Instruction example 12.5. Drill with standard drill point as well as flat drill point and centre point
Exercising of sharpening of drills in the most used types of
drill point grinding
Material
worn-out drills
diameter: 4 to 12 mm
Figure
Working Tools
Measuring and testing tools
Grinding gage or protractor
Accessories
Coolant (water)
Required previous knowledge
Reading of the drawings, measuring, testing, drilling
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Sequence of operations |
Comments |
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1. Arrange workplace prepare working material |
- Check for completeness |
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2. Lay the drill with the standard drill point (1) between thumb
and forefinger (left hand) and advance the drill with the right hand towards the
grinding wheel so that the main cutting edge lies horizontally and the drill
itself exactly horizontally. The setting angle is about 56° from the
left-hand side |
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3. Press the drill slightly against the wheel and push it
towards above and at the same time slightly to the right-hand side -at the top
take it off |
- Grind both cutting edges uniformly (alternately) - and cool!
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4. Check for grinding faults as well as for adherence to the
angles given |
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5. Take the drill with the flat drill point and centre point (2)
as described above and press it with the main cutting edge exactly vertically
against the horizontally lying grinding wheel, in doing so, the centre point
must project at the right-hand grinding wheel edge! |
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6. Push the drill with a slight pressure in vertical direction
towards above, at the top take it off |
- Cool!
Grind uniformly at both sides! |
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7. The centre point is sharpened by lateral grinding at the
right-hand grinding wheel edge |
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8. Checking for grinding faults |
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