It’s gonna be pretty:-)
Lamberto, did you use kitchen film wrap (Vita Wrap) on top of the CF sock after laying it up? Some people do that in marine and modelling applications. You can add a bit of pressure onto the cloth that way and if the film doesn’t wrinkle too much, you can even get close to a nice finish. Obviously, you would need to insert something in the track to push down on the CF there.
(Just thinking out loud for the sake of others, I know you have done these things before 😉 )
No need for surface film in this case: the carbon fibers are braided as a tube (a “sock”) so it is enough to slide the core inside and pull the two ends to get perfect adhesion to the core surface.
The contact glue is used to force the fibers in place where the core has a negative curve (spear track and handle details). In theory i should have built a sock -dispenser that is a PVC tube slightly bigger than the core and where you push the sock in nice and ordered way before sliding it on the core and release the sock straight and nice on the sticky surface…. as i didn’t have the right PVC pipe (actually i may have some in the chaos of my cellar but only God knows where…. :blush: ), I proceeded slowly to the sock job (by turning it in-out and slide it on it’s self): the wrinkles are only relative to fibers alignment in some points where i pushed too much, that means that in some point they are not nice and straight as they can be… only aesthetic issue in this case.
If you use a film on a tubular and complex shape as this one you will end with much more trouble than advantages: the rule “Better is enemy of Good” apply also to spearguns construction… 😉
In composites structures the optimal percentage of reinforcement (carbon) and matrix (epoxy) is extremely important and the film techniques (vacuum or pressure) are used to get a laminate that respond to the design specification: with a kitchen film you can, at best, get a smooth surface of the laminate and often not even that… it is a home-made attempt to replicate at home the peel-ply/breather technique used in industry… and not really successful at that.
Today the resin was over gel stage and start hardening (the cellar is quite cold luckily) so, being the resin still “open”, i have given a second layer of epoxy to build-up a thicker cover that then will be finished with sandpaper without damaging the fibers underneath and will protect it from scratches and impacts. One or two more layers of epoxy and then is ready for sanding, opening of the trigger housing and installation of hardware.
P.S. : 8 hours do not include epoxy curing-time… it would be necessary an oven and that goes into the “fancy tools” list 🙂
