code: def make_pilothole_cutter(self):
          
          # get pilothole ratio
          #   note: not done in .initialize_parameters() because this would cause
          #   the thread's profile to be created at initialisation (by default).
          pilothole_radius = self.pilothole_radius
          if pilothole_radius is None:
              (inner_radius, outer_radius) = self.get_radii()
              pilothole_radius = inner_radius + self.pilothole_ratio * (outer_radius - inner_radius)
  
          return cadquery.Workplane('XY') \
              .circle(pilothole_radius) \
              .extrude(self.length)
docs: Make a solid to subtract from an interfacing solid to bore a pilot-hole.