cone spinning
as as we did while spinning the first small test cone, we extended the mini lathe with some aluminum profiles. this enabled us to use the lathe from the "back side", therefore a larger diameter of material could be turned."
here is our first video:
other than at national resophonic mandrels, the shape of our wooden (mdf) mandrel is negative.
side view of the mdf sandwich and the mounting to the lathe
as raw-material we used a 0.2mm thick aluminum sheet, and cut out a disc
the aluminum disc is fixed on the outer diameter of the mandrel and than pushed slowely inside using a wooden stick and some oil (next pic).
the mandrel is spinning at a slow rpm. depending on the handling of the wooden stick (-slower move of the stick -> smoother surface), we got an astonishingly smooth surface!!
to spin the cone on the outside we make a small hole in the middle and srew it on the mandrel, so it is easier to get a flat surface on the rim of the cone
when we take out the cone of the mandrel it looks like this. we finish the cone by cutting the rim with a scissor
by using a block of hard wood the cutted rim is pusched gently inward.
three cones ready to use
first test fit into the guitars soundwell
the cone fits pretty well into the soundwell hole, a "quick and dirty" made bridge allows us to hear the first ever sound from this beast!!! - just great!!!