import cadquery as cq
w0=cq.Workplane('XY',origin=(0,0,-50))
r=w0.sketch().circle(50).reset().face(w0.sketch().segment((-27,36),(-25,19)).arc((-31,-3),(-21,-24)).segment((-19,-41)).segment((27,-36)).segment((25,-19)).arc((31,3),(21,24)).segment((19,41)).close().assemble(),mode='s').finalize().extrude(100)