18
THE CORRECT USE OF DRILLS
A guide to successful drilling
•
Make sure the workpiece is securely held and supported.
Should it bend or move, it could cause the drill to break.
•
Use a good socket and thoroughly clean both the socket and
the taper shank of the drill. Do not use steel objects to seat
the drill.
•
Straight shank drill chucks must be able to hold the drill
securely.
•
Keep the drill sharp. Do not allow it to become blunt as it will
require extra-grinding to get it sharp again.
•
Direct an adequate supply of the recommended coolant to
the point of the drill. (see page 11).
•
Do not allow chips to clog the drill flutes.
•
When re-sharpening take care to achieve the correct point
geometry (see page 22/24) and do not overheat the drill
when grinding.
•
Use core drills for enlarging existing holes - 2 flute drills
are not designed for this purpose.
•
Use the correct drill to suit the application (see page 6-9).
Deep Hole Drilling
A general guide
A hole deeper than 3 times its diameter is considered a “deep hole”.
Deep holes are successfully drilled by reducing speed and feed rates,
as shown in the table on page 11. Care must be taken not to clog
the flutes with chips. In very deep holes it may be necessary to
withdraw the drill frequently to clear the flutes. Extra length drills
should be used with a guide bush as close to the workpiece as
possible to support the drill.
