I have done lots of research on composite molding over the past several weeks and it is now time to get my hands dirty. After tweaking the desired frame geometry in the CAD model, I am ready to cut a test mold for the headtube. Photo above is the finishing pass, and I am not overly concerned with surface finish quality at this point.
Below is a mold half with the CNC cut foam core, offset the desired wall thickness. The foam provides a shape to wrap the carbon during the wet layup. It will also provide better compaction of the carbon in the tighter radius portions of the mold.
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The MDF mold is a very porous material and the epoxy will adhere to it. As a shortcut mold release, I lined the mold with packing tape, since the epoxy wont stick to it. The foam core is also wrapped in plastic sheeting and tape to aid in the remove post layup. In order to get better compaction in the mold, a latex bladder is typically used. Another shortcut here, I have used an inner tube to provide compaction. I will inflate to ~40psi once the mold is closed.
As this was just a test, I only used three layers of 6oz unidirectional carbon fiber sourced from Soller Composites. The resin system used is Adtech 820 with the 822 hardener. After 24 hours in the mold, results are show below, on the right with after trimming and flash removal.
Surface finish is quite good with the exception of wrinkles from the tape mold lining, which was expected.
The next step is to fabricate another mold, this time with inserts to control the ID for headset installation and top/down tube junctions.
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