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Frank
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For the last front fender, I did not fill the mounting area (picture 3, first page) with chopped carbon fibre thickened resin as usual, but rather with dry carbon fabric. Just as the rest of the mold in the vacuum injection process. With a decent result. The mounting area was completely infused with resin during the infusion and is now just as stable as the rest of the component.
Picture will follow...
Regards
Frank
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Lester Populaire
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+xThe fourth demoulded component is in order but can be improved. 1. Fault inside  2. Wall thickness in corner  3. Air bubble in the assembly area  4. Pinholes  5. Visibility of the mounting layer  6. Mold release edge clearly visible  It is very difficult for me, to drape the visible layer without wrinkles in the corner. Perhaps a 45 degree cut can give the reinforcement a better drapability? regards Frank Looks very good i would say. I think cutting the fabric at 45° would make things worse as it is going ot move around more but you still need to get in the corners just right. I assume you are using a spray tack to hold the fabrics in place? I think it is just a learning process. start in the center and work your way out. make some dabbers to push the fabric into tight corners. Once the fabric is tightly pressed against the mould the pinholes will drastically improve as well. If it doesn't work out i would cut the fabric along the tight radius and then have another patch overlapping by 10mm or so. as there will be a highlight on the tight radius in most circumstances this is hardly visible. cheers, Lester
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Frank
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The fourth demoulded component is in order but can be improved. 1. Fault inside 2. Wall thickness in corner 3. Air bubble in the assembly area 4. Pinholes 5. Visibility of the mounting layer 6. Mold release edge clearly visible It is very difficult for me, to drape the visible layer without wrinkles in the corner. Perhaps a 45 degree cut can give the reinforcement a better drapability? regards Frank
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Frank
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So, finally I produced a nearly error-free Part.  Just some tiny pinholes, which are now filled with grinding-dust.  I hope they will dissapear by polishing them with the black NW1. Frank
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Frank
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+xMy opinions: -You really should have made the mounting section separately. This would have been one of the easiest projects you can think of. -to get the cloth in wrinkle free (assuming one fibre direction is along the length of the part) start with the middle line, and then work your way outward in parallel lines, in soft strokes starting form the centre in both directions. You can either use 0° or 90° as your starting line. You used spray adhesive during the bagging? To seal the bag? That's what the gum tape is for. to protect the bag from edges and screwheads most people use breather cloth. Ec has a video about an airbox, where they bag a 3 part mould. That's basically how it should be done. @oekmont The mounting section is not my biggest problem in the moment. And: the mounting section is already part of the mold. I fill it with a mixture of chopped carbon fibre strands and resin. That works well so far. I also have no problems with wrinkles because I can make the visible layer with some side-cuts and overlay in a not visible section of the part. So I don't have to cut my weave in 45° degree angle (what would end in a lot of waste). I did not use the spray to seal the bag. I sealed the cutted edges of the bag with the gum tape. After the bag was still leaking I tried to fix the problem with pray on the outside of the bag. To use breather cloth for the protection of the bag is a very good idea. Thank you for that. I know the airbox-video from ec. They use prepreg in it. During the next days i am going to clean the mould and make another try with protected edges and screwheads and perhaps a well sealed bag. I will post it here... Frank
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oekmont
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My opinions:
-You really should have made the mounting section separately. This would have been one of the easiest projects you can think of.
-to get the cloth in wrinkle free (assuming one fibre direction is along the length of the part) start with the middle line, and then work your way outward in parallel lines, in soft strokes starting form the centre in both directions. You can either use 0° or 90° as your starting line.
You used spray adhesive during the bagging? To seal the bag? That's what the gum tape is for. to protect the bag from edges and screwheads most people use breather cloth. Ec has a video about an airbox, where they bag a 3 part mould. That's basically how it should be done.
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Frank
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The vacuum leakage drives me crazy...  I bagged the whole Mould. It took me over 4 hours and the bagging was still not properly sealed. I gum-taped all nuts and bolts, every edge, I used 1/2 can spray adhesive all around the bag and i tried a second bag over the first. Nothing helped. At the end I started the Infusion and the Part failed again. Is there somewhere a bagging workshop? Am i that stupid? Frank
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Frank
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After i failed with the first part, i would like to start a second try with resin infusion. Here are some Pictures of the Mould: The mould is about 85 x 25 cm. Picture 1 side view  It ist a four-part mould. The 4th part is a Polyurethane cast. Picture 2 inside  Everything necessary for Mounting is inside the cast. Picture 3 the PU-cast  I could fill the holes with a mixture of chopped carbon fibre strands and resin and let it cure. After this has cured, i could lay the layers of carbon and the additional layers to get the desired thickness, than the peel ply, perforated Release Film, infusion mesh and then the bag outside of the whole Mould. Is that a way that may succeed? Where should i infuse and where to connect the Vacuum? Another Thing: It is basically a U-profile with a kink inwards. If I interpret this with 2/2 twill fabric, wrinkles appear on the sidewalls, which I do not get draped away. regards Frank
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Hanaldo
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Well, perhaps. But I would suggest switching to a more advanced process, like resin infusion or pre-preg. Or at the very least, wet-lay vacuum bagging. You really need some sort of consolidation to hold things in place while the resin cures. Wet-lay vacuum bagging may be slightly cheaper, but it does also require a good amount of skill to get a good result. Resin infusion and pre-preg are much more forgiving, but more expensive processes.
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Frank
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+xStandard behaviour for wet resin in contact with a mould surface that has been treated with a chemical release agent. The chemical release agents lower the surface energy of the mould so much that the resin can't 'cling' to it, and so the resin tries to form a shape that has minimal surface contact: a sphere. You mean another try without EasyLease and Meguiars wax instead of it would help? Frank
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