Uxcell 1/4-28 Unf Round Die, Machine Thread Right Hand Threading Die,, 2Pcs Round Die: Thread size: 1/4-28 UNF; outside diameter (OD): 20mm / 0.8"; Thickness: 7mm / 0.28"; accuracy class: 6g. Made of alloy tool steel, hardness, high torque, good toughness and wear-resistance. Applications: Can process, correct or clean the external threads. Suitable for general purpose threading in stainless steel, aluminum alloy, cast iron, copper, iron, aluminum, plastic, etc.. Great for maintenance and repair work on pipes, boards and machinery. Features: Conical locking hole, strong locking and not loose. Perfect for re-threading existing threads in hard materials like metal and making new threads in soft material such as plastic. The surface is lubricated with grease to prevent rust, the thread is clear and easy to repair. Easy to Use: The positioning groove of the die should be aligned with the fastening screw in the middle of the die wrench, and the screw should be inserted into the slot of the die and tightened. The end of the bar should be chamfered 1*45 degree, and the chamfer is too large to cut in. Tips: It needs to be reversed every 1/4~1/2 turn to facilitate the chip discharge from the chip hole. Suitable lubricating oil should be added to the cutting edge of the die when tapping the thread. The bar diameter should be smaller ( about 0.05mm-0.15mm) than the nominal diameter of the required thread. Excessive diameter can easily cause difficult cutting and lead to damage to the die teeth.