I tried unsuccessfully to lay up a head tube on a turned polished aluminum mandrel. Even with 3 layers of high temp release wax, post cure the carbon would NOT come off the mandrel. Back to the drawing board. Next I conducted a test using UHMW as a mandrel. It has a higher coefficient of thermal expansion than aluminum and nothing sticks to it (at least not epoxy). It turns up in the lathe nice and smooth and the 250F cure temp has no lasting effect on it.