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5 Working with operation tools
5.1 Twist drills
DRILLING CONDITIONS
The ease with which material can be drilled depends on several factors including tensile strength and
abrasion resistance. Whilst hardness and/or strength is the usual criterion, wide variations in
machinability can exist among material showing similar physical properties.
The drilling conditions are dependent on requirements for tool life and surface finish. These
conditions are further restricted by the rigidity of the tool and the work piece, lubrication and
machine power available. The harder the material, the lower the cutting speed.
Some materials of low hardness contain abrasive substances leading to rapid cutting edge wear at
high speeds. Feed rates are governed by rigidity of set-up, volume of material to be removed, surface
finish and available machine power.
DRILLING A HOLE
Now that you have read the explanatory information and safety recommendations above, you are
ready to actually start drilling. Follow these 12 steps for best drilling result :
1.
Install the twist drill according to the original instructions of the fitted hand drilling machine.
2.
Precisely mark the centre of the hole
3.
Place the magnetic drill frame in the correct position by letting the tip of the twist drill but
meet the marked center of the hole.
4.
Switch on the magnet and verify that the drill is in the right position and that the machine is
pushed tight against the work piece.
5.
Make sure the fitted hand drilling machine is switched on and (If possible) drilling speed is
set correctly following the original instructions of the fitted hand drilling machine. Switch the
fitted hand drilling machine on with the on/off switch on the magnetic drill stand and allow it
to run at the required speed.
WARNING:
Never use the hammer function of a fitted hand drilling machine!
6.
Turn the arms to start drilling. Apply only a slight pressure when the twist drill bit touches
the metal. Do not push the twist drill bit with force into the metal.
7.
Apply a regular pressure while drilling. The drilling performance does not improve by putting
more pressure on the tool. Too much pressure will overload the motor of the fitted hand
drilling machine and your twist bit will be worn sooner.
Let the twist bit do the job and give it time to cut the metal!!!
8.
Apply cooling fluid when necessary. Stop drilling regularly to do so.
9.
Apply less pressure when the drill cuts through the material.
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