How Does a Thickness Planer Work? Leverage the Knowledge for Quality Results

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For you to make the most out of your thickness planer, you require to understand how it works.

When you’re knowledgeable about how wood planers function, you’d be able to leverage their strengths to achieve quality results.

Hence, you can save considerable costs and time.

Not just that, but when you understand the workings of a wood planer, you’d be able to make correct purchasing decisions.

A planer is a thicknesser of wood – not a flattener.

Therefore, if you feed a warped board stock, it’d come out warped, only that it’s thinner than it was before.

And so, the planer works by shaving surfaces of board stocks, so both opposite faces run parallel.

As long as you’re familiar with how a wood planer operates, you won’t experience problems and confusions that come with using it.

You’d be able to avoid wasting pieces of wood, saving costs, given that the price of lumber is expensive.

Let’s attempt to answer the salient question, “How does a thickness planer work?”

Board Stock Depth

Most wood thicknessers trim board stocks up to a depth ranging between 3/32- and 1/8-inches with every pass.

Wood planers give you an option to set depth up to which you’d like to chop off material with one pass.

While it may tempt you to think that trimming more depth would reduce the number of passes, time and amount of work, in truth, deeper depths for a wider board stock can strain the motor.

Set the depth deeper for wider board stocks, and you strain the motor more.

Most thickness planers slice wood widths of between 12- and 13-inches.

If you plane work-pieces whose widths are less than 6-inches, we recommend you set depth to a maximum 1/16-inches for a single pass.

If you plane woods wider than 6-inches, set a maximum depth to be 1/32-inches per pass.

When you slice more material than less, you’d end up with a worse surface and it’d be difficult on the machine.

Necessary Tools

  • A well-functioning thicknesser
  • A jointer (to flatten at least one face)
  • Board stocks with more than one flat face
  • Dust collector
  • Marker pen or pencil
  • Ear and eye protection
  • Tight-fitting clothes

How a Wood Planer Works

And because a wood planer works by slicing certain thicknesses of material off of the wood piece, it’s perfect for milling and squaring up rough lumber.

Be sure to run through board stocks with rough surfaces on the top and flat surfaces on the bottom for quality results.

How a Wood Planer Works

Why is that the case?

Because the machine interprets the bottom surface as a reference point, modeling it as a template for trimming the top surface.

Therefore, if opposite faces running through the machine are either rough, uneven or not flat, the thicknesser would perpetuate (or even worsen) the imperfections of the bottom surface.

Think of a wood planer as construction that houses rollers with the middle roller (often called a cutter-head or a cutting head) having a set of knives (or blades) on its curved surface. Each knife is as wide as the length of the cutter-head.

But the length of the cutter-head is as wide as the maximum width of wood the device can cut through.

As in, for a machine with 12- ½-inch as the maximum wood width on the spec, that’s equivalent to the length of the cutter-head.

A Tri-Roller System

You’re most likely to encounter a tri-roller system in which the first (in-feed) roller grabs onto the board stock, pulling it through, and conveying it to the cutter-head (middle roller), which has knives, as you feed it into the device.

The third (out-feed) roller grabs onto the cut material, conveying it outside. The knife-bearing cutter-head slices the top surface up to the depth you set for a single pass.

Upon completion of trimming, the work-piece comes out of the machine with the assistance of an out-feed roller.

For optimal results, use a jointer to flatten the board stock before you place it on the in-feed table of the thicknesser.

The three rollers rest on a moving table, base or bed. And so, when you set depth, you’re essentially setting the height – a vertical distance between the base and the edge of the blade on the cylindrical roller.

Whereby in-feed and out-feed tables move, the first and third rollers move under their influence.

But not so with the cutter-head, which moves in the opposite direction under the influence of the motor.

As long as both the in- and out-feed rollers rotate clockwise, the cutter-head would rotate anti-clockwise.

With every pass, the board stock’s thickness reduces by the depths you set.

As deep depth as 1/8- or 1/16-inches can stretch the motor for a board stock wider than 6-inches.

You’d need to pass the work-piece several times to trim the material to a depth of your choice.


As you run a board stock through the thicknesser, you realize that either end of the top surface is slightly deeper than the rest.

In other words, the top surface is even on the middle but toward a bit deeper toward the edges facing the direction of feeding. This phenomenon is called a snipe.

You can’t completely eliminate snipe, but you can reduce it.

Snipe arises because the knives slice more thickness than necessary at the edges on the length along the direction of the feeding.

Sniping occurs as the roller on the in-feed table grabs onto the work-piece as it passes through the machine, and the roller on the out-feed table does the same, only to convey it outside.

As a board makes a transition between the rollers, the height changes slightly, making the board stock to slant a bit.

The secret to preventing sniping is to ensure the board stock moves exactly parallel to the surface as a cutter-head grabs it. Luckily, many planers nowadays have anti-snipe mechanisms.

But the bottom line is this: raise up one end of the work-piece facing you as you feed it into the machine.

Maintain that level as the first roller grabs onto the board stock, and raise it again as it comes out, so that the knives on the cutter-head don’t pull it back inside.

No Need to Visit a Lumberyard

Your main goal when using a planer is to save costs.

With correct use of a planer, you won’t need a lumberyard to prepare surfaces on your behalf. A wood planer doesn’t flatten your work-piece – that’s the job of a jointer.

What it does is to thickness wood, reducing material thicknesses by a certain margin for opposite sides to be parallel.

And so, if you pass through twisted lumber through the machine, don’t expect it to be flat, as it’d emerge just as warped as it was before, only thinner.

For quality results, use a jointer to flatten the bottom surface of the work-piece before you pass it through the machine.


This is Abraham. Professional power tools mechanic with years of experience. Writing is my hobby. So I decide to share my experience with people by writing about all types of power tools review and buyers guide that I'm using.

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