it is also used when you roll CF tubes over a mandrel commercially. Actually, they use a heat shrinking material but the idea is the same. And it does indeed squeeze out some resin – though of course it is harder to control exactly how much as opposed to vac-bagging prepreg and/or using a breather layer.
Commercial tubes need a smooth finish at low cost… but the shrink film has a price: the thickness of the laminate will be thinner at the center and thicker at the ends. Winding the wet roving is a more precise method but even if i’ve been in the composites industry for 20 years i don’t feel like going through that…. a cnc lathe may do but not me :S
A good method, if i ever decide to make them professionally without asking to your neighbors (which actually can be a good idea if you find the right molding company 😉 ), is to use an external mold with internal bladder…. that is what is done by C4 and others. I have also used sometime a funnier method with internal rigid model + bladder for very complex layups and that is really fast as you can layup the layers while waiting for the mold to be back in production… and the rigid model can then be removed quite easily… but how to do that is a little secret 😛
Prepreg is actually used to achieve a higher ratio reinforcement/matrix for particular needs but it is way too far for spearguns where the forces involved are relatively small and the weight is not an issue.
Anyway let’s wait to celebrate because there are still many things that can go wrong in this gun…. Murphy’s laws are always there!
