I'll open this to keep Steve's V8 thread focused. So far this qualifies as what i didn't make with CNC, but it is the reason for building up the Series 1 with the 4th axis.
This is a 1/3 scale 1915 "F" head Harley Davidson. Also called a pocket valve because the intake and exhaust valves oppose one another in the small manifold adjacent to the cylinder. The intake is actuated by an overhead rocker arm, while the exhaust is through a tappet direct from a follower on the cam. So far the patterns have been conventional for the crankcase and timing gear case in aluminum, and the flywheels in cast iron. The machined knife and fork rods carry dummy pistons in test samples of lost wax vacuum cast cylinders of aluminum.
The original cylinders are a single casting with .100" fins over 1" deep less than .250" between them, so in 1/3 scale this amounts to .033" and .080". Pretty tough to draw from even oil bonded sand, so I'll try lost wax with either the vacuum or centrifugal method. I tried to make silicon molds of the complete casting, but the wax pulled the silicon and destroyed the mold due to the small dimensions. The first success was the cylinders shown, which were made with a set of turned molds to form single fin wax rings which were then stacked and fused to make the cylinder assembly. While I will need to make the cylinder in 3 pieces of machined wax then fuse them together my hope is that by eliminating the wax mold and injection there will be no need for draft. The small size and complexity of the waxes is the challenge I hope CNC will solve.
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