Method of forming a die for roll forming a dual threaded bolt

A method for forming a die usable in roll forming a dual threaded bolt, the die having a substantially flat forming surface between a pair of opposing side edges and a pair of opposing lead and rear edges, and with a plurality of substantially parallel coarse thread crests extending from the lead edge to the rear edge and angled relative to the side edges, and a plurality of bridges located within roots that are between the crests, the bridges angled relative to the crests and extending between respective adjacent ones of the crests, the method including steps of:

• cutting the forming surface with a truncated coarse thread cutter having a circular form with cutting teeth on a perimeter thereof, the cutting teeth having a tip and a notch in the tip with tapering slopes matching a contour of upper portions of the coarse thread crests, said cutting step using the tip of the truncated coarse thread cutter to form the upper portions of the substantially parallel coarse thread crests and with the notch of the truncated coarse thread cutter forming the upper portions of the coarse thread crests, the tapering slopes of the notch of the truncated coarse thread cutter forming the tapered sides of the coarse thread crests;
• and
• further cutting the forming surface with a fine thread cutter having a circular form with cutting teeth on a perimeter thereof, the fine thread cutting teeth having a tip between angled surfaces, the tip of the fine thread cutter narrower than the tip of the coarse thread cutter, said further cutting step using the fine thread cutter between the upper portions of the plurality of substantially parallel coarse thread crests to form the roots between the coarse thread crests, the roots including the bridges therein within the roots and between the crests and the bridges angled relative to the crests, the tip and the angled surfaces of the fine thread cutter forming the roots and the bridges within the roots.