Even for a small set of hand tools for hand tapping in the holes — you need to have several a ratchet (or one — with several square holes). As shown, more convenient universal — sliding knob. Here is a pretty simple design, developed in the school № 27 of the city of Gorky. The knob consists of two parts. The housing is machined from steel rod Ø 15 mm and length 105 mm. on the one hand he protochen on the length of 65 mm to Ø 8 mm, with the other threaded hole M6. The Central part of the body is milled or processed with a file on two parallel planes to a thickness of 9 mm. in the Middle of this area is perpendicular to the axis of the drilled hole of Ø 6 mm. needle files it is given the shape of a Pentagon (see Fig.) with a 90° angle at the apex lying on the longitudinal axis. Then a segment of “silverfish” Ø 8 mm and length 89 mm made handle. Its shank length 24 mm grinds up to Ø 6 mm — for M6 thread, and in the middle part of the belt is 20 mm knurling.
