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Discussion Starter · #1 ·
Anyone know how easy it is to make a small repair to carbon fibre? Nothing major its just one of the spare panels I have has a small hairline crack. I just wanted to strengthen it before it gets any worse. Its about a CM long at the edge, so I wondered if you can get CF repair kits to just strengthen it from the back?
 

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I know a friend, who can do. I'll speak to him tonight
 

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Anyone know how easy it is to make a small repair to carbon fibre?
Much easier to do than on plastic. Just need the resin (SP115) & some 200 gsm CF mat (woven or twill).

Rough up the back a bit with sandpaper, where you're gonna patch it, to help key the bond.
Clean with acetone. Careful with your paint.
A small drizzle of resin in the crack, and apply the impregnated patch on the back for strength.

When the resin is getting tacky, place a piece of shopping bag plastic over the patch, and use your fingers to smooth it off. Remove the plastic when the resin has gone off - 4 - 12 hours dependent on ambient temp.

Bob's your uncle.
 

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Discussion Starter · #5 ·
Much easier to do than on plastic. Just need the resin (SP115) & some 200 gsm CF mat (woven or twill).

Rough up the back a bit with sandpaper, where you're gonna patch it, to help key the bond.
Clean with acetone. Careful with your paint.
A small drizzle of resin in the crack, and apply the impregnated patch on the back for strength.

When the resin is getting tacky, place a piece of shopping bag plastic over the patch, and use your fingers to smooth it off. Remove the plastic when the resin has gone off - 4 - 12 hours dependent on ambient temp.

Bob's your uncle.
Thanks Errol. When you say impregnated patch I assume that just means impregnated with the resin right? Does it need much?
 

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Thanks Errol. When you say impregnated patch I assume that just means impregnated with the resin right? Does it need much?
Yep.
4 layers of 50x50 mm, 200 gsm mat will require next to no resin. I'd mix up 30 grams of resin with 10 of hardener, and have heaps left over. Mixing less requires a more accurate scale than I've got.

(I used 280 g or resin, with 4 pieces of 200 gsm, 500 x 350, for the rack top)

With CF, you lay the dry mat on a cardboard or plastic sheet, & dab the resin onto it with a paint brush. That way, you won't lose too much of the edge fibres out of the weave. Once it's soaked, pick it up, and apply to the wetted surface to be strengthened. Lay the next piece at 45º, etc.

4 layers will end up at about ½ - 1mm thickness. You probably only need 2 layers, depending on how much stress that section is under.
 

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for such a small crack i cant see why q bond would not be sufficient i use it on fairings etc its good stuff
 

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Discussion Starter · #8 ·
Would something like this suit the job Errol, or is buying the kit overkill? Dont mind having some in stock in case I ever need it again ;)
 

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That'd do the trick. You just need a fine scale (1g increments) to allow accurate mixing.
You can expect to pay $50/m² for 200 gsm CF, and $200/5kg for the resin, so that kit is not such a bad deal.
(The filler they mention, is probably just talc)

What's q bond, feret?
 
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