Epoxy-carbon composites typically have densities similar to dense hardwoods or even higher. There are some specialty low-mass composites, but those are pretty exotic- usually, wood is lighter for a given part size. Not as strong, though, which is why CF composites are useful in bikes and airplanes.
CF composites also tend to be more "ringy" than wood. Something worth exploring is loading the resin with hollow microspheres, which can help damp things and drop the density significantly. If you can run the process reasonably hot, something like a 3-4% addition of Expancel into the resin during impregnation could prove useful. Then during layup and cure, raise the heat to the expansion temp of the spheres and the composite will puff up like Jiffy Pop. Well, maybe not that much, but you can easily get a 40-50% expansion.
CF composites also tend to be more "ringy" than wood. Something worth exploring is loading the resin with hollow microspheres, which can help damp things and drop the density significantly. If you can run the process reasonably hot, something like a 3-4% addition of Expancel into the resin during impregnation could prove useful. Then during layup and cure, raise the heat to the expansion temp of the spheres and the composite will puff up like Jiffy Pop. Well, maybe not that much, but you can easily get a 40-50% expansion.
the prepeg i use has already been half cured..
so no it is not 100% safe, but i only use a small vent by convection on my oven and it is more than sufficient..
but for using prepegs for boxes, one would require a pretty big oven that could be controlled pretty accuratly
( our cure cycle as some ramps and is 130C for 1.5hour...
the epoxy goes back to semi-liquid and then starts curing when it hits 120c+ , then you need some time to let it solidify when bringing the temp down )
MDF is what, 3-4KPSI ? CF is roughly 300KPSI in TS
and half that in Comp S
so not much is required if you use some aluminum or balsa core to get a few times more stiff than 3/4 MDF
thing is that, because it will be seriously lightweight
you want to consider using something like 1"thick core,
as the weight incresase will be marginal, but stiffness will be multiplied VS .5 or .75" thick ..
probably 1-2 layers of CF inside and out would be more than sufficient ..
corners will need more attention and different use of CF
also the contour of the driver's hole would require attention to detail, as CF composites surface is very fragile because it is only the resin that is holding up,
so it is not very hard ( 6-8K PSI for the epoxy i believe)
so no it is not 100% safe, but i only use a small vent by convection on my oven and it is more than sufficient..
but for using prepegs for boxes, one would require a pretty big oven that could be controlled pretty accuratly
( our cure cycle as some ramps and is 130C for 1.5hour...
the epoxy goes back to semi-liquid and then starts curing when it hits 120c+ , then you need some time to let it solidify when bringing the temp down )
MDF is what, 3-4KPSI ? CF is roughly 300KPSI in TS
and half that in Comp S
so not much is required if you use some aluminum or balsa core to get a few times more stiff than 3/4 MDF
thing is that, because it will be seriously lightweight
you want to consider using something like 1"thick core,
as the weight incresase will be marginal, but stiffness will be multiplied VS .5 or .75" thick ..
probably 1-2 layers of CF inside and out would be more than sufficient ..
corners will need more attention and different use of CF
also the contour of the driver's hole would require attention to detail, as CF composites surface is very fragile because it is only the resin that is holding up,
so it is not very hard ( 6-8K PSI for the epoxy i believe)
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