this with any type of resin, even epoxy. You can't smell epoxy fumes but they're supposedly worse than polyester.

Speedyxjs, unfortunately there is no short cut to making good composite parts. You need to do some learning first about the materials and then as gy351100 suggests, make some smaller parts first to get the hang of it.

As far as moulds go, making a male or female mould will be equally time consuming in the end. You either put in the time to make a plug hen a mould. Or cast over a shape and then have the dull and messy task of creating a finish on it that won't look like crumpled Harris Tweed In my experience, a mirror finish mould isn't essential if you plan to paint the finished piece. Even a visible carbon fibre look can be sorted out with clear coating, provided you get your resin/cloth ratio correct.

Anyone considering the dispensing pumps, don't bother! Everything becomes a horrible sticky mess.

I know I am doing something wrong, somewhere, but it hasn't been worth the effort for me. It is too hard to judge the amount of hardener in polystyrene, and you really need a scale to measure the amount of epoxy if you're doing that - and even then.

As for fumes, I'm doing it in a double garage with a fan and the door open. Can't get much more ventilated than that, and the garage smells to high heaven for weeks afterwards.

I'm just passing on my own experiences. It is expensive too when you add it all up. Your results may be better and I wish anybody else the best of luck!

These demo videos you seen around are obviously of David Copperfield in disguise.

Argh yer see it's one of them there "black arts" but when you know it's really quite easy but plug work takes an age to do

I am very happy the wee man is in Cornwall making all the fibreglass we will all need!! Keep it up Mark!

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It is too hard to judge the amount of hardener in polystyrene,

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