2Pcs Straight Flute Tap High Speed Steel Metric Hand Flute Tap Standard Screw Tapping Tool M20x1.5 Item Type: Straight Flute Tap Material: High Speed Steel System: Metric Thread Quantity: 4 Thread Tolerance Grade: 0.014 Through Hole/Blind Hole: Through Hole Tap Style: Straight Slot Thread Codes: Fine Thread Application: Suitable for Thick Steel, Rubber, Aluminum, Copper, and Wood Usage: A set of products consists of 2 pieces, which can also be divided into first tap and second tap. Function of First Tap: There is a section of taper at the front of the tap, which is smooth without screw thread (very shallow), so as to facilitate the alignment between the tap and the tapping hole and ensure the perpendicularity of the tap and the hole for smooth tapping. Function of Second Tap: In addition to machining the allowance of the first tap to meet the standard, it also plays the role of polishing the screw thread (deburring). For the screw thread with blind hole, it can be tapped to the bottom. Simply, it can be said that the first tap is for rough machining and the second tap is for fine machining. The workpiece to be machined shall be clamped correctly. Generally, the side of the workpiece that needs to be tapped shall be placed in a horizontal or vertical position. In this way, when tapping, it is easier to judge and maintain the direction of the tap perpendicular to the workpiece thread base. When starting tapping, place the tap as far as possible, then press the axis direction of the tap with one hand and gently rotate the handle with the other hand. When the tap rotates for 1 - 2 turns, observe whether the tap is perpendicular to the thread base face of the workpiece from the front or side. If necessary, use a right angle ruler to correct it. Generally, the direction of the tap is basically determined after tapping 3 - 4 turns of threads. If the tapping is not correct, screw out the tap, correct it with two taps, and then tap the thread with a first tap. When all the cutting parts of the tap are inserted into the workpiece, it is no longer necessary to apply axial force, and it can be screwed in naturally by the thread.