		Driling, Countersinking and Counterboring - Course: Technique for manual working of materials. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 18 p.)
			(introduction...)
			1. Purpose of drilling
			2. Machines for drilling
			3. Tools for metal drilling
			4. The operation of drilling
			5. Setting of the tools
			6. Clamping of the tools
			7. Clamping of the workpieces
			8. Technological process of drilling
			9. Purpose and application of counterboring/countersinking
			10. Labour safety recommendations

Workpieces roust be clamped in such a way that they cannot fling around or be drawn up.

Small workpieces can be held by clamp dogs or hand vices on a support if only a small rotary power is to be expected (small bore holes).

Figure 13 - Holding of flat, small workpieces in the hand vice

Larger workpieces are safely clamped in the machine vice that can be equipped with straight or prismatic jaws.

Cylindrical parts may also be clamped in the drilling v-block

Figure 14 - Clamping of small workpieces in the machine vice

Very big parts must be clamped on the machine table directly.

For this purpose, clamps and locking screws as well as other auxiliary means are required.

For series and mass production, drill jigs are used.

Figure 15 - Clamping of big workpieces on the machine table by clamps

1 - Clamps
2 - Step block
3 - Locking screw
4 - Supporting hexagon (fixed at the clamp)
5 - Workpiece
6 - Machine table