Can this work?

General Composites Discussions Composites Talk
#1

I’m in the process of building a bonnet (hood). But I’m planning to use a 3 mm core material (soric) for this. I want to sandwich the soric between carbon (outside visible layer) and woven glass (inside layer). But instead of trimming the bonnet afterwards to the right size and shape, I’m planning to lift the correct size and shape bonnet out of the mold after infusion.
Reasons for this, I’m concerned that the white core material will be visible after trimming.
And with only garage hand tools I’m afraid i won’t be able to make a clean straight cut.

So I’m brainstorming with this idea. I heard about rolling edges, but i don’t understand the moulding process so here is my lay-up idea, will this work?

  1. Cut the first layer of carbon over size and bond it with infusion mold glue to the mold.
  2. Then cut the core material to the EXACT same size as the plug and glue that down
  3. Cut fiberglass to the exact same size as plug.
  4. Then fold over the excess carbon of step one over the other two, so theoretically speaking it should be the same size as the plug, lying from edge to edge in the mold.

Here is my (5 year old) drawing of my process,

is this how it should be done, or is there a hole in my plan…?

#2

its possible, might find using a caul plate across your flange to your part could help you achieve a net shape part. Just a warning though, soric eats lots of resin. You could also end the core slighlty short.

#3

yeah im kinda limited to soric. its the only core material imported to South Africa.

#4

1: sure, don’t see why that won’t work. might be hard to keep things even and perfect as you fold it over, but careful work will make you happy.
2: Make the core smaller. No need to have the core ALL the way to the edge. Make 3-5cm smaller than the part, and you will only trim the composite fabric.
3: make it all out of carbon, no glass…so much lighter, and as mentioned in another post, the thermal mismatch between the glass and the carbon might delaminate from the core.

#5

Soric will print through to the surface unless you take steps to prevent it.

#6

what is the right way to mold a bonnet? cut off the excess materials? these bonnets are purely for cosmetic purposes. so i make them for that purpose.