What is a Jointer Used For

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Picking up wood from the hardware store or lumber depot for a project can often cause disappointment. Unless you are paying extra for wood that has already been milled, you are bound to come home with wood that is slightly (or sometimes even extremely) bent, twisted, cupped, or otherwise warped.

The short answer to the question what is a jointer used for is to make these pieces flat.

What is a Jointer Used For

A jointer is primarily used to make flat surfaces on pieces of wood lumber. It does this by removing material on one side until the uneven wood has been removed, and all that is left is a flat, even face.

A freshly used jointer with remnants of sawdust on its body

A jointer does not create a consistent thickness along the edge of the wood, and in fact can be used to taper wood on purpose.

Uses for a Jointer

  1. Most pieces of wood can be made flat by the use of a jointer. This includes longer pieces that are bowed or twisted. If the piece of lumber is longer than the jointer table, one end is reduced and evened out first, then the same procedure is done with the other end.
  2. The back side of the jointer, or the “fence,” is a wall that you can lean the wood up against to flatten the short edges. This will square the edge 90 degrees. Some advanced tables also allow the fence to be aligned at different angles, but for the most part you will want a 90 degree angle between the flat and edge for your projects.
  3. Doors can be made true very quickly with the help of a jointer. In smaller jobs a hand plane can work well but perform slowly, while a jointer will make quick work of a door that is not square, or has excess material in a corner that needs to be removed.
  4. As previously discussed, the best jointer for the money is not specifically meant to create an even thickness in your plank – only flat faces. In the hands of a smooth operator, a taper can be created along the line of the wood for furniture like desk or table legs.

Parts of a Jointer

A jointer looks like one long table with a thin wall along the back edge. At first glance the table looks like one flat surface, but when you inspect it closely you will see that there are two separate tables, offset by just a little bit.

  • Infeed Table – the lower level table, usually to the right of the cutting area, where the wood starts. This table is often adjustable in order to change the depth of the cut.
  • Outfeed Table – this is the table on the higher side, where the wood is moved toward. Some advanced models allow you to adjust this table as well, but in most cases it should be left alone.
  • Fence – the back wall of the jointer. Coming from the factory, this is set at 90 degrees. By supporting an already jointed flat side against the fence, you can achieve a 90 degree angle from flat to edge. Always start by jointing the wide surfaces first.
  • Cutter Head – the cutting mechanism of the jointer. This is commonly made up of a series of knives attached along a spinning cylinder.

There are 4 main types of jointers available:

  1. Benchtop: a blend of open and closed stand, the best benchtop jointers are probably the most popular option.
  2. Tabletop: able to be set on a table in your shop, this is a heavier duty option compared to a benchtop.
  3. Closed Stand: most robust and durable with the most accurate cutting.
  4. Open Stand: smaller and more portable than a closed stand, these are perfect for a jobsite.
Close up image of a jointer

A Jointer is Different Than a Thickness Planer

While they both even out wood by removing material, a jointer and a thickness planer perform very different tasks. While a jointer creates one flat surface, a thickness planer creates a uniform thickness along the entire length of the piece of lumber.

You might think you could use a thickness planer to take the place of a jointer, but you would be wrong. While the planer also has an infeed and outfeed table, along with a similar cutting head, it also has heavy rollers that press down on the wood.

This flattens the wood as it goes through the machine, making sure that the distance between top and bottom never changes.

The reason this does not work for jointing is that with the wood being flat while going through the machine, none of the errors are corrected. What ends up coming out of the thickness planer is a piece of lumber with an even thickness along the entire length of the wood, but with exactly the same warping.

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Use a jointer in combination with a planer for the best results. Flatten the wood with a jointer first, being sure to joint the edges as well, before sending wood through a planer. There are some machines available that are a combination of the two – if woodworking is important to you and you do not have space for both machines, this may be a good option.

Why a Jointer is Important

In construction and other manufacturing processes where the bare lumber is rarely seen or noticed, or if it will be attached to supporting joints, minor warping is often not a big deal. Longer pieces are used, giving the possibility of them being corrected as they are supported all along their length.

In furniture making, fence building, and other professions where pieces of wood are placed together to make a larger, solid, flat surface, a jointer will make the entire job much easier. When using non-milled wood, the surfaces will not always match up exactly, and will need to be clamped in multiple places when joined.

Many times that will not be enough, and a planer will need to be used to even out any edges that protrude from the otherwise flat surface.

A jointer about to be used

Using flat, matching wood creates an even base, smoother surfaces, and gives you one less thing to worry about. The final product will look much better if there are fewer tool marks on the surface. The difference in manufacturing time between starting with flat pieces and warped pieces will also be quite pronounced.

Other Ways to Flatten Wood Surfaces

A jointer is essential in a woodworking shop, but it can be an expensive purchase for a home furniture hobbyist. Here are some other tools and methods to flatten wood surfaces that use the same concept as a jointer: removing excess wood.

  • Hand plane – Specifically a jointer plane, a larger, longer version of the standard hand plane. The original jointer before machinery came around, the long base helps even out warping and other deformities in wood.
  • Router sled – This is a DIY option that straddles the line between “this is brilliant” and “I may as well buy a jointer.” There are plenty of plans to build a sled online. The sled acts as a mount for a router, which you slide back and forth across the lumber, all down the length of the edge you are flattening.
  • Planer Jig – A DIY option that is worth looking into if you already have a planer. Mount the lumber you want flattened to another piece of wood, with blocks holding it in place, and shims leveling it. The planer will not bend the wood like it is designed to do, and you will get a decent jointer action out of it.
  • Belt Sander – Not the most accurate of methods, but with a T-ruler or metal straightedge you can approximate a decently flat surface.


There is sometimes confusion between a jointer and a planer since they both use the same basic principles, but the added heavy roller of the planer takes away the main thing that a joiner is used for – making flat surfaces on lumber. The combination of these two machines will remove many common problems for furniture makers and anyone tasked with joining multiple pieces of wood together.

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.