Pin mirror cutter, and throw-away tip mounted on the pin mirror cutter

A pin mirror cutter comprising:

• a first tip mounting seat formed in a peripheral face of a substantially annular cutter body which rotates around an axis;
• and a second tip mounting seat formed in an end face of the cutter body,
• wherein a first throw-away tip in which cutting edges are formed at intersecting ridgeline parts between a pair of oppositely disposed long side faces of a substantially trapezoidal flat-plate-shaped tip body and upper and lower faces of the tip body are mounted on the first tip mounting seat such that a thickness direction of the tip body is approximately aligned with a radial direction of the cutter body to provide cutting edges formed in acute corner parts of the tip body for cutting,
• wherein a second throw-away tip is mounted on the second tip mounting seat such that the thickness direction of the tip body is approximately aligned with an axial direction of the cutter body to provide cutting edges formed in obtuse corner parts of the tip body for cutting, and wherein the throw-away tips are mounted on each of the first and second tip mounting seat such that one of the long side faces of each provides rake faces in a cutter rotation direction, and
• wherein an axial rake angle of the first throw-away tip is positive relative to the cutter rotation direction, and an axial rake angle of the second throw-away tip is negative relative to the cutter rotation direction.