I have used router on my lathe. As the router is mooved along the lathe the lathe is turning and a spiral is obtained. A grade wheel fastened to the end of the pedestal is used to get correct distance between the different spirals. In this case 60 degrees between each spiral. To be able to obtain a pedestal that is empty inside, the pedestal wood is built up of six pieces 15 mm tick and 90 mm wide glued together and turned circular. Four of the middle pieces are made empty in the central part before glueing. The result is a pedestal cosisting of six spirals covering round top and bottum plates.