Spiral flute tap

A spiral fluted cutting tap for cutting threads into a wall of a bore, the tap comprising:

• an elongate body having a forward end and a rearward end;
• the elongate body having a fluted portion beginning near and extending in a rearward direction from the forward end, and the fluted portion having a spiral flute defining a cutting edge adapted to cut threads;
• the spiral flute presenting a concave cutting face, and the concave cutting face being defined by a first radius;
• the spiral flute further presenting a concave core surface adjacent to the concave cutting face, and concave core surface being defined by a second radius;
• the spiral flute further presenting a convex blending surface adjacent the concave core surface, and the convex blending surface being defined by a third radius;
• the spiral flute presenting a convex heel surface adjacent to the convex blending surface, and the convex heel surface being defined by a fourth radius;
• and
• the spiral fluted cutting tap having a core diameter, and the core diameter remaining substantially constant along the length of the fluted portion.