Fibreglassing tips and hints thread

I thought we should get a thread going on fibreglassing.

Has anyone noticed that a perfectly flat fibreglassed panel will distort and bend after a while? Do you know why this is and how it can be avoided?

Does the quality of materials have much to do with the quality of the finish?

 

[old-git]

All flat panels, no matter what materials they are made of, will distort unless properly supported or reinforced. That is why flat metal sheets often have grooves (can't think of the correct word at this time of night) pressed into them - to give them strength and to resist warping.

If you want to prevent a flat panel from warping, either make it thicker, add reinforcement to the back (both add weight) or, if possible, give it a slight curve.

Carbon fibre can be made less susceptible to warping by alternating the direction of the weave layers (a bit like plywood sheets). As normal chopped fibre glass has no weave this isn't possible. However, if you use the fibreglass woven mats these may be less prone to warping, but I have no experience of this material.

 

[teaszer]

Just the thread i am looking for.
I am looking to sort myself out a bumper for the rear of my polo.
I am planning on taking off the standard rear bumper. Building one in carboard and ductape then im going to use that as a template and cover it in fiberglass then go over that with body filler and then paint it.
Mainly i would do this to my taste of style as the bumpers i see online i dont really like too much.
What do you think :bigsmile:

 

[pgarner]

why not vist a scrappy and get a rear bumper and use that as your template ? this way youll still have all the mounting points.

wouldnt advise trying to start on something as big as a bumper without hveing alot of fiberglass practice

 

[MasterAuron]

Just the thread i am looking for.
I am looking to sort myself out a bumper for the rear of my polo.
I am planning on taking off the standard rear bumper. Building one in carboard and ductape then im going to use that as a template and cover it in fiberglass then go over that with body filler and then paint it.
Mainly i would do this to my taste of style as the bumpers i see online i dont really like too much.
What do you think :bigsmile:

Agree with what PGarner says really. You'll really struggle to get the cardboard out of the mold once it's dry even with plenty of releasing agent. And you can't just fibreglass over something then use that bcause it'll be bigger! You need to make a mould first then fibreglass into your mould.

 

[teaszer]

Very true.
How much fiberglass do you reckon this would need. The bumper is quite small its only going onto a mk4 polo

 

[weber44idf]

you will need

fiberglass resin ( mixed with hardener to wet out the glass )
choped strand mat ( for high load areas )
glass tissue paper ( tight corners etc )
woven mat ( main parts of the glass work - bulk )
foam sandwich ( cut up & bend to form the shapes required )
acetone ( cleaning agent )
mekp-sr ( hardener )
q cells or simular ( filler to form the radius and smoth the form )
additionally a glass roller , stiff paint brush and icecream containers
you will need to talk to the local fiberglass suppliers / fabricators in your area , not a bad idea to offer a bit of free labor & learn how to actually do the job , just be aware that the majority use a chopper gun in their manufacturing process not hand lay as you will . also they make a plug from the item the want to produce then lay the plug / mold up to produce muliple items . i can only say good luck as the scope of work is quite big and getting things symetrical is a must .

 

[pgarner]

depends on how mental you want the bumper to be.
have a look here http://stores.ebay.co.uk/Fibreglass-Supplies-UK
i have used them myself and i belve old git on here has also used them