Being able to quickly plane boards
flat, smooth and to the exact thickness you need all make the
thickness planer one of the most important machines in any workshop's
power tool arsenal. But a planer is only useful if it's kept in
good running condition. Some of the regular maintenance tasks you
need to do include cleaning and lubricating the planer's bed and
running gear, keeping its knives sharp, and adjusting its extension
tables, depth stop and cutting thickness scale.
While shop machine cleanliness is next
to, well, you know, cleaning might be more important for thickness
planers than for any other shop machine. The reason is that a planer
with a dirty bed and sticky feed rollers may cause stock to not feed
smoothly--or not to feed at all. An accumulation of fine sawdust can
make it difficult to raise and lower the cutterhead, and chips
trapped inside the planer can jam up the entire machine.
Start cleaning your planer by first
unplugging it from power and then raising the head assembly all the
way up. Use your shop vacuum to clean sawdust from the bed and every
nook and cranny inside the body. A crevice tool (an accessory nozzle
that comes standard with many shop vacuums) can be very handy for
getting dust and chips that are stuck inside the planer. If the area around the cutterhead is packed
with chips, remove the dust shroud and vacuum that area thoroughly.
Once all the loose dust is gone, do a
quick visual inspection of the planer's bed and all components that
serve to raise and lower the planer's head assembly (or, on
stationary models, the bed). Clean dust and dirt that's accumulated
on any gears, screwposts, chains, etc. by first spraying them with a
cleaning solvent, then using a brush and rags to remove as much of
the grime as possible.
Spray the planer bed with solvent, too, if there's accumulated
pitch or other deposits. Use a ScotchBrite™ pad to remove hardened
deposits or corrosion (DO NOT use an abrasive pad if your planer's
bed is covered with a thin chromed steel sheet; the abrasive will
only scratch it and reduce its slickness). If you use a water-based
cleaner, such as Simple Green, be sure to dry all surfaces with a few
blasts of compressed air, to remove any remaining moisture that could
Next, inspect the planer's infeed and
outfeed rollers, and clean off any stuck-on deposits using alcohol
and a clean rag.
You can also use a cleaner like Simple Green® and a ScotchBrite pad
to remove stubborn deposits — just stay away from cleaning
solvents, such as naptha or paint thinner, as these could harm
rubber- or plastic-coated rollers.
To access the entire roller, clean
one section, then briefly plug the planer back in and flip the on
switch for just a second, until the rollers rotate around slightly.
Then unplug the machine and continue cleaning. Be VERY careful to
keep your fingers away from the cutterhead during cleaning;
alternatively, you could clean the rollers with the planer's knives
If the rollers are clean and you still
notice stock slipping during planing, check to see if the rubberized
surfaces of the rollers look shiny and glazed. You may be able to
temporarily improve their grip by sanding their surfaces slightly.
But eventually, such rollers will need to be replaced or recovered.
If you wish to lubricate any of your
planer's internal parts, make sure to use ONLY a dry lubricant,
such as Boeshield T-9®. Wet lubricants like oil or penetrating
sprays such as WD-40 will attract dust and cause more problems than
they solve. Before spraying, it's important to cover rubber feed
rollers with paper or rags, as coating them with lubricant will cause
them to slip and not feed stock effectively. Finally, don't try to lubricate your
portable planer's cutterhead bearings; these are permanently sealed
and lubricated. If they're making rumbling or grinding noises,
they're likely worn out—oiling them won't help.
To keep stock sliding smoothly through
a planer, it's most important to keep its bed and extension tables
well lubricated, either by spraying them with dry lubricant such as
TopCote®, or applying a coat of paste wax. If you choose waxing,
apply only a light coat of wax, let it dry until it hazes over, then
buff off the excess with a clean rag. I prefer liquid automotive waxes, as I find
that they're easier to apply and last longer than traditional
carnuba paste waxes. Cleaning and lubricating the bed/tables is a
maintenance task that may need to be done quite often, especially if
you often plane sappy woods such as pine.
SIDEBAR: How Do You Know When Your Planer Knives
The length of time it takes fresh,
sharp planer knives to dull depends on a myriad of factors: the
hardness of the steel the blades are made from (and how sharp they
were to begin with), the hardness of the wood you're planing and
how deep a cut you take, the planer's feed speed, and, naturally,
how many board feet of wood have been run. There are several telltale
signs that your planer's blades need changing.
If the blades have
been nicked, you'll notice small ridges forming on the surface of
(to deal with these, see the section "Changing the Knives" below). Somewhat dulled knives
tend not to cut as cleanly, especially on figured woods. If you
notice more tearout on such boards, it's likely your knives need
freshening. Really dull planer knives will actually burnish the
surface of plain-grained boards. If board surfaces look somewhat
shiny after planing, check by putting some water on the board (use an
open-pore, not-too-dense wood, like oak or mahogany, for this test —
not hard, resinous woods like teak or rosewood).
If the water
instantly forms small beads, it's likely the knives are really dull
and have burnished the wood. This can be a real problem, as a burnished surface
will actually repel water-based glues and finishes.
Changing the Knives
When your planer is no longer producing
clean, flat planed surfaces (see the sidebar, above),
it's time to refresh its knives. Fortunately, this process is very
easy for modern benchtop planers, which use reversible, disposable
knives that mount onto registration pins that automatically set each
knives cutting depth. (If you own an older or stationary model planer
which uses single-edged knives that require individual adjustment,
consult your machine's manual for removal and resetting
After making sure your machine is
disconnected from power, remove the planer's dust collection shroud
or chip chute, and any other body panels that cover or limit access
to the cutterhead. Once the cutterhead is fully exposed, rotate it until one of the
knives is facing fully upwards.
If your planer has an automatic
cutterhead lock, you'll have to depress it before turning the
will automatically engage when the knife is in the optimal position.
Now, either using the wrench that came with your machine or one that
fits, loosen all the bolts that secure the knife and its holder to
What you do next depends on what shape
your knives are in: If the knives are only nicked (see the sidebar, above), don't remove the
knife, but simply remove the knife cover and slide the knife slightly
to the left. Then clean the cover with a rag.
Refit the cover, then replace and carefully
tighten all the bolts. Advance the cutterhead to the next knife. Loosen its retaining
bolts, slide this knife slightly to the right, and re-secure the cover
and bolts. If there's a third knife, leave it alone. Shifting the
knives will offset the nicks and let you get a little more life out
of the set before it needs to be reversed or replaced.
Dull knives must be changed. For this
process, lift the knife out and either reverse it (if the opposite
edge hasn't been used yet) or replace it with a fresh knife. Some
planers come with special magnetic knife removal tools, which let you
handle the knife out without risking slicing up your fingers. If yours doesn't have one, you can use a
small horseshoe or bar magnet to do the job.
When refitting the knife
onto the cutterhead, take care to make sure that the small slots in
the knife slip onto the cutterhead's registration pins correctly.
the knife, use a little solvent to clean the knife holder of any dirt
or grime, and clean any bolts that are dirty as well.
reversed your knives, use a felt-tipped pen to mark each knife's
used edge, so you'll know not to reverse them next time. Reinstall the holder and tighten the bolts,
and repeat the process with each knife.
TIP: If you
really hate changing planer knives, one way to extend their life is
to make sure that each board you run is clean of mud and dirt and
free of staples, tacks or other metal fasteners.
the Belt and Chains
Before buttoning your planer's covers
back up, it's a good idea to check the condition of the motor's
drive belt, if it's visible. If the belt shows excessive wear or is damaged in
any way, replace it.
If your planer uses a chain-driven mechanism to
raise and lower the cutterhead assembly, clean the chain and
lubricate its links lightly with a drying lubricant. If the chain has
an accessible tensioning mechanism, tighten the chain up if it's
When you're done, replace the
cutterhead cover, shroud, and/or dust chute.
Leveling the Extension
One of the ways to combat planer
"snipe" (where the ends of a board end up with a depression or
are planed thinner than the rest of the board) is to make sure that
your planer's extension tables are level and in line with the bed.
Most portable planers have fold-down extensions that are adjustable
via a pair of small bolts or screws under their outside edges. To
check the level of your planer's tables, slide a long carpenter's
level or straightedge into the planer so that it lies on edge across
the bed and extension tables. Sight across each extension table, to see if
there's a gap at any point between the table and straightedge. If
necessary, tweak the table's adjustment bolts/screws until the
straightedge sits in full contact with the bed and table.
If the outfeed table can be adjusted up and
down, it's a good idea to set it just a fraction lower than the
planer bed. This prevents the lower edge of a planed board from
catching on the outfeed table. Once all table adjustments are made,
be sure to tighten the locking nut at the base of each adjusting
Set the Depth Stops
and Thickness Scale
Every planer has a scale and cursor to
show just how thick a board will be after planing. But if the cursor
setting is off, then you run the chance of ending up with stock
that's planed too thick or thin. Many modern portable planers also
have a depth stop feature that allows you to easily and accurately
set the cut thickness to one of several common sizes: 1/2 in., 3/4 in.,
etc. To check the accuracy of the stop mechanism, set it to one of
the middle settings, say 3/4 of an inch, and then plane a board. Use a
dial caliper to check the board's thickness.
If it's greater or less than 3/4 in.,
readjust the stop's depth rod. Recheck the stop's accuracy as before, and
tweak it as needed until it's dead-on.
Now, without changing the
planer's depth of cut, reset the planer's cursor, to read the
same thickness on the scale as your planed board (in this case, 3/4
especially important to check and reset the cursor after changing
knives, especially if your planer has older style knives that lack
registration pins in the cutterhead.