Slotted screw screwdriver with decreasing blade thickness - has concave work surfaces contacting side edges at under 90 degrees

摘要

Screw driver for slotted screws has a shaft with a blade with two counter sided working surfaces, the blade ending in a face surface. The thickness (b) of the blade (2), going from the flat surface (8) over a part (a) of its extension in the direction of the shaft (4), decreases. The work surfaces (6) come together with the side surfaces at the edges at an angle of less than 90 degrees, and in the lengthways direction of the blade (2) are curved in a concave fashion. The blade enters the shaft at a constant rate of cross-sectional alteration, and the side surfaces can also be curved in a concave manner.