What Is a Jointer?

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Marketing and misconceptions have led many woodworkers to think that as long as they have a planer, they don’t need a jointer. This is not entirely true. You should have both sets of tools because they go hand in hand. So, what is a jointer?

What Is a Jointer?

A jointer is a woodworking tool that essentially makes a board of wood flat, to not have a twist, bow, or cup defect. It derives its name from its function of providing flat surfaces on boards that you join together to produce even wider boards.

You shouldn’t confuse a jointer with a planer, which makes the boards have a uniform thickness. While both sets of tools are different, together they make the entire building process so much easier since you’ll have flat and uniform boards to work with.

Why Is a Jointer Important?

Hardly will you get every board you bought from the timber yard perfectly flat and straight. The various types of defects on boards are offset by changes in the environment when storing timber. 

Man explaining the difference between a jointer and a planer

While a planer is great for smoothing a board and reducing its thickness, it’s preferable to start with a board that’s flat and square. Or, as some woodworking circles call it, S4S, which stands for “surfaced on all sides.” 

With a good jointer, you can make your board flat on all surfaces, making it easier to join two boards together either by gluing, slotting, or screwing to create a frame or structure.

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How is a Jointer Designed?

A jointer essentially has two tabletops, coplanar to each other. A recessed cutter head separates the two sections referred to as the infeed table and outfeed table. This machine also has a fence (most are moveable) to ensure your angles are near perfect when lightly floating the board above the cutting head.

The blades in a jointer are set to match the elevation of the outfeed table. While operating the machine, the operator has to take care not to injure themselves due to the open design of the blades. Also, the operator should be hands-on, to maintain a suitable feed speed, while applying light and downward pressure.

The cutter head contains at least two or more blades, the more blades being better. The cutter head blades protrude outside to file the board coming into contact as the head rotates. The knives remove the excess amount of material parallel to the two tables, ensuring the board is flat along its length and perpendicular to the board’s face, thanks to the fence.

Types of Jointers

Close up of a jointer

There are essentially two types of jointers: 

  • Benchtop jointers
  • Stationary Jointers

We recommend benchtop jointers if your workshop is small or if you only work on smaller projects such as chairs or small boxes. In most cases, universal motors power benchtop jointers and have shorter beds in comparison to stationary variants. If you go with a benchtop, then choose one that’s at least 6-inch or more, with a decent motor size. 

Stationary (floor) models range from 6-inch and beyond, although up to 12-inch is more than enough for most people, unless running a good-size production shop. In general, an 8-inch jointer is great for most home woodworkers. Anything less might be limiting. Larger jointers are primarily used for industrial purposes.

What Are The Differences Between a Planer and a Jointer?

A common misconception is that a planer makes a board flat. On the contrary, you use a planer to make a board have a uniform thickness. Woodworkers categorize jointers and planers as preparation tools. This means you use them at the beginning of a project to help you achieve flat and uniform wood to work with.

In a planer, there are two feed rollers applying pressure under the block of wood, ensuring it stays flat along the deck. The rollers also double up to feed the planer itself. Unlike a jointer, the cutter head in a planer is set on top of the wood. The cylinder housing the cutter in a planer rotates at high RPMs, trimming the board as it’s fed through the machine.

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Another reason why some may confuse a planer with a jointer is due to linguistic differences. In America, most woodworkers refer to a jointer exclusively by the same name, whereas others in Europe and Australia may refer to it as a planer. However, neither woodworker would confuse the importance or use of either tool.

Man explaining what is a jointer

Do I Need a Jointer if I Have a Planer?

Do I Need a Jointer if I Have a Planer?

Your board must be flat first for a planer to work effectively, which you can achieve using a jointer. If you were to feed a planer a board with a defect, the wood would have a uniform thickness, yet the defect would only spring back up. The board cannot be flat without running it through a jointer first.

In some situations, you may get a nearly flat surface with a planer, only if the board is flat on one surface in the first place. The jointer thus creates a flat surface for the deck of the planer to reference, and creates a board with uniform thickness.

Are There Any Jointer Alternatives?

Fortunately, there are few other ways you can flatten out your board without a jointer, even though the process will be much slower and less efficient. If you’re good with a hand plane, you could just file one side of the rough board to make it flat, and run it through the planer with the flat surface lying down.

Another alternative is to use a sled for your planer. The sled supports and pushes the lumber as the feed rollers don’t push down the board to the table.

While not ideal, you can square a board with your jointer.

Finally, you can buy a planer jointer combo unit that will handle both for you.


With lumber that’s flat and uniform, it’s much easier to create a quality product. That is where a jointer comes in. It’s hard to get on with your woodworking projects without either. You need boards that are parallel to one another from either elevation. A jointer is just as important as any other tool in your arsenal.

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An expert at home repair, remodel, and DIY projects for nearly 40 years. His first experience came in completely restoring an antique home. Completely redone from the inside out, and restored to its original form, the home is a featured design by renowned Southern California Architect Cliff May, considered to be the father of the California Ranch Home. Now Dennis spends his time on fine woodworking projects and tool comparisons.