Just be aware that using 2 layers of reinforcement does not necessarily prevent the core printing through. The best way to prevent print through is to ensure the resin is fully cured (so if it's colder than 25 degrees, cure for longer than 24 hours) and ideally post cure as well. Unfortunately bulker mats like Soric and 3D pet core do tend to end up printing through a bit. 

Thanks for the quick reply,




It makes sense with the sandwich core, I just wanted to make sure.




I'll have a look for that thread and see if it's any help.

As you say with extra reinforcement, I would probably wet-lay if needed.




Cheers,

David

I agree with ChrisR... Diolene is a better option for the bottom layer, from a cost/benefit perspective.  (and cutting/trimming the edges.)

I did not have problems with print through of the core material in my mudguards, but doing a fully cured infusion, and then adding a core + cover layer will get around that problem for sure.

The first batch of my 18" mudgards were made with no gelcoat, as they were meant to be painted and clearcoated anyway, they were infused directly, i one go, 3 layers of CF + core strips..

I cut/chamfered  the edge of the soric with a scalpel-blade at a shallow angle for the front mudguard, but not for the rear which has a sharper radius on the edge. At the time I did not notice any print through on any of the mudguards.

The next set will be made with EC Pro-finish and a "V-pattern" down the middle, and translucent green clearcoat ... I think I will infuse without the core and then add it afterwards, just to make sure not to get print-through. 

"Sapere Aude"... Dare to KNOW!

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103% of all people do not understand statistics...

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The strips of Soric were put in like a normal sandwich core, under the bottom layer, remember they were used in mudguards with no core in other parts.

I do not think they will be needed at all in a fullu Soric or Cork cored layup.  I would use peel-ply on the bottom, that will make it very easy to add some extra strips of CF tape  along the edges, if more stiffness is needed.

Also extra reinforcement can be easily added in high stress areas..

There is a thread on this forum where someone is making wings/mudguards for an Caterham/Lotus 7 but I could not locate it  in a hurry..  may be wort a closer look?

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Thanks again for the advice, it's very. very helpful.




I will probably take inspiration from your idea of using strips (how wide?) around the edge to add rigidity, would you suggest putting the core material between layers or exposed/ covered by clear coat/ under-seal?

With regards to mounting, I'm not entirely sure at the moment, but may look at using the adhesives you can buy and attach to the body/chassis a well as probably a light mounting bar.




Cheers,

David

I tend to agree with ChrisR on the number of reinforcement layers, especially for the wings, you probably will not need more than a single layer on the "bottom"

Regarding reinforcements, you will definitely need to replace the Soric or cork core with solid CF/glass in the places where you attach the "wings"  and maybe make an extra layer of CF/Twaron/Glass that extends a bit from the attachment point.

I have made long "old style" motorcycle mudguards, using just three layers of CF, but to stop them flexing along the length, I added a narrow strip of soric along the edges just inside the edge curve. It is invisible from the outside, but stiffens the mudguard so it feels completely rigid.  (Hope this makes sense .. )

I think that the pinholing issue with cork, may well be due to the fact that I used cheap floor "noise insulation" cork, and did not prepare it for infusion. I also did not use infusion mesh all over my test piece, only the ends.
(like you would with Soric)

I think that if I had done what Warren suggested to punch a grid of holes in the cork, and maybe score the surface in some way, the pinholing may have been a lot less.

The specialized cork for composite use is still cheaper than the Soric, and probably performs better then my cheap floor stuff.

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Thanks for the response guys,




Dravis -

Thanks for the advice, I was thinking of using the resin infusion technique.

I thought of using 3D-Core purely because of the curves of the wings I wasn't sure if the other cores would form as well; but if you think the 2mm cores will work then I may possibly go for the cork core, and fill the pinholes with resin before clear coating. The cork feels more in keeping with a 'special'!

The car bonnet tutorial was my inspiration for the idea.

Where would you think would need strengthening on the mudguard?




ChrisR -

The reason I looked at using 2 layers either side of the core was because of print through, though maybe I can just use the single layer of Aramid underneath as it won't really be visible.

I don't mind if it's a bit heavy I can't afford to spend a lot at the moment so would rather make a robust version to start with, and when future funds allow, look at seeing if lighter versions are feasible.




Cheers,

David

Looks a little heavy (to me) but it depends on how light you want to take it and how bothered you are about surface finish/print through from the core. 

Hi,

That sounds like a very good setup, but for the mud-guards alone, I would not spend money on 3D-Core, I would recommend 2 mm Soric.

My new infusion test shows quite clearly that 2mm Soric gives less pinholing/better saturation on the top layer, and less noticeable print-through on the bottom, than 3 mm 3D-core.

I'm convinced that a 3 mm Soric will be better and cheaper, but also a little bit heavier than 3D-core.

I also tested cheap 2 mm floor-damping cork, which works very well, but does give more pinholing/less saturation of the top layer (The one facing the mould)

I have decided to make some panels using wet-lay with vacuum bagging and the cheap cork floor mat as core.

For parts like these, I would recommend spraying (Get the Gel-coat Cup-gun!) GC50 into the mould, then infusing on top of that.

Reinforce the mud-guards with extra thicknesses of CF/Twaron in strategic places. 

(Basically do it like the "Car-bonnet tutorial")

The curved surfaces/shape of the mudguards will make the finished product very stiff and strong.

Good Luck!!

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)