Abstract: An apparatus for piercing a hole in a tube centered on a tube axis has a plurality of housing parts one which is formed with a throughgoing threaded passage centered on a passage axis and both of which are secured the housing parts around the tube with the passage axis extending generally radially of the tube axis. A tool body threadable into the passage is formed with a blind bore generally centered on the passage axis, open radially inward of the tube axis toward the tube, and having an end wall directed radially inward of the tube axis toward the tube. A straight hard metal needle in the bore has a pointed inner end directed radially inward of the tube axis at the tube and an opposite outer end confronting the end wall of the bore. The outer needle end is centered by appropriate formations in the bore on the passage axis and the outer needle end is braced radially outward of the tube axis against the bore end wall.