Benchtop Thickness Planers
A benchtop planer is ideal for professional or hobbyist woodworkers with limited shop space, or who don't mill large quantities of lumber, and for contractors who want to be able to dimension stock on a job site. While they aren't designed for heavy duty continuous use, they excel at producing precisely milled, smoothly finished stock very quickly. This article provides an overview of some of the important features to consider when purchasing your first, or a replacement, planer. For your convenience, we also have a comparison table that provides baseline specifications, and links, to 17 popular models.
Maximum Cutting Width and Depth
The maximum cutting width of a planer is determined by the size of
its cutterhead, which is suspended below the motor and above the
planer bed (or table). The knives that attach to the cutterhead are the
same width as the cutterhead.
Planers come in 12", 12-1/2"
and 13" cutterhead widths. A decade or so
ago you would be hard pressed to find a planer with a 13" cutterhead. Today, they're the most common size, and it wouldn't come as a
surprise if manufacturers dispense with narrower cutterheads as
they bring new planer models to market. Wider, in this case, is better.
Maximum cutting depth is a non-issue, as all planers can mill stock
up to 6" thick (the Makita has a 6-3/32" capacity). One less thing
to clutter your mind with.
Depth of Cut
Manufacturers list the maximum amount of
material that planers can remove in a single pass. They generally
specify about 1/16" for stock that is the full width of the
cutterhead, and 1/8" for narrower stock (typically around 6" wide).
The simple reason is that removing more stock would place too much
strain on the rather small planer motor. When planing soft woods you
can go by the manufacturers recommendations, but with hard woods,
you'll place less strain on the planer's motor, and get a better
finish, if you take shallow cuts - 1/32 to 1/16". This isn't a
specification I would loose much sleep over.
Knives
There are two types of cutterheads. The conventional cutterhead uses
a straight knife (or blade) - this is what you'll find on the
majority of planers. Cutterheads with 2 knives are most common,
though three-knife cutterheads are becoming more widely available.
Having three knives on the cutterhead should make the knives last
longer between changes because there will be less wear on each knife
for the same amount of work done. All manufacturers, by the way, use
HSS (high speed steel) knives.
 Straight
knives - resharpenable |
 Straight
knives - reversible/self-indexing |
 Helical
cutterhead |
At one time manufacturers used thick (1/8") resharpenable knives. Increasingly however, they are using disposable reversible knives. These thinner (1/16") knives have a cutting edge on both sides, and when one side dulls you simply turn the knife around to expose the fresh cutting edge. My guess is that these are less expensive to manufacture. Regardless, when you factor in the cost of resharpening, reversible knives are price competitive. Remember that these disposable knives are recyclable.
Recently, Steel City and General have introduced planers with helical cutterheads, which use small square cutter knives arrayed in a spiral wrap around the cutterhead. The cutters on these planers are 2-sided - when a cutter becomes worn or is chipped, you rotate it to expose a fresh side. In busy shops this is a real benefit, as it reduces down time. The cutters are made of carbide steel, which hold an edge longer than HSS. Helical cutterheads also run quieter than conventional cutterheads and they produce less tear out on lumber with wild grain. As with conventional cutterheads, they do leave milling marks on stock that needs to be sanded or hand planed before a finish is applied.
Knife Changing
It used to be that changing knives was irksome and time consuming. No so today. Most manufacturers use self-indexing (quick change) knives. The knives have elongated holes that enable you to simply drop them onto registration pins on the cutterhead. A cutterhead with self-indexing knives is a thing of beauty.
 Changing
knives on many planers is relatively straightforward |
 Cutters
are easy, but more time consuming, to install |
Rotating or swapping out cutters on a helical cutterhead is very
easy, though perhaps somewhat more time consuming, as there are 26
cutters to deal with.
The cutterhead has a tendency to
move as you unscrew the knives. Some planers have a lock that keeps the cutterhead from
moving. Not a deal breaker, but a nice feature to have.
Feed Rate
The feed rate is the speed, measured in feet per minute (FPM), that
stock passes through the planer. The most common feed rate is
26 FPM. This is somewhat of a compromise rate that meets the needs
of contractors and cabinet makers better than the needs of furniture
makers. It's a moderate feed speed that processes stock fairly
quickly and delivers a reasonably good
finish, quite suitable for stock that will be painted. If you work
primarily with hard woods, especially those with interlock grain, a
slower feed rate will give a better finish. Fortunately, there are a
few planers that have dual feed rates - a low 14 to 18 FPM rate, and
a faster (usually 26 FPM) rate.
Cuts Per Inch (CPI)
There is a specification that you'll want to pay attention to. The
CPI is affected by the feed rate (FPM), the number of knives on
the cutterhead, and the motor speed (RPM). Rather than being overly
concerned with these three individual factors, keep an eye on the CPI - the
more cuts per inch, the
better a finish you can expect. A 2-knife planer that cuts at 96 CPI
will give a finish as clean as a 3-knife planer with the same CPI.
The knives on the 3-knife planer will probably stay sharper a bit
longer because each knife is doing less work.
Motor
All planers, save a lonely Craftsman, use 15-amp universal motors.
They're light, loud, inexpensive to manufacture, and they can run
on a standard 110/120-Volt circuit. Excessive heat is the number one
enemy of universal motors, so most are now equipped with
thermal overload protection, which will automatically shut the motor
down when it reaches a critical temperature - and before it
overheats. This is a feature you don't want to overlook. That's
really all you can tell about a planer motor, as manufacturers don't
necessarily provide NEMA (National Electrical Manufacturers Association) or IEC
(International Electrotechnical Commission) ratings on their web
sites. The ratings
can be found on the motor nameplate (though the motor is often
enclosed in a housing). For more information on motors
read Siemens excellent primer.
Anti-Snipe Locks
Snipe is the shallow depression that occurs at the front or rear of
a board after it passes through the planer. It can be caused by a
board entering the cutterhead with the front or rear of the board
elevated, or by vibration of the cutterhead assembly. Anti-snipe (or
cutterhead) locks do help stabilize the cutterhead, though they
don't completely eliminate snipe, particularly on very long stock or
thin stock. To increase stock support, some manufacturers include
in-feed and out-feed tables.
 Snipe
on the end of a board |
 One
style of cutterhead lock |
Depth Stop
The depth stop (or depth lock) on a planer is very similar to that found on a plunge
router. You can select, from a range of specific thicknesses, the
depth below which you can't lower the cutterhead. Not all planers
offer this feature. Others provide three or four stops, while a few
models provide a fairly wide range, from 1/8" to 1-3/4". For quickly
processing lumber to specified thicknesses, a depth stop is a handy
feature to have. However, you need to keep you planer clean, as dust
and debris can clog up the mechanism. For precision work, it's still
a good idea to rely on calipers to confirm your final thickness.
Material Removal Gauge
The material removal gauge (or depth-of-cut indicator) lets you know
how much material will be removed in a single pass through the
planer. Most planers use an inverted pin that takes a measurement at
a single spot. However, a pressure bar that runs the full width of
the planer, on the infeed side, provides a more accurate indicator
of the depth-of-cut. In any event, it's a good idea to remove no
more than 1/16" to 1/32" on each pass.
Thickness Scale
The thickness scale (or vertical depth scale) displays what will be
the stock thickness after running through the planer. Some scales
are difficult to read, and the graduations on the scale coarse.
Don't assume the scale is accurate - more than likely you'll need to
calibrate the scale when you first purchase the planer, and
intermittently thereafter. You can also add a digital readout scale
(see Planer
Accessories).
 Depth
Stop |
 Material
Removal Gauge |
 Cutting
Depth Scale |
Noise Level
Planers are among the worst noise polluters in a workshop, so
hearing protection is vital - regardless of the planers rated
decibel level. Sustained exposure to noise between 90
and 95 decibels can result in hearing loss, and noise levels from
planers can be as high as 105 decibels. Planers with helical
cutterheads are somewhat quieter, though hearing protection is still
mandatory.
Extension Tables
To reduce snipe, it's important that stock is fully supported before
and after it passes under the cutterhead. Which is why most planers
comes with both infeed and outfeed tables. Longer tables are always
better. Ideally you want extension tables
can be easily adjusted level with the planer table, and angled
upwards or downwards at their ends. However, extension tables don't,
by themselves, eliminate snipe. For that, you'll want to read our
tips on Taming Snipe, below.
Dust Collection
Planers can generate huge amounts of sawdust, so being able to
efficiently manage the waste is important. Oddly enough, a few models are not
equipped with a dust port, or offer it as an optional add-on. The
wood chips just spew out the outfeed side of the planer. This
might be suitable if you mill very small quantities of wood, and
don't mind sweeping up after each use of the planer.
Other models do come with at least a 2-1/4" or 2-1/2" dust port, to which you
can connect a shop vacuum. However, shop vacuums are not designed to
handle the large volume of wood chips that planers generate - the
small diameter hoses can quickly clog up, and the vacuum canister
will fill up very quickly.
Planers that include a 4" dust port enable
you to connect to your shops dust collector. If you regularly mill
lumber, this is by far the best way to manage planer
waste.
 Without
a dust port installed, wood chips scatter everywhere |
 With
a 4" dust port you can connect to your shop's dust collector |
Return Rollers
Stock return rollers are included on some planers. They can be in
the form of steel rollers or aluminum rails, and are located on top
of the planer.
They make it somewhat easier to transfer stock back
to the infeed side of the planer. This is quite convenient if you're
milling a lot of stock.
Weight
Planers range in weight from about 50 to almost 100 pounds. The
lighter models can probably be called portable. In most shops they
are mounted on a wheeled table - so they can be moved around the
shop or out of the way when not in use - or they are regulated to a
stationary cart. Unless you regularly transport a planer to and from
a job site, planer weight shouldn't be much of a concern. In fact, a
heavier planer will likely be subject to less vibration.
Warranty
As with any portable or stationary
power tool, a longer warranty is preferable. Warranties range from 1
to 5 years. The price differential between a 1-year and 5-year
warranty is pretty economic insurance, particularly if you use your
planer on a daily basis. Note however, that most manufacturers don't
warranty these planes for commercial use.
Picking the Right Thickness Planer
The right planer for you will depend, among other things, on the
kind of work you do and the budget you have available. The features
that we feel are most important to look for include:
- 3-knife cutterhead (helical cutterhead for a full-time woodworker)
- Self-indexing, reversible knives
- High CPI (cuts per inch)
- Anti-snipe lock
- Wide range of depth stop settings
- Wide extension tables that are easy to adjust
- 4" dust port
- Multi-year warranty
Taming Snipe
There are several ways you can minimize snipe.
- Feed your stock through the thickness planer butt-end to butt-end. However, feed a sacrificial board (the same thickness as your stock) as the first board, and then again as the last board. Any snipe will occur on the sacrificial board. Remember to keep the stock butted together - if there is a gap between boards you run the risk of snipe.
- Support long boards with roller stands on both the infeed and outfeed ends. This is particularly useful when milling long, heavy timbers.
- Place thin stock (3/4" or less) on a sub-base before feeding it through the planer. You can wedge thicker pieces in place, or use double sided tape to secure thin stock.
- Install a long auxiliary bed through the mouth of the
planer and over the infeed and outfeed tables. Go to our
Planer Resources page for a
link to Fine Woodworking magazine's free 'Shopmade Planer Table'
plan.
 Planer
Sub-Base |
 Planer
Auxiliary Table |
Planing Tips
Planers are quite safe, and easy to use.
To get the best results, while maximizing your health and safety, follow these helpful
planing tips.
- Wear ear protectors, a respirator, and safety glasses.
- Avoid planing stock less than 8" long. Short pieces can get caught up between the cutterhead and pressure rollers.
- If you plan on milling recycled lumber use a metal detector to check for metal objects.
- Make sure that the planer's extension tables are level and in line with the bed. Some people find that tilting the ends of the extension tables so that they are slightly above the level of the bed helps reduce snipe.
- Take no more than 1⁄16" to 1⁄32" off your stock on each pass. This puts less strain on the planer motor, and helps reduce tearout.
- Clean the planer bed frequently with a dry coat lubricant or wax, and clean the feed rollers whenever they begin to clog up with debris. This will help ensure your stock isn't scratched by debris as it moves through the planer.
- Replace the blades when you notice that your stock is no longer producing clean, flat surfaces.
- Unplug the power cord before changing knifes.
- Joint one side before running a board through the planer.
- Whenever possible, feed the board at a slight angle to the knifes.
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