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Hi forum, I have this project where I need a ball or sphere between 2 corrugated stainless steel tubes, made from a lightweight and heat-resistant material and my best idea was to use carbon and glass fiber with Easy Composites "Very High Temperature Epoxy Laminating Resin". The current stage of the project is where I have cast the first real test with the following: 1 3D printed mold between the tubing, made from PVA which is water soluble and easy to remove after casting 1 inner layer of carbon fiber braided sleeve 2 middle layers of fiber glass braided sleeve 1 outer layer of carbon fiber braided sleeve My 2 issues are air gaps in the braided sleeves, and that the resin does not fill these gaps. This first test was made in steps. First the inner carbon fiber layer was put in place on the mold, then the first glass fiber layer was fitted, and then I wet it out with the resin. I wrapped it with some household food wrapping, which I removed before the resin became solid. The weekend after, I put on the next 2 layers of sleeve dry, and wet with resin, this time I used more resin, so as to be sure there was enough for filling all gaps. With resin still dripping of the part, I tightly wrapped it in some white PE foil, which was easier to use that household wrapping, as it was more tough. This wrapping I also removed after 6 hours of curing, which made it easy to remove, no sanding needed, the resin was still not solid, but it was thick enough to hold all the fibers nicely in place while removing the foil. I used heavy duty polyester sewing thread to hold the braided sleeves in place, and to force it down into the grooves in the tubing. So, my questions are: 1. How do I make sure the braided sleeve is a tight fit with no gaps between the braids? Do I need a different sleeve? Did I get a lightweight sleeve where I should have found a heavier sleeve with tighter braids? The carbon fiber sleeve I used is this: https://composite-point-shop.de/faserverstaerkungen/kohlefaser/schlaeuche/591/kohlefaser-flechtschlauch-10-58mmThe glass fiber sleeve I used was this: http://shop1.r-g.de/en/art/2011052. How do I make sure the resin fills any gaps in the sleeve so I will get an airtight casting when finished? Maybe the fiber wetting was not complete when I wrapped the foil around, pushing excess resin away from the outer layer, leaving some of the inner layer still dry, and during the first hours of curing, when the resin is still liquid, the resin found it's way to the dry spots, leaving gaps where the fiber sleeves had gaps? Just to clarify, vacuum infusion is not an option for me, this project does not justify the cost of the extra tools and materials. But maybe a different approach to the way I laminate would help. I have attached a few pictures of the process here, I don't know how to make them appear as images, sorry.
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Maybe use a heat shrink tape or tube rather than trying to wrap in clingfilm or foil. This will apply more pressure to the system and can usually be cut off easily after the cure. The diameter delta is quite large so it may be better to make it from tow rather than fabric. You could rig the thing up to a power drill on a really really slow speed to rotate it. You could then flood the tow with resin and control the amount and direction of the fibres around the sphere whilst keeping tension on the tow.
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