The first step to Carbon Fibre

[davsato]

Originally Posted by Kymmy

Actually an autoclave is just the heat bit and not the vacumn. You tend to vacumn and then cure with heat afterwards. Few autoclaves have built in vacumns but they are specialist at curing resins that need the the vacumn, the pressure though is equal within the autoclave and has no bearing on mold pressure.

well actually it does big time. at the beginning of the cycle at room temp the vacuum is on the inside of the bag to keep the work still and held against the mould. the autoclave is basically a big pressure cooker, so as temperature increases pressure inside the vessel does too and eventually the pressure pushing on the outside of the bag is greater than the vacuum inside, so at this point the vac line is vented to atmosphere and it continues on pressure alone. during the cycle temp and pressure can reach 220c and 7bar.
this depends on what youre going to put in it of course, an autoclave works on pre-impregnated cloth and would be wasted on lick and stick wet lay ups. if youre using an ordinary epoxy or polyester resin then you would help it with a little warmth but its keeping the humidity down thats more important, resins are hygroscopic and absorb moisture from the air. too warm would make the resin too runny and it would vac out leaving the work dry, too hot and you risk an exotherm which you dont want. your airing cupboard would be ideal.
100psi doesnt sound a lot but the autoclave we got at work is big enough for hercules radomes, you can stand up in it and if it burst bits of us would be found some miles away.

you can get good results with a simple vac bag on carbon but always use a bag, the fibres are stiff and wont lay on to eachother very well if they are not held down and you could end up with an air filled resin rich thing that is weaker and weighs more than the original.

[scarfacehugo]

OK!!!

Weekend 2 of the CF experience...

Decided to use 2 layers of carbon, 1 fibreglass and the last one kevlar/carbon just as a test.

The pictures describ it, including the final result but improvements must be done. I'm still not sure if this part can be "salvaged"...

The "Henry" process works better than I expected, but it needs a bit more practice and experimenting , but afterall this is the "bodger's corner"...
Let's not forget we're talking about trial/error procedures, without any kind of training. Absolute discovery.

If anyone can point out what I've done wrong so that air bubbles show in the part, please share it with us. Thank you!

[davsato]

Originally Posted by scarfacehugo

OK!!!

If anyone can point out what I've done wrong so that air bubbles show in the part, please share it with us. Thank you!

too much resin not enough vacuum.
that milky build up with the bubbles in is excess resin where the cloth isnt going into the sharp corners properly.
thats why an autoclave runs at 80-100psi, but henry maybe at 10psi?
looks like your there pretty much though, but there are a few things you could do.
you can gently roll some resin out of the job starting at the middle working out, dont try too hard or it will probably make the weave "wavy" and fray the edges.
when you put the breather mat over it put some rings of mat around those bumbs where the resin builds up, this will help the bag press in harder into the sharp corners.
scrunch the bag up into the mould hollow before you put the vacuum on, to make sure you have plenty of bag to expand into every knook and cranny. dont worry about putting wrinkles in the job.

looks an excellent first attempt though mate, thats not an easy shaped piece youve decided to copy, well done

[Jenna]

as davsato says the resin has pooled between the mold and CF, its a big problem your going to have without a decent vacuum. You can get round it to some extent by using thinner CF fabric and loading the wadding up to put more pressure on it were the mold is curved. For something like that panel I would suggest 7-8 layers of the lightest CF you can get (not sure if you also know, the type of weave effects greatly how much the fabric will drape!)

You may also want to filler that honda logo out... they will see it as its not bad enough you have copied their design but to rip off their trade mark too will get you an invite to court!!

[scarfacehugo]

Thank you for your directions.

I didn't use the peel ply , because I read some where that it's mainly to leave a rough finish, in case you want to bond anything else on top of it...
but, I did use release film with the little holes and breather fabric as you can see. What I think might have happened, is the resin hardening too fast , not leaving enough time for the breather fabric to absorb the excess. I did put the whole thing on top of the central heating radiator right after vacuuming it...

The part itself, I guess I can still save it by sanding the excess resin until it reaches the first cloth layer...

Anyway, good fun , although the result wasn't the expected, I'll keep on it.

Cheers!

[scarfacehugo]

Originally Posted by Jenna

You may also want to filler that honda logo out... they will see it as its not bad enough you have copied their design but to rip off their trade mark too will get you an invite to court!!

Yes, I am using 200g plain weave carbon cloth, as it seems to me it's the easiest to mold to tight corners, but cheers for that.

Thank's for the tip, Jenna...but I'll leave the "rules and regulations" obsession for the natives.

Cheers

[Sohoeasy]

You may also want to filler that honda logo out... they will see it as its not bad enough you have copied their design but to rip off their trade mark too will get you an invite to court!![/QUOTE]

She's right you know, They can get real funny about it. Seems like a "trickle" of a problem but untapped trickles become torrents. So unless your Chinese blank it out.

( You could get your chissel out and make a little Scarface mould to sit in there ?

[foz1969]

Brilliant.. keep @ it!! practice makes perfect & all that. THE BIG QUESTION.... how much are your side panels, fairings etc goin' to be? Good work!

[scarfacehugo]

Originally Posted by foz1969

Brilliant.. keep @ it!! practice makes perfect & all that. THE BIG QUESTION.... how much are your side panels, fairings etc goin' to be? Good work!

Mate, so far, this lovely piece of c... as cost me £250 and many hours of labour. For somenthing as big as a side panel, it should cost me about 2 grand, plus labour and profit, £3000 should do it. I TAKE PAYPAL!!!