This is a tapered spiral with a twist, not a straight taper. The flute radius varies down the taper (not done with a pattern router bit).
Hand coded and run on a M400 Centroid control using the macro language. Relatively short program with the cutter path calculated on the fly, less than 50 lines of Gcode. Blank was held in the 4th axis, sharp vee tip wheel cutter cutting on the side of the blank (as opposed to on the top).