carbon fiber drop outs

[LoHiFab]

How do you make them? I understand the bit about fabricating a beefy mold that requires a lot of pressure (and temperature) but I'm lost as how you do the layup to get just the right amount of material in the mold, and in just the right way.

[crumpton]

How do you make them? I understand the bit about fabricating a beefy mold that requires a lot of pressure (and temperature) but I'm lost as how you do the layup to get just the right amount of material in the mold, and in just the right way.

What you describe with "beefy mold" and "lot of pressure" is compression molding. In the classical sense the molds are designed to capture the material and retain 100% that which is placed into the cavity. It can be a tad be complex in tool design for a multi dimensional part(something beyond a block). The volume of the mold cavity is calculated/known as is the mass of the material being molded. volume to mass is calculated and that mass of material is placed into the mold. Off to the press for pressure and cure. The material used is not like normal UD or weave but rather comprised of a set of width and length random strips in a lower tac resin. Also call Bulk Molding Compound(BMC). You may have seen it in some finished parts, looks a bit like OSB.

All the carbon dropouts I've done to date are actually water jetted from engineered plate that I've either made in house or had other sources make. Multi-profile faces have been done by bonding the various water jetted shapes of individual thicknesses to accomplish the profile. Like this one where there is a recess for the hanger.

[LoHiFab]

great answer, thanks.