anyone used fibre glass and resin?
 

can you advise me how to use fibre glass and resin?

I have a piece for fibre glass about 9x3 inches. I want to stick it across a split on an undertray. how much resin do I need?. do I put resin on both sides of fibre glass

Do I just put one piece on, let it dry then add another bit let it dry and so on or put multiple layers on at once?

I understand 1 % hardner to resin

macafee2

The way I normally use glass fibre is to wet the area with resin mix, lay a layer of glass cloth, brush in more resin to wet the cloth on the top side and a second layer of cloth followed by further resin being brushed in. This is for model boats.

For an undertray, you will probably want 2-3 layers of thick glass cloth for the strength.

Mix only enough resin for each coat and have a few brushes as you will get through more than one.


You may ant to use 2-part epoxy "resin" as opposed to normal resin if the base material is plastic.

If it was me, I would rough around the area that you will be applying it to, also drilling holes around it. The holes will be covered with your matting, but it will give the resin a different plane to adhere to, maybe even adding a a couple of old 1/4 inch screws or bolts and mat over those too. With it being effectively a flat sheet of plastic you are matting onto, without the above, any flex will allow it to vibrate or peel off. Because of this, I would also reduce very slightly the amount of hardener for this application. It takes much longer to 'go off', however I found it meant the repair was more flexible.

Jim Jamieson repaired his during his brilliantly illustrated suspension overhaul HERE

If we can get it pony expressed to you I've got a load of structural adhesive that should fix the crack. Rough the surface, run a bead along the split and it should hold well.

Alternatively to fibre glass it I'd rough the surface, brush some resin on, put a sheet of thick mat (about 400gsm is what I tend to use), then brush more resin on top, and keep layering mat on top. If you want some added strength you could add a couple of rods of something. When making a ramp for a moped we used an old warehouse shelving rail sandwiched between the sheets of fibreglass to give it strength.

that's very kind of you. my sister lives in Peterborough and we see her from time to time, I could ask her to pick it up.

macfee2

Yea that could work. I'll find out tomorrow which is the best 1 for that sort of repair, we do 2, 1 is for building work, the other is used in automotive industry, but I can't remember which is which. I'll warn you, it stinks so you'd better do it outside!

It may help you when thinking about fibreglass to not think of the resin as glue. The resin is the solid structure and the fibreglass matting is the reinforcement. Rather like reinforced concrete (resin = concrete, fibreglass =rebar). The fibreglass should be sodden with resin and should be applied in layers with curing time between layers. Each layer needs to be compressed as tightly as possible to the previous one for the most strength. As already mentioned it's not going to just stick to any old plastic. Putting screws through so that the resin hardens around them is you best chance of a successful repair. I'm not sure I'd try to repair the undertray this way...

Just another thought, depending on where exactly its split, couldn't you get a metal plate or strip, put it over the crack, then drill through the undertray and the plate, and then rivet the 2 together?

oh, I did think it a bit of a glue.
How would you do it?

macafee2

seeing Avulon's post you might be right.

Time it seems for me to have a rethink. Glad I asked for help as I was going off half cocked

macafee2