|Produced to help you get the best possible
performance from your new Magnetic Drilling Machine, this guide contains
simple, sensible pointers for the safe, effective and long term use of
Please read this carefully before
using a magnetic drill unit.
If you are unfamiliar with the use of
annular (or broaching) cutters, take a few minutes to read this guide -
you will benefit from the better performance and longer life of the tool
if you understand the concept.
Check that all the relevant components
and accessories for the machine are included and undamaged, the list of
contents is included on the machine instruction leaflet.
Assemble the unit according to the instructions,
and make any necessary adjustments.
Ensure that you have observed all the
general and specific safety procedures.
Annular cutters only cut material at
the periphery of the hole, rather than converting the entire hole to shavings.
As a result the energy required to make the hole is lower than for a traditional
The broaching capacity of a machine
is therefore greater than the twist drill capacity. The slug ejected after
the cut also has a higher scrap value than shavings
BEFORE you start to drill. . .
The ease with which material can be drilled
is dependent 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
The cutting conditions can be dependent
upon requirements for tool life and surface finish and further restricted
by the rigidity of the tool and work piece, lubrication and machine power
The harder the material the lower the
cutting speed. Some materials of low hardness contain abrasive constituents
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.
It is preferable to set and maintain a
constant surface speed (RPM) for a given material and vary the feed rate
within defined limits.
Machine feed is measured in inches or
millimetres per minute and is the product of RPM x number of teeth in the
cutter x feed per tooth. Too light or excessively high feed rates will
both cause premature cutter failure. Heavy feeds on hard materials will
cause chipping of the cutting edge and excessive heat generation.
Slender and long shanked cutters are restricted
in feed rate due to deflection, and wherever possible the largest and most
robust tool must be used. This is important for harder materials. Steel
up to 400 HB is the potential limit for conventional M2 HSS tools. Above
300 HB, cobalt alloy cutters should be considered for increased tool life.
In softer grades of material, cobalt alloy cutters may give increased output
by increasing speeds and feed rates by up to 50%. Tungsten Carbide cutters
permit surface speeds and feed rates up to twice those for standard cutters.
Ensure the power is off before working on the
Insertion of pilot pin
The pilot pin is used to both center the cutter
and to eject the slug on completion of the cut. It has a flat side to allow
the coolant to run down to reach the centre of the cut where the heat is
greatest. Slide the pin through the hole in the centre of the cutter shank.
Fitting the cutter
The cutter is attached to the arbor
by way of two grub screws that grip on the flats of the shank on the cutter.
Line up the flats on the shank with the grub screws on the arbor and slide
the cutter into the arbor. The screws must be tightened evenly to ensure
that the cutter does not move. The Allen key used is one of the set included
with the machine.
Mark the position of the hole (not
Position the Machine
Make sure the workpiece is clean and flat
and position the machine with the pilot over the centre of the hole to
be cut. Fit the safety chain.
Switch on the power and energise the magnet.
Recheck the pilot is still centred
on the hole position - energising the magnet can sometimes cause the unit
to move slightly from the centre mark, reposition if necessary.
The magnet will hold on all ferrous materials
from a minimum of 6mm (1/4") inch thickness.
Starting the cut
Cutting oil ensures longer cutter life
and enables the slug to be ejected cleanly. A 500 ml bottle is included
with every machine.
Apply a reasonable quantity of cutting
oil to the surface to be cut. • On machines with an internal oil arbor,
fill the reservoir in the arbor through the small holes at the top.
On machines with a coolant system, oil
will be automatically delivered to the cutter when the cut commences
When cutting on vertical surfaces or upside
down, cutting paste, gel or foam is recommended. It is best applied inside
the cutter before drilling.
ALWAYS lower the safety guard, start the
motor and then wind the cutter gently down to the surface of the work and
apply light pressure until the cutter has made the initial groove in the
surface. Increase the pressure until the motor is loaded.
Maintain steady pressure throughout the
rest of the cut. Too much pressure will not speed the cut, it will reduce
the life of the cutter and may cause damage to the motor. If the shavings
become blue add more oil.
If the power is interrupted during the
cut, the magnet must be reset before the motor will restart.
At the end of the cut the slug will be
expelled. Withdraw the cutter from the work piece, stop the motor and switch
off the magnet.