16
Do not grind away too much cemented carbide
Do not grind too much on the top of the
buttons. Let a few millimetres of the wear flat
remain on top of the button.
Always grind broken buttons flat
A drill bit can remain in service as
long as the gauge buttons maintain
the diameter of the bit. Fractured
buttons must always be ground flat
to prevent chips of cemented carbide
from damaging the other buttons.
Avoid grinding the perimeter
Gauge-button anti-taper has to be removed by grinding, although
excessive reduction of the bit diameter should be avoided. Leave
about 2 mm of the wear flat. If necessary, remove some of the bit-
body steel below the gauge buttons, so that a clearance (taper) of
0,5 mm is maintained. If the flushing holes start to deform, open
them up with the aid of a rotary burr or steel file.
2 mm
Min
0,5
Grinding equipment
Grind Matic BQ3-DTH
For “permanent” grinding stations, a
mechanized stationary grinding machine
is available, the Grind Matic BQ3-DTH. It is
equipped with automatic feeding devices
and grinds both the cemented-carbide
buttons and the bit-body steel in one
operation. The machine uses diamond-
impregnated grinding wheels.
Grind Matic Manual B-DTH
The grinding machine Grind
Matic B-DTH is a mechanized
air-powered grinding machine for
button bits. It is mounted in a steel
box-barrow, which can be wheeled
easily around the work site. The
Grind Matic Manual B-DTH uses
diamond-impregnated grinding
wheels.
Safety: Service
• Take great care when breaking the driver chuck joint using
the bit removal tool in combination with reverse rotation.
If the shaft of the tool is not locked or touching the edge
of the feed beam, the shaft can turn with great force when
breaking the driver chuck joint.
• Blows against hammer or bit can cause fragments of metal
to fly. Always wear goggles when breaking joints.
• Never disassemble the spring unit if the friction springs
may be preloaded.
• Before grinding, always check the flushing holes of the drill
bit for traces of explosive. Contact with the grinding wheel
can cause the explosive to explode causing serious or fatal
injury as well as damage to the equipment.
• To clean the flushing hole, use only a wooden rod, copper
wire or fiushing water.
DANGER
• Take great care when handling the drill bit. Mind your fingers!
• When removing and fitting exhaust tubes, always wear
protective goggles, gloves and appropriate protective clothing.
Carelessness can result in injury to the eyes or other body parts.
• Foot valves are brittle. Heavy blows can deform or disloca-
te the exhaust tube, with the risk that it would then obstruct
the movement of the impact piston.
WARNING
• Always wear ear protectors, protective clothing, gloves and
goggles when grinding.
• Use a dust extraction system or an approved dust mask.
This is of special importance when dry grinding indoors.
CAUTION
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