HSS Tap (Thread Cutting)

If the thread can be cut where the hole was drilled, the workpiece is never clamped twice. In steel fabrication and site erection that is one of the biggest time savings available: the machine is already holding the hole axis, the tap enters on that same axis, and the thread cannot run out of square with the hole. The BDS HSS tap range is defined in thirteen metric sizes from M8 to M42 — M8, M10, M12, M16, M18, M20, M22, M24, M27, M30, M33, M36 and M42. The material is high speed steel. The tap does not mount in the machine directly but in the safety-clutch tap holder, and that distinction matters: the clutch cuts torque when the tap bottoms out or the flutes pack with swarf, which is what keeps it from snapping off inside the hole. Extracting a broken tap usually puts the component itself at risk, and the clutch holder is the answer to that risk. Pilot hole diameter governs the size choice — every metric size has its own tapping drill diameter, and in a hole drilled to anything else the tap either fails to form a full thread or is forced until it breaks. Tapping speed is lower than drilling speed; where the machine has speed steps, drop it before fitting the tap.