Routers, like many other
power tools, are dangerous if mishandled. Please read
all of the safety instructions that came with your
Think of the care you take
when handling a sharp knife, then multiply that many
times - a router is a very sharp knife, with the blade
spinning very fast!
Wear ear protection, even
if routing for a short time - the high-pitched resonance
of a router will leave a ringing in your ears for hours
afterwards if you don't.
If you're not sure if you
should be trying a particular operation - DON'T.
Routing takes confidence, which comes from practice and
working up your skills gradually. Try again when you're
Routers are very versatile tools, but they have a
serious bite if you get it wrong!
General Care and Safety
take extreme caution when removing the protective wax from a new
cutter. Do not pull it off, as the sharp cutting edges could
cause injury. Carefully slit the wax with a sharp knife along
the internal angle of the flute and prise the coating away.
Before using a new cutter, wipe off any protective oil to
prevent it transferring and marking the surface of the work.
pull the cutter from the router by the cutting edges without
protecting your hands. If your fingers slide along the cutting
edges, you will find out just how sharp they are, then you'll
delay progress whilst you receive first aid - and you could also
bloodstain your wood!
Whatever the size of the router
bit shank, it is held into the tool with a collet assembly. This
is simply a device which relies on tightening a nut against a
taper to grip the cutter shank equally around its circumference.
The router shaft (or arbor) is hollowed and threaded at the
"business" end. The collet fits into this hollow, acting against
an internal flange, or taper, once the nut is tightened. Some
routers require that the arbor is held by a spanner whilst the
nut is tightened:
Two spanners required
Others have a press-button spindle lock fitted,
which holds the arbor, thus requiring only one spanner to be
One spanner required
|Older-style collets had a separate steel
ring inserted in the collet nut. More advanced collet
assemblies have a ring machined within the nut that
engages the collet, automatically releasing it from the
end of the spindle as the nut is undone. These are
typically made of high quality, polished tempered steel
and have multiple slits, ensuring both security and
concentricity for the cutter. They also feature slits
starting from alternate edges of the collet to provide
even pressure over the full surface area of the cutter
A double-lock system is
incorporated by some manufacturers. When the nut is undone, it
will first loosen and then appear to re-tighten, requiring
loosening a second time. This design prevents the cutter shank
being released if the collet nut accidentally loosens while the
router is running. The latest design collet systems have their
collet and collet nut factory assembled and should not be
insert as much of the shank as possible into the
collet and at least three quarters of the shank length
as a minimum, to decrease the chances of deflection of
cutter when under load. This in turn will prevent
damage to the collet, reduce wear and stress on the
router bearings and avoid the possibility of shank
damage. However, don't allow the end of the cutter to
be in contact with the internal end of
the armature recess.
maintain a gap (see diagram) of 1/16"
(1.5mm). This will prevent the possibility of any
"hammer action" being induced which could cause the
cutter to creep out of the collet (the collet nut is
represented by a rectangle, for clarity).
|Never clamp a
short portion of the shank in the collet to gain extra
|Never use collet
reducers (shown in blue here) as a means of extending
the length of the shank!
ensure that you have a minimum gap of 5/32"
(4mm) between the collet and the cutter (shown
here in red).
Make sure that the collet is kept
perfectly clean and corrosion-free. Resin can work its way up
the slits of the collet and build up around the cutter shank and
the inside collet faces. Resin build-up may cause uneven contact
between the internal collet face and cutter shank. This could
create a resonance, causing the shank to slip and leading to
collet burn, deposits being evident on the shank as brown marks.
Resin build-up can be removed by using an appropriate solvent
and a fine wire brush.
Surface corrosion can also occur
on the inside face of the collet, which will restrict insertion
and removal of the cutter. It can also cause scoring of the
mating faces and could significantly damage the collet -
sometimes beyond repair.
Dust, corrosion or dirt will
decrease the ability of the collet to grip or release the cutter
shank. Other problems include the shank slipping, bit or collet
seizing, or excess vibration leading to shank bending or
breakage. A fine wire brush will remove such deposits, but don't
use glass-paper as this will leave scratches, which could cause
If either the collet or its nut
are faulty, it is best to change both as soon as possible. Don't
use cutters with damaged shanks, as this will lead to trouble.
To prevent cross-threading and damage to the threads of the
collet nut, the inside of the nut should be kept clean and free
of burrs. If in doubt, replace the nut at the same time as the
Keep both the inside and outside
tapered surfaces of the collet clean and free from dust, resin
and dirt. This also applies to the inside taper of the arbor and
the threads of the nut and arbor. Remove any deposits with a
wire brush and regularly protect the surfaces with light oil or
Keep It Cool
A problem can arise from metal
fatigue in the collet, due to heat being transferred from the
cutter, as repeated heating and cooling cycles may alter the
original steel tempering. Sprung steel requires a degree of
inherent elasticity in order to properly grip the cutter shank.
This is reduced over time and increased tightening of the collet
is then needed. This will eventually distort the collet,
preventing it from exerting an even grip. Therefore, collets
that need excessive tightening should be swiftly replaced.
If vibration is noticeable when
you are routing, switch off at
once and investigate.
First, check that the cutter shank is not bent, that the cutter
is not damaged or blunt and that the cutting edges are not
chipped. Vibration can result from a worn collet, which is
holding the cutter out of line to the arbor axis. This may be
due to a condition called "bell-mouthing" within the collet.
Collet marks on the shank will show that the collet is worn and
this can be checked by inserting a long cutter and tightening
the nut. Apply sideways pressure on the end of the cutter and if
there is any sign of movement, the collet must be replaced.
Replace the collet and the nut at
the same time. If there is no apparent wear in the collet or
nut, the problem may be wear on the arbor, or within the
router's main bearings, both major service tasks.
For The Day?
Always remove the cutter from
the router after use. This will avoid continual pressure
being applied to the collet and the cutter shank, which could,
in time, cause a permanent distortion. After cleaning, lightly
oil the collet before storing, particularly in humid conditions,
to avoid corrosion or surface pitting.
Correct Feeding Essential
The feed direction is the direction in which the cutter is fed
into the material or, in the case of table mounted or fixed
routers, the material into the cutter.
Following the correct feed
direction will ensure safer and easier working, and allow the
cutter to cut efficiently. The correct feed direction is always
against the rotation of the cutter. This can be
ascertained by looking at the cutter itself. Routers rotate in a
clockwise direction (when looking down from above the machine)
and this determines the direction in which the cutter rotates
and - subsequently - the feed direction.
If the feed direction is
incorrect, the forces involved in cutting will cause the cutter
to try to drag the router along the workpiece. This situation
can swiftly become unstable and dangerous, particularly if it
takes the operator by surprise.
When routing inverted in a table,
the feed direction is right to left. If the
material is inadvertently fed in the wrong direction, it could
be ripped away from the operator and - in the worst case - drag
the operator's hand into the cutter. Whilst it is possible to
take a very light "cleaning" pass in the "wrong" direction
(known as "climb cutting"),
this is an operation that should only be attempted when
the operator is fully conversant and totally
confident in handling and controlling their machine.
It is a good practice to mark the
direction of feed (right to left) on the worktable fence when
using your router inverted in a table. With portable routers,
the rotational direction of the cutter is often marked on the
machine, although with experience this will become second
Speed Is Important
Many modern routers
have variable speed, set with a thumb-wheel or slider.
Some have a recommended speed chart attached to the
router body, like this one which relates to the
markings "A" to "F" on the speed thumb-wheel and
speeds of between 10,000 and 23,000 rpm.
Routers with a single
speed will rarely be able to use large cutters, as
they will exceed the RPM recommended by the cutter
manufacturer. Separate variable speed controllers are
available for connecting between the router and the
power source. However, these are unlikely to offer
full wave rectification or speed compensation and do
not maintain the available power evenly throughout the
speed range. Inferior types of speed controller can
also affect the smooth running of a router,
particularly at lower speeds.
To minimise wear on the router
motor bearings, to prevent cutter damage and to improve the
finish of the cut face, it is important to maintain a constant
feed speed. Variations in the type of material, type and
condition of the cutter and the available router power will all
have an effect on feed speed. It is for the woodworker to judge,
by the sound of the router motor, whether the motor is
labouring. In time, you will acquire a feel for the router and a
feed speed relative to the work in hand will come naturally. You
will find that a narrow cutter can be used at a higher speed
than a wider one, although very narrow cutters will need a
slower feed speed and smaller depth of cut to prevent breakage.
Feed speed will also be affected by the type and density of the
wood, the grain direction and any variation in the texture of
the material along the cutting line.
Beware of hard knots as these can damage the cutting edges or
even chip or fracture the TCT tips. Also avoid 'dead' or loose
knots, as they can be ejected and cause injury, as well as
causing tip fracture.
If the cutter is inclined to burn the material, it is a sign
that the cutter is blunt, or that it is being fed along the cut
Working With Templates
Templates are very useful for the production of identical parts
all at one time, or the exact replication of a part at any later
date. They can be used in a couple of different ways, either
with a bit that is equipped with a guide bearing, or by using a
guide bush in the router base.
|If the bearing-guided cutter is to be used, the
template must be made to the exact size of the finished
article. Whether the bit has the follow bearing at the
bottom (as in "A") or the top of the cutter (as in
"B") - some specialist cutters have both -
dictates how the template is used with the stock
When using a bit with
a bottom-mounted guide bearing, the template must be
BELOW the stock to be routed. The bit depth is
adjusted to ensure that the bearing will contact the
template, then engaged with a sideways motion. Once
the bearing is in contact with the template, it will
follow the template shape, removing excess stock until
the shape matches that of the template.
To save stress on the
cutter, first remove as much excess material as
possible from the stock (jigsaw, bandsaw, etc.), then
there will be less material for the router bit to deal
When using a bit with
a top-mounted guide bearing, the template must be
ABOVE the stock to be routed. The bit is adjusted to
again ensure that the bearing will contact the
template, then engaged with a sideways motion. Once
the bearing is in contact with the template, it will
also follow the template shape and remove excess stock
until it matches the shape of the template.
As before, first remove as much excess material as
possible from the stock.
Working With Guide Bushes
||Using a guide bush in the
router base is another common way of following a
template, with two major differences. The first is that
there is no need to use a bearing-guided cutter - a
straight cutter is suitable for the task.
|Secondly, the size of the
template will differ from the intended finished article.
With internal templates, such as a circle-cutting design
where the guide bush follows an internal edge, the
actual template will need a hole larger
than the finished dimensions by the distance between the
outer surface of the guide bush collar and the cutting
edge of the bit (the collar-to-bit offset), as shown
||Therefore, when cutting a
template for hinge fitting, because you are cutting the
mortice using internal edges, the template has to be
larger than the hinge by the collar-to-bit offset.
|For external templates,
where the guide bush collar follows an external edge,
for example, when making a curved shape, the template
will need to be smaller than the finished
dimension by the collar-to-bit offset.
When a router follows a template,
it will reproduce everything it follows, including lumps, dips
and roughness. So one thing is clear - the more time you spend
in getting the template edge absolutely smooth and free of
imperfections, the better the finished result will be. My
preference for templates is MDF, because I find it easier to get
a smoothly-sanded finish on the edges than I do with plywood.
The router is a very versatile tool and one that is very
satisfying to handle skillfully. As with any other skill or
technique, practice is the main ingredient to success.
Above all, please BE
Safety "A to Z"
||ALWAYS use the router and other power
tools in a safe manner and away from children.
||NEVER leave the router running
unattended. Wait until the router comes to a complete
stop and switch off at the wall outlet before making
adjustments, changing the cutter or operating the
||BEWARE of unsafe working practices and
potential hazards when using a router.
||OBSTRUCTIONS should be kept clear of the
path of the router and the routing area. Do not clear
swarf or other debris away from the cutting area with
the machine still running.
||CLOTHING, such as ties or loose or baggy
garments, which may be accidentally caught and pulled
into the cutter should not be worn, or should be tied
back when using a router.
||POWER to the router must always be
switched off and the machine isolated from the supply
before changing cutters or making adjustments. Make sure
the power switch is 'Off' before plugging in, to avoid
||DUST presents a severe health risk if
inhaled. Always wear a dust protector and/or use a
vacuum extractor connected directly to the router.
||QUESTIONS regarding the safe operation of
your router should be directed to the manufacturer's
||EYE protection must also be worn to
protect the operator from ejected waste particles.
EAR protection should also be worn, especially when
routing for long periods of time.
||ROUTERS must be allowed to reach their
full running speed before commencing any routing
operation. Do not switch the router on with the cutter
touching the workpiece.
||FEED direction of the cutter into the
workpiece, or the workpiece into the cutter, should be
against the rotation of the cutter.
||SHORT-CUTS must not be taken to the
detriment of safe working practices.
||GUARDS should always be used when using a
router mounted in a table. Always ensure that your
fingers cannot make contact with the cutter. Always use
a push stick together with hold down clamps or
featherboards when machining small timber sections when
the router is mounted in a table.
||TIDY work areas and benches help to
prevent accidents. Always keep the floor around the work
area clear of all obstacles. Store router on a shelf, in
a cupboard or in a storage box, so debris cannot fall
into the air intake.
||HURRIED setting up can lead to accidents.
Take your time to prepare yourself and the machine.
Carry out safety checks before switching on.
||UNDERSTANDING the current statutory
woodworking regulations is essential for all
||INSPECT the condition of the router
cutter before use. Ensure that the cutter is held firmly
in the collet, rotates freely and is well away from the
work before the power is switched on.
||NO-VOLT release switches should be
fitted to all table-mounted routers, both to isolate the
router in an emergency and to prevent it switching back
on when power is restored after a power failure or
||JUDGE the correct feed speed by listening
carefully to the tone of the router.
||WORKPIECES must always be securely and
safely clamped to the work bench, in a vice or by some
other means prior to commencing the routing operation.
Make sure that clamps are not within the path of the
||KEEP router cutters sharp. Take care when
handling them, especially when removing them from the
collet or from a storage block.
||EXAMINE the cutters and router
collet before use. Equally check that any knobs or
screws on the router are tight and have not vibrated
||LISTENING to the sound of the router will
often indicate that the cut is being made too deep or
that the cutter is blunt.
||YOUR safety when routing is more
important than the router or its cutters.
||MANUALS and other information supplied
with the router or cutters should be read thoroughly to
ensure you are familiar with the controls, functions and
||ZERO accidents should be the first
consideration when using routers and other power tools.