Ok, I really really need to figure this out. I have screwed up 4 roofs so far because the core is lifting the first layer of the laminate making it noticable were the core is. Check out the pics
ANY help would be greatly appreciated!
We have 1 layer of kevalar and 1 layer of 12oz biaxle glass, then the core and 2 layers of 12oz biaxle glass.
I have cut the core at a 45 degree angle and it still does the same thing! Any suggestions??
what kind of core are you using? have you beveled the edges down to zero around the perimiter of the core? are you infusing, or wetlay?
Probably you’re using wet lay up that’s why the first layer is lifting,you need to force the first layer against the mold’s surface. I tried using core with vacuum and it worked fine, no lifting. For wet lay up I would apply the first layer, let it dry a bit and then the second layer - core - and the rest of the layers, this way the first layer will stick to mold’s surface and won’t lift when adding core.
However when using cores infusion is the best way and then vaccum bagging and last wet layup.
Just my opinion
Stupid idea: place the core in a pattern where you can paint some sort of design on top, to cover the problems 
Hmm…even cutting the core down is doing this? I have has issues like this before using infusion, with both trimmed, and straight cut core edges. Maybe you need more layers on the top surface, or 2 cure cycle.
Is this at the edge of the core material or between pieces of core?
I am using infusion as my method of manufacture and it is 1/16th inch foam core. It is doing it on the edges of the core. I am not pieceing them together anymore cause they will do it between the core too if I don’t have it perfectly lined up
Is this a curved part? It seems to me that the core is basically briding across the tool surface. The middle of the core is not making contact when layed up, and then gets pushed down when bagged, which deforms the fabric in contact with the edges of the core.
I thought that too but the core I have is quite flexible. If that is the problem what do you suggest I do so it does not do it?
I don’t know TET…sounds odd. But if that IS the case, then use some spray adhesive on the layers, and core when laying up. It won’t deform then.
Long story about the pic, ignore the Parrot.
But that is 2 layers of 24oz spread tow fabric, and 3 strips of core, and another 2 layers of fabric. Same thing happened to me, but I didn’t bother trimming the edges.
I see from the first pic that the core chamfer is quite short. You said it was 1/16 foam core, correct? What is the length of the chamfer? The chamfer usually needs to be down to 0.050 +0.0/-0.05, also the top of the chamfer neeeds to be rounded .5 Radius. If this is 0.062 this core that doesnt really give any chamfer at all so this would need to be a chamfer to 0.0 and probally quite a bit longer. Is the foam you are using compatable to the resin you are using? Is it stable to the temp of cure and pressure of vacuum bag?
I see the material is all full plies at 0/90 with no doublers going up the chamfer of the core and the plies are pinching when they are getting sucked into the bottom of the chamfer. Again how tall is the bottom of the chamfer? If there was a doubler on top of the core before the full plies extending from beyond the EOP to .5 on top of the chamfer at 45 degrees, it would help the transition of load from laminate edge to cored panel.
Another idea would be to cure the skin with peelply then co-cure the core and bagside plies, but you are doing resin infusion, so probally not.
its probably from the bag slightly bridging at the core’s transition. make sure your core is beveled perfectly and press with a rubber squeegie around the core once you have medium vacuum and higher.
I doubt it, as his core is almost paper thin! By the time his 2 top plies go over it, the smooth out the transition.
Although it may not actually be bridging, it could very well be some other sort of bagging problem. If the bag is pulling inward, it may be bunching up the fabric against the edges of the core.
These problems could likely be solved by making the part better with more plies, a balanced layup, and proper ply orientation with some at ±45*. Then paint the part so it actually matches the car!
Maybe do some small flat test pieces. Different angles, ply ori., etc. Also, try debulking a few times. Which means, pull full vac, vent, pull full vac, vent, etc. Each time, work the corners of the core, and make sure everything is tight.
Also, maybe use spray adhesive on the first few layers, and core, but not the top layers. Hmm…
Any comments about my post at the bottom of the last page??
I still feel the chamfer needs to be longer and down to a 0.00 edge. The addition of the doubler would help also.
Damn I wish they would just paint them argg… Well I think I figured it out. I just took the extra time to push everything down better and it seems to be working. Here is the updated one
I also made sure the gel was very tacky when I layed the kevlar down to help it stick to the surface of the gel coat and not lift