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		Grinding of Simple Tools - Course: Technique for manual working of materials. Instruction examples for practical vocational training (Institut für Berufliche Entwicklung, 23 p.)
			(introduction...)
			Introduction
			Instruction example 12.1. Centre punch and scribing punch
			Instruction example 12.2. Steel scriber
			Instruction example 12.3. Screw driver
			Instruction example 12.4. Flat chisel and cape chisel
			Instruction example 12.5. Drill with standard drill point as well as flat drill point and centre point

Instruction example 12.1. Centre punch and scribing punch

Exercising of sharpening of punches

Figure

Material

- Worn punches or
- Round material of silver steel:

(carbon content 1.1. to 1.25 %)

Diameter:

10 mm

Length:

122 mm

Working Tools

Hand hacksaw

Measuring and testing tools

Vernier caliper, grinding gage or protractor

Accessories

Coolant (water)

Required previous knowledge

Reading of the drawings, measuring, testing, scribing, prick-punching, (sawing - when producing the punches)

Sequence of operations

Comments

1. Arrange workplace prepare working material

- Check for completeness

2. Sawing of the round material to length

- only if a original tool is not available!

3. Face grinding of one face

- Press workpiece in vertical direction against the wheel, turn it slowly around its axis

4. Grinding of a 4 mm chamver on this face - horizontal or vertical position

- Press workpiece against the wheel with a setting angle of 45°, in doing so, turn is speedily and uniformly around its axis

5. Grinding of a 50 mm long taper, proceeding from the other face-horizontal position

- The right hand guides the workpiece, the left forefinger lies between the workpiece and the grinding support - press workpiece in horizontal direction against the wheel, turn is speedily as well as push it forward and back

6. Grinding of the point - vertical position!
(1) - Centre punch 60°
(2) - Scribing punch 40°

- Press against the wheel only slightly with quick turning of it around its axis -risk of drawing the temper!

7. Final check

- Angle, accuracy to sice grinding pattern (as per drawing)

Completion:

Have the point hardened to HRC 50

Centre punch and scribing punch

Sequence of operations	Comments

1. Arrange workplace prepare working material	- Check for completeness

2. Sawing of the round material to length	- only if a original tool is not available!
3. Face grinding of one face	- Press workpiece in vertical direction against the wheel, turn it slowly around its axis

4. Grinding of a 4 mm chamver on this face - horizontal or vertical position	- Press workpiece against the wheel with a setting angle of 45°, in doing so, turn is speedily and uniformly around its axis

5. Grinding of a 50 mm long taper, proceeding from the other face-horizontal position	- The right hand guides the workpiece, the left forefinger lies between the workpiece and the grinding support - press workpiece in horizontal direction against the wheel, turn is speedily as well as push it forward and back

6. Grinding of the point - vertical position! (1) - Centre punch 60° (2) - Scribing punch 40°	- Press against the wheel only slightly with quick turning of it around its axis -risk of drawing the temper!

7. Final check	- Angle, accuracy to sice grinding pattern (as per drawing)