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1 7.3
GRINDING OF WOOD DRILLS
Grinding wheel: depending of the material the drill is made of, thin corundum or thin
diamond wheel.
Adjustment of the drill in the prism:
•
Main cutting edge parallel to both graduation lines
•
Project the drill: approx. 35 - 40 mm outside the prism
Adjustment on the machine:
•
Tip angle: 1 80° left
•
Clearance angle: to your requirement
Grinding of the drill:
By carefully feeding the prism towards the wheel and meantime swivelling the prism,
grind the first side cutting edge, then move with the motor feed to the centre tip of the drill
bit and grind over the tip using the
45°
dressed side of the grinding wheel.
Note the No. on the scale of the prism feed and move back, remove the prism of the
prism support, reverse, fix again in the support and grind the second cutting edge to the
same graduation No. Now the second side of the tip is ground centrically. Move with the
motor feed to the left and grind the outer cutter with the dressed side of the grinding
wheel.
The second outer cutter grind with the same setting.
The tip thinning is identical as for twist drills (see page 1 8).
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