What Is A Jointer Plane

A jointer plane is the longest bench plane — the No. 7 at about twenty-two inches, or the larger No. 8 at about twenty-four. That length is its entire reason for being. A jointer exists to make a long edge genuinely straight, so two boards close tight along their whole length for a glue-up, and to flatten large panels a shorter plane would only follow. It is the specialist at the top of the range, and the one most benches add last.

What the length actually does

A plane sole is a straightedge with a blade in it, and it can only make a surface as straight as the sole itself is long. Run a two-foot jointer down the edge of a board and the long sole spans the whole edge: it ignores a shallow dip in the middle, rides on the high spots, and shears them down until the edge is straight from end to end and the plane stops cutting because there is nothing left standing proud. Run a short plane down the same edge and it registers on a smaller span, so it follows the gentle curve already there — it flattens locally but does not straighten globally. That difference is the whole case for a jointer, and it is why a long plane is the only one that reliably straightens a long edge.

Its two jobs: edges and panels

The headline job is edge-jointing: truing the mating edges of boards so they glue up into a wide panel with an invisible seam. Any curve left in an edge shows as a gap when the two boards meet, and the eye reads a glue line mercilessly, so this is the job where the jointer's length earns its keep and a shorter plane starts to struggle. The second job is flattening wide or long panels— a table top, a door, a glued-up slab — where the long sole spans the surface and trues it rather than chasing every dip. For everyday face flattening a jack is enough; the jointer comes out when the work is long enough that a shorter plane would leave a curve.

How to joint an edge square

Jointing is a technique as much as a tool, and it is worth spelling out:

1. Clamp the board edge-up in a vise, high enough that you are not stooping, with room in front of and behind the work for the plane to travel on and off.
2. Take full-length passes and let the long sole find its own reference. As it rides the high spots it removes them, and each pass brings the edge closer to a line the sole is happy to sit on.
3. Keep the plane square to the face. Center your weight over the sole and let the edge guide you; some woodworkers hook fingers under the sole as a fence, or use a jointer fence, to hold it perpendicular.
4. Check as you go with a straightedge along the edge and a square across it, and test the real fit by standing the two boards together and looking for light between them.
5. Consider a spring joint— taking a whisker more from the middle than the ends — so the boards touch first at the ends and pull tight in the clamps.

The plane does the flattening; your reading of the edge does the straightening. Getting the plane itself set true first matters here more than anywhere, because a long sole that is not flat cannot make a straight edge — work through how to set up a hand plane before you rely on one for a glue line.

No. 7 or No. 8?

The No. 7 for almost everyone. It is long enough to joint any edge a home shop realistically glues up and heavy enough to carry the cut without being punishing over a session. The No. 8is longer and noticeably heavier, for marginally straighter results on very long stock, and that extra mass is genuinely tiring — it is a want, not a need, unless you joint long edges all day. The still-useful in-between is the No. 6 fore plane at about eighteen inches, long enough to joint most edges and short enough to double as a heavy flattener, which makes it a fair single compromise for someone who does not want a full jointer.

Do you actually need one?

Many woodworkers never buy a jointer, and that is a defensible choice. A No. 5 jack, backed by a straightedge and a little patience, joints shorter edges well enough, and a No. 6 covers most of what a home shop glues up. You reach the jack's limit when the boards get long — joint a six-foot table edge with a fourteen-inch plane and the accumulated error becomes a visible gap. The honest rule: buy the jointer the day a long glue line disappoints you, not before. The full comparison of where the jack stops and the jointer starts is in jack plane vs jointer plane, and where every number falls is in plane numbers explained.

Buying a jointer, new or used

The jointer is the plane where the secondhand market is kindest. Long planes are expensive new and heavy to ship, so a vintage No. 7 in usable shape often costs a fraction of a new premium one and is frequently a better casting. Budget an evening to true the sole — the longer the sole, the more its flatness matters — and to fit a good iron. New jointers run from entry-level to premium, and because the jointer is used least often of the set, a sound vintage example is usually the sensible buy. Which jointers are worth owning, old or new, is ranked on the best hand planes. Bought once and kept flat, a jointer is a tool your grandchildren could joint an edge with.