Hi guys, i have been working on a carbon fiber project for about 4 months now and am still having issues with getting consistent moldings. I struggle most with air bubbles due to the fabric pulling out of tight corners. Here is a link to a video that should give you a good idea of what I am having trouble with. Please let me know any suggestions you might have. Thanks!
https://youtu.be/uYhvCo5sblc (Please ignore vertical video syndrome)
using polyester resin and 3K plain weave fabric
Carbon fiber is not very good at conforming to tiny corners and cuts like on your part but there are some things you can try…
Twill weave confirms to curves better than plain. 4x4 twill drapes better than 2x2 but is more expensive and heavier. Don’t use plain weave for this type of thing ever.
If you try and cure all of the layers at the same time it will make it even harder to conform to tight corners. It’s like folding paper a bunch of times - it gets harder and harder to fold… Try curing the surface layer on it’s own and then adding additional layers afterwards once you have it right.
Add resin to the cf on a flat surface and let it get tacky before you try sticking it to the mold
Use epoxy not polyester, at least for the surface layer so you can get some decent adhesion. Polyester resin sucks for what you are trying to do. Epoxy may be more expensive but wasting all your cf costs even more.
Add weights on top of the rigid bladder you are using to press it down properly for the whole cure and / or make a heavier bladder out of fgs plaster.
Try losing the parting wax and just using pva mold release. Parting wax causes me a problem every time when there is tight corners and it stinks too. If the part seems stuck, use hot water to melt the pva away. Wax will stop parts conforming to curves.
If you are using heat cure resin, don’t. Use room temp resin. Heat cure resin briefly turns back to liquid when curing and without a vacuum, the cf will come away from the mold corners. If you were just using regular room temp resin, why are you putting it in the oven? Room temp resin is destroyed by high heat (like 250 degree) usually and this is probably the reason for the yellowing too. The only other cause would be exposure to UV light. It won’t be caused by excess resin unless you are using that cheap nasty fiberglass resin from home depot. If the resin isn’t curing fast enough for you, leaving it in a warm room will speed it up a little and you can add more hardener but definitely don’t use the oven.
Hope this helps