hood problem

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hood problem

hood problem

hood problem

Author	Message
beliblisk	b beliblisk posted 5 Years Ago HOT Topic Details
b Group: Forum Members Posts: 53, Visits: 2.8K	Hi guys. I ran into a bit of a problem today. So i made e46 m3 hood. All good except for a little bulge (located in middle kevlar/cf "island on the right side o)n the top side (that i didnt notice untill todat when i took glued item from top mould) :/ After mild postcure (sun so max 50*C atm) it came out great so somwhere from that point to prior of bonding halves together this happend (inbetween i was only cutting vent holes). Stack was as followed (top part) : -245 2x2 cf -600 2x2 cf -200 cf/kevlar All this time (apart from cutting & triming) paet was laying flat in mould to awoid any accidental damage in workshop. Halves arenow bonded and i can not seperate them again. I was thinking of heating it gently locally with heat gun and then put so soft weight on and let it cool of (as atm TG is quite low...... plan was to let it full post cure bolted on the car and then sand it and get it clear coated). Any ideas how this happened and any alternative ways to solve it? Thanks a lot Edited 5 Years Ago by beliblisk
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oekmont	oekmont posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 550, Visits: 27K	90°? what is the point of that?
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Steve Broad	Steve Broad posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x oekmont - 6/10/2020 10:39:18 AM 90°? what is the point of that? Placing the overlaps at 90 degrees so what little reinforcement they gave was spread in both directions. Seemed like a good idea at the time. Lining them up on top of each other may have been better but I am not making another one to find out :-)
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hood problem

beliblisk - 5 Years Ago

It's possible that putting the part in direct sunlight and letting it get to that sort of temperature quickly might have caused the blistering. Unless made with pre-preg at an initial elevated...

MarkMK - 5 Years Ago

Oh no! I'm sorry that is no fun. Can you tap on it and get a sense of how thick the delaminated part is? If it is the top skin you may be able to re-inject it with resin and re-bond. I have done this...

explorecomposites - 5 Years Ago

Hi guys. Its a bulge not a blister. So just a little "sinked" area about 10cm in diameter and 1mm deep. Other than cosmetic imperfection is good so no delamination or bad surface finish (well apart....

beliblisk - 5 Years Ago

Oh that's better I guess - delam in single skin parts is unnerving. At least you could fill it in with clear and block it out. Interested to know if the heat and re-shape works. I have had some...

explorecomposites - 5 Years Ago

Hi. Thanks. It to a lot of time getting moulds ready:) Yeah plan B is to fill it with clear coat and sand it out. Pic of the whole hood is prior to bonding inner half (inner half is altered a bi...

beliblisk - 5 Years Ago

Is there any chance there was a little bit of debris in the mould when you put it back into the mould? I've seen that happen before. Even a tiny piece of resin from the infusion mesh can cause dents....

Hanaldo - 5 Years Ago

Hi. I do always remove particles from the mould (just to avoid any unnecessary scratches) but that doesnt mean i got them all. This sounds possible and ill be extra careful from now on. Any idea how...

beliblisk - 5 Years Ago

Unfortunately I don't think anything is really going to fix it so it isn't visible again. Even filling it with clear and blocking it flat again, that will look good in the reflection, but the carbon....

Hanaldo - 5 Years Ago

Yeah it wont be perfect in any case. Ill post update in the next week or so. Thanks for support:)

beliblisk - 5 Years Ago

Sometimes you just have to say 'Uck It!' and start again if you have to have a perfect finish. The time spent trying to fix a defect so that it is invisible can be longer than the time taken to make ...

Steve Broad - 5 Years Ago

Easy Steve, you'll upset people talking like that 🤣 Completely agree about doing it again if perfection is the goal though. Repairing carbon is doable, but it just won't be the same, it will always...

Hanaldo - 5 Years Ago

Agreed its just the cost of the stack in the hood that makes it worth trying to fix it. This was a prototype piece so some hickups were expected (but i expected inner half would suffer some cosmetica...

beliblisk - 5 Years Ago

Didn't realise that it was a prototype. Also, as you are making them for customers and they want the carbon look you can't paint them :-)

Steve Broad - 5 Years Ago

Well prototype (not like ill change mould features) in terms of layup, cut lines for louvers and fittment. Still if i can sell it to cover material cost (plus moulds) that would be great:) ATM its.....

beliblisk - 5 Years Ago

6kg!! That's heavy for a bonnet, especially for track use. This whole rear clam weighs 4kg untrimmed. A BMW bonnet for a race car I would expect closer to 2kg.

Hanaldo - 5 Years Ago

Look at those guns:D Well its just local drift/TA/track days so not really that high level so i wanted to create something with all OEM features and not flimsy that bends each time you give it odd.....

beliblisk - 5 Years Ago

I will see your 2kg and lower it to 1.5kg, after a little bit of trimming :-) https://www.youtube.com/watch?v=qpL19DHCB58

Steve Broad - 5 Years Ago

Haha c'mon Steve, either you're a giant or that's a much smaller panel! :laugh:

Hanaldo - 5 Years Ago

Every gram counts guys. LOL. Still, 6kg is a massive saving over the OEM steel version. But you could certainly loose more if you wanted it really light.

Warren (Staff) - 5 Years Ago

Absolutely! An old race car builder back in the day told that that once you had removed the easy weight, in order to remove the next lb (told you it was a while back :-) ) you have to remove an ounce...

Steve Broad - 5 Years Ago

Well OEM alu sits at 10.4kg. Top half weights 2.5kg and its 1mm thick. This bonnet is quite big as i just managed to get 1.5m cf cloth to fit:) OEM closing mechanisms will be used and with these.....

beliblisk - 5 Years Ago

Agreed, there are considerations other than simply weight that have to be taken into account. My Elan door weighs 2.6kg including polycarbonate window, hinges, locks and handles. However, I added a.....

Steve Broad - 5 Years Ago

Nah, weight is king, screw the rest 😉 Haha to be fair, I was mostly just jibing. Bonnets can be difficult to get a lot of weight out of, they are big flat panels. The rear clam I posted a photo of...

Hanaldo - 5 Years Ago

I experimented, making two small curved panels using one and two layers of 200gsm prepreg. I would have loved to have used one layer but this was just too flimsy and see though! I disagree with your...

Steve Broad - 5 Years Ago

90°? what is the point of that?

oekmont - 5 Years Ago

Placing the overlaps at 90 degrees so what little reinforcement they gave was spread in both directions. Seemed like a good idea at the time. Lining them up on top of each other may have been better....

Steve Broad - 5 Years Ago

You are talking about regular twill, or am I wrong? 0° or 90° should not be a significant difference.

oekmont - 5 Years Ago

It was nothing to do with the twill. it was the number of layers at the joints. Where the strips overlapped there was an extra layer. If I overlaid the two layers at the same place there would be 4.....

Steve Broad - 5 Years Ago

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