Threaded shank drill assembly

A combination drill and drill adapter comprising:

• a drill having a shank portion for mounting the drill, the drill shank being generally cylindrical in shape and, at a portion adjacent to an end of the drill, a plurality of substantially flat sides parallel to the longitudinal axis of the drill extending along at least a portion of the shank;
• and
• a drill adapter having a circular opening in one end with a depth greater than the length of the flat sides of said drill for receiving the drill shank end portion and a mounting member at the opposite end for mounting the adapter in a drilling device, said adapter opening having a first diameter at the portion of the opening away from the end less than the diameter of the drill shank cylindrical portion and greater than that of the diameter of a circle tangential to the sides at the end of the drill shank and a second diameter at the portion of the opening adjacent the end greater than the first diameter and slightly less than that of the the drill shank cylindrical portion,
• said drill shank end being assembled into said adapter opening such that the sides of said drill
• shank end broach walls of said adapter opening diameter away from the adapter end and the drill shank cylindrical portion fits against walls of the adapter opening at the second diameter adjacent to the adapter end without broaching to hold said drill securely in said adapter for mounting of the assembled drill and adapter in a drilling device.

A method of assembling a drill and drill adapter comprising the steps of:

• a) obtaining a drill having a shank portion for mounting the drill, the drill shank being generally cylindrical in shape and, at a portion adjacent to an end of the drill, a plurality of substantially flat sides parallel to the longitudinal axis of the drill extending along at least a portion of the shank;
• b) obtaining a drill adapter having a circular opening in one end with a depth greater than the length of the flat sides of said drill for receiving the drill shank end portion and a mounting member at the opposite end for mounting the adapter in a drilling device, said adapter opening having a first diameter at the portion of the opening away from the end less than the diameter of the drill shank cylindrical portion and greater than that of the diameter of a circle tangential to the sides at the end of the drill shank and a second diameter at the portion of the opening adjacent the end greater than the first diameter and slightly less than that of the the drill shank cylindrical portion;
• and
• c) pressing said drill shank end into said adapter opening such that the sides of said drill shank end broach walls of said adapter opening at the first diameter away from the adapter end and the drill shank cylindrical portion fits against walls of the adapter opening at the second diameter adjacent to the adapter end without broaching to hold said drill securely in said adapter for mounting of the assembled drill and adapter in a drilling device.

A threaded shank drill for high torque loading applications comprising:

• an adapter portion having a hale of a predetermined diameter and depth in a first end and a threaded shank on a second end, opposite the first end, for mounting the drill in a drilling machine, said hole having a plurality of diameters with a larger diameter near the top of the hole and a smaller diameter near the bottom of the hole;
• and
• a drill portion of hardness greater than the adapter portion having a cylindrical shape of a diameter slightly larger than said hole larger diameter with a drill tip at a first end and a plurality of sides around an opposite second end, the second end of the drill portion having corners at regions between the sides, said corners extending beyond the smaller diameter of said adapter hole,
• said drill portion second end being assembled into said adapter opening such that the corners of said drill portion second end broach walls of said adapter hole at the smaller diameter near the bottom of the hole and the cylindrical drill portion fits against walls of the adapter hole at the larger diameter at the top of the hole without broaching to hold said drill portion securely in said adapter for mounting of the assembled drill and adapter portions in a drilling device.