How to Square a Board by Hand

Last reviewed on 2026-04-24

Squaring a board by hand — making a rough piece of lumber flat, square, and parallel on all six surfaces — is the foundation of hand-tool woodworking. Every joint begins with reference surfaces. If the first face is not flat, the joint that depends on it will not be straight. The traditional sequence for producing a squared board is called S6S ("surfaced six sides"), and it has been the standard in bench shops for well over a century because it works.

The S6S Process

1. Face 1 — flatten. Choose the less-damaged face and flatten it. Start with a scrub or heavily cambered jack across the grain to knock off high spots; follow with a jack plane diagonally and then along the grain; finish with a smoother if the surface will be seen. Check flatness with a straightedge in both directions and with winding sticks for twist.
2. Edge 1 — shoot square to Face 1. Clamp the board in a face vise with Face 1 toward you. Use a jointer or long jack plane to flatten the edge, checking with a try square set against Face 1. The edge is finished when it is straight along its length and square to the reference face.
3. Edge 2 — parallel at final width. Mark the final width from Edge 1 with a marking gauge, set from both faces. Plane down to the line, keeping Edge 2 square to Face 1. Check with the try square as you approach the line.
4. Face 2 — parallel at final thickness. Mark the final thickness with a marking gauge from Face 1, running the fence along both edges. Plane Face 2 down to the line. Scrub or cambered jack first if a lot of material must come off, then jack, then smoother.
5. End 1 — square to everything. Use a shooting board with a square fence to trim one end square to the two faces and two edges. See the shooting board guide.
6. End 2 — square at final length. Measure from End 1, mark, and shoot End 2 at the final length. Again, square to all other surfaces.

At the end of this sequence you have a board whose six surfaces are mutually square and whose dimensions match the drawing. This is the reference piece for the joinery that follows.

Why the Order Matters

Each step references the previous step. If Face 1 is not flat, there is no reliable reference for Edge 1. If Edge 1 is not square to Face 1, the rest of the part will not be square either. The sequence is not arbitrary; it is a chain of references.

Two rules reinforce the order:

• Once a surface is a reference, stop working on it. Touching up Face 1 after Edge 1 is done means re-checking Edge 1.
• Use a pencil mark to track which surfaces are finished. The traditional mark is a face mark (a scroll-like shape) on Face 1 and a matching edge mark on Edge 1 to indicate these are the two reference surfaces.

Tools You Need

• A scrub plane or a jack plane with a cambered iron for rapid face flattening.
• A jack plane or try plane for general face work.
• A jointer plane for edges (and long faces, if the stock is long).
• A smoothing plane for finishing faces.
• A try square (or engineer's square) at least 6 inches, ideally 12 inches.
• Winding sticks (two identical straight sticks) to check twist.
• A marking gauge for width and thickness.
• A shooting board for squaring ends.

Working Efficiently

Experienced hand-tool workers prepare several boards at once, doing the same step on all of them before moving to the next. All boards get Face 1 flattened, then all boards get Edge 1 shot, and so on. The tools stay set for each operation and the body motion stays consistent. This turns what feels like a slow job into something closer in pace to running a single board on machines.