CF bonnet spoiler - mould finish :) & damaged :(

Post by **4thgenphil** » Sun Jul 22, 2012 10:18 pm

so all the crap you gave me about using glass fibre as the mould

shame as that mold looked ace

A1ex · Post by **A1ex** » Sun Jul 22, 2012 10:30 pm

I stand by that, the fibre glass moulds I've made havent been anywhere near as good as the ones I've made with this stuff.

All I'm planning is to patch the back the strengthen it and stop the crack from getting worse

then need to smooth out the crack so it doesn't show on the parts that come out

mercutio · Post by **mercutio** » Sun Jul 22, 2012 10:32 pm

maybe you should put a layer of glass fibre over the back of the mould to strengthen it

vti2003 · Post by **vti2003** » Mon Jul 23, 2012 7:19 pm

Difficult one this.

Without seeing it in person the two options I would be looking at are :

1) Stop drill the cracks at each end if they dont go to the edges. Patch repair on the back couple of plies thick. Cure that off. Grind the crack out into a v shape right through the original plies but not into the plies on the back and fill with resin. One repair ply over the top to let you sand profile back in. Sand flush once cured.

2) More complicated but stronger : Stop drill cracks. 2 x repair plies on the back. Cure off. Step sand the original plies back. If you haven't done this before then what you are doing is replacing the original plies with repair plies but not proud of the surface except for 1 sanding ply. Pic below describes it better. You need to sand each original ply back then "stepout" as in diagram. Sounds impossible but it isn't

The sacrificial sanding ply enables you to restore the contour without weakening the repair.

Crap diagram, hastily drawn!!

The repair plies should fit into the steps exactly.

Vac bag with LOW vac on the shape you have there. Something like 5-8 inhg I would think.

Once cured resand profile. It will be stronger than the original.

If you haven't stepsanded before then try and learn on your scrap bits. That's the key to cash as you can do completely flush, high strength repairs on anything then.

Hope that helps you out

A1ex · Post by **A1ex** » Mon Jul 23, 2012 7:44 pm

^^^ epic! Just what I was looking for mate. Only thing is the mould isn't layered it, it's tooling gel (epoxy based, good gloss & rigid) and glass reinforced putty which is pretty strong & rigid too (obviously not strong enough mind). Think it's cracked where the were some bleed points I'd missed when taking it back from the edge of the part.

I guess the above process could still be used for this setup as the putty gives a good surface to key with...

BTW, can you be my mentor please

vti2003 · Post by **vti2003** » Mon Jul 23, 2012 7:51 pm

Ooops!

Ok step 1 is your answer then. Try and patch the back and open the crack up a bit to fill it

BTW, can you be my mentor please

When you have been doing this for 20 years you are gonna know a damn sight more than me the speed you are teaching yourself!

A1ex · Post by **A1ex** » Mon Jul 23, 2012 7:59 pm

Cool, I'll give option 1 a bash tomorrow then

vti2003 wrote:When you have been doing this for 20 years you are gonna know a damn sight more than me the speed you are teaching yourself!

... but until then

vti2003 · Post by **vti2003** » Mon Jul 23, 2012 8:37 pm

Happy to help a fellow luder if I can!!