this is the third part that comes out exactly the same and i've done 3 diff things so far.... my kitchen oven minum is 76c so i leave that 2 hours and then take it to 110c this time i added peelply on the edges but nothing... the stack is as fallowed  2 layers of pre-preg aviation no face side... ... eassycomposite unperforated release film and breather all over the mold put inside a bag and full vac... any ideas guys... this is dirving me crazy already 

left one is the previous one.. wich i started sanding to try and recover the part... 

Looks like bridging from the pictures. You haven't got the cloth into the recesses in the mould. Because pre-preg is quite resin light there isn't enough resin to fill the voids. With infusion the voids would have filled with resin, still not ideal but you wouldn't have those dry spots. You really need to force the cloth into any recesses/tight corners to ensure it is in full contact with the mould surface. With pre-preg being sticky it won,t move in the mould even when you pull vac.

Warren

Carbon Copies Ltd

Yep looks like bridging on the corners and the pin holes are going to be a problem until you can find a way to cook the material correctly.. What material are you using?? I saw your other post and you were using a normal oven... You need a lot more control than that will give.... Sorry.. 

I have made the exact same part and have had no problems once I sorted a lay up which stopped the risk of bridging..


I am using pre-preg too and you can get very good results if you can cook the material in a proper controlled manner..

i put breather EVERYWHERE....

more power.... want to sell me those plans for the cardboard box oven please :-)

Ok... Cool.. I know Nick from 666 and I know who made some of his moulds... long story and quite dull or not depending on who's side you hear....lol.. I had use of his hugger mould (made by the guy who made some of the 666 moulds) and it was full of stress cracks... I dont think they looked after the moulds too well at times..lol.

The pre-preg my be one of the problems as it sounds like it is an autoclave only pre-preg. The only off the shelf out of autoclave pre-preg that works is either VTF261 from Cytec in Derbyshire (50 meter minimum order now apparently) or Easypreg from Easy Composites (it is the same stuff.....). I know it works but I also have to say people have had some issues with pin holes with it too as it is not a guaranteed pinhole free finish even though you can get those results.

I use a material from another supplier which works very well but is not one they sell as a comparable material to VTF261, I just happen to have found a way to make it work.. It is part breather stack and part curing shedule and it took me 6 months of testing to find a way that would work each time I laid up a part.

The oven is not a secret and not hard to make up to be honest but it has to be well controlled and very little temperature difference between the top and bottom and I have at worst 1 degree difference top to bottom... it takes anything from 30 minutes to a day to set up how it works though.... If you imagine a open box with one side open. You need to make it so air is blown down one side (a narrow channel is enough) to the deepest point of the box then flow back out of the box again. Then you need to have a sliding door to close and stop all of the hot air just spilling out again. It has to let some air out but keep most of the heat in... The door slides to let me control how much air comes out.. Too much and the oven loses temperature... Not enough it also loses temperature but will over heat the fan heater... You need to keep air flowing at all times.... 
One of these will do..
http://www.ebay.co.uk/itm/3KW-10200BTU-Industrial-Workshop-Square-Fan-Space-Heater-Electric-Fire-2580-Kcal-/201006642821?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item2eccedf685
You will need a controller and relay plus a box to fit it all into.. eBay is your friend......lol. The hard part is sorting out the wiring to keep the motor going when the heating element is turned off by the controller.. You will need to remove the over heat protection from the box or find one which will let you get up to at least 90 degrees.. That heater has two one for the lowest power setting and 20 degrees I think and the second one is up to 65 degrees on medium and high power... Get an electrician to sort it out..... it is not hard but does take some thinking about... Then you have the oven.... 

You will need to work out how to get your material to cure yourself though... each pre-preg is different... 

I've made this video a few months ago, using the prepreg for Easycomposites.

thanks guy.. ive seen that video im subscribed to you... i know about the eassy preg... the problem is the client wanted this rear hugger plain weave and i havent been able to find plain weave pre-preg that will work... so i had to use this crap... the third part had acceptable pinholes i could live with apart from the bridging... morepower on the sides of the hugger did you cut the fabric to be able to layup first the sides then the middle part???  with infusion i was having problems too i was getting 3d looking c.f from the bridgin so i cut pannels out... but do this to plain weave i dont think it would look good

Yes I cut the sides and matched them in.... Plain weave is harder to find I use a plain weave but it is a lot more prone to pinholes than twill and you have to be 100% with everything you do to get it pin hole free or almost pinhole free... The layup has to be perfect, the breather stack and curing schedule has to be followed exactly every time. If the bag is not perfect it has some pinholes... I leave the pump running on the bag for the full cure and still find if there is a slight leak it is OK but you find some pinholes....