Cutter holder with reduced assembly tolerances

A cutter holder comprising:

• a holder having
• a front end having an end surface;
• a rear end;
• an outer surface;
• a conical recess recessed in the end surface of the front end of the holder;
• a first threaded portion formed around the outer surface of the holder, located at the front end of the holder, and having
• an external thread defined as an external trapezoidal thread and having a major diameter and a root diameter;
• a first abutting surface being adjacent to the external thread away from the end surface of the front end of the holder and having a diameter larger than the major diameter of the external thread;
• a second abutting surface being adjacent to the external thread near the front end of the holder and having a diameter smaller than the root diameter of the external thread;
• at least one recess recessed in the second abutting surface;
• and
• at least one sealing member mounted in the at least one recess and partially protruding from the second abutting surface;
• a collet mounted in the conical recess of the holder;
• and
• a nut screwed with the holder and having
• a second threaded portion formed around an inner surface of the nut, engaged with the first threaded portion of the holder by threaded connection, and having
• an internal thread defined as an internal trapezoidal thread corresponding to the external thread of the holder in position and thread shape;
• a third abutting surface being adjacent to the internal thread, corresponding to the first abutting surface of the holder in position, and having a clearance formed between the third abutting surface of the nut and the first abutting surface of the holder being less than 0.015 millimeter;
• and
• a fourth abutting surface being adjacent to the internal thread and corresponding to the at least one sealing member in position, wherein the fourth abutting surface of the nut and the at least one sealing member of the holder are in an interference fit.