ISO 4026
ISO 4026 - Hexagon socket set screws with flat point
Hexagon socket set screws with a flat point, the ISO standard that replaced DIN 913: the same headless screw as the cone point ISO 4027 and DIN 914, but the thread ends in a flat face that presses on the shaft instead of biting into it. The screw is threaded over its whole length and driven by a hexagon key in the socket of its other end, so it sinks fully into its hole and nothing stands proud. A flat point holds by friction and leaves the shaft unmarked, which makes it the point for parts that are often reset, for shafts with a ground flat, and for adjusting and stop screws. The flat face dp is about 0,7 d and is reached by a 45 degree chamfer from the thread; on short screws, up to a length that depends on the size, the chamfer at the socket end is 120 degrees instead of 90 and the socket is shallower. Steel screws are made to hardness class 45H and stainless steel ones to classes A1-12H, A2-21H, A3-21H, A4-21H and A5-21H; the thread is ISO metric coarse with tolerance 6g and the product grade is A. Covers threads M1,6 to M24 with lengths from 2 to 60 mm.