How do I cut a straight line in wood?
Marking, supporting and guiding — the three things that turn a wandering cut into a straight one.
- Difficulty
- beginner
- Time
- 20 min
- Read
- 2 min
- Safety
- warning
Short answer
Clamp a straight edge as a guide and let the saw run against it. Freehand cuts wander because there is nothing keeping them honest, not because of the sawing.
A straight cut is almost entirely about the setup. Marking accurately, supporting the wood so it does not pinch, and giving the saw something to follow does the work that technique cannot.
Safety
What you'll need
- Saw
- Straight edge or batten
- Clamps
- Pencil
- Square
- Eye protection
Step by step
- Mark the line properly with a square.A try square or a combination square, right across the face and down the edge. A line marked freehand is already a crooked cut.
- Mark which side of the line to cut.The saw removes material — its kerf. Cut on the waste side, or the piece ends up short by the blade's width. Hatch the waste side so you cannot forget.
- Support the wood on both sides of the cut.Two trestles or a workbench, with support either side. If the offcut is unsupported it drops and splinters the last part of the cut, and it can pinch the blade.
- Clamp a straight edge as a guide.A batten or a spirit level clamped parallel to the line, offset by the distance from the saw's edge to its blade. Run the saw base against it. This is what makes cuts straight.
- Start the cut with the blade on the waste side.Use your thumb knuckle as a guide for the first few strokes on a handsaw, then move it away. Start slowly — the beginning determines the whole cut.
- Let the saw do the work.Long steady strokes with a handsaw, steady feed with a power saw. Forcing it makes it wander and, with a power saw, is how kickback happens.
- Support the offcut at the end.Have someone hold it, or clamp it, for the last few centimetres. This is when the splintering happens.
- Score the line first for a clean edge.A knife cut along the line severs the surface fibres, so the saw does not tear them. Essential on veneered board and laminate.
Tips
- Masking tape along the cut line reduces splintering on veneered and laminated boards considerably.
- Cut with the good face up for a handsaw or circular saw, and good face down for a jigsaw. Blades tear on the exit side.
- Many merchants will cut sheet material to size, often free or for very little. For large panels this is both easier and more accurate than doing it at home.
Questions people ask
How do I stop a saw wandering off the line?
Clamp a straight edge as a guide and run the saw against it. Freehand cuts wander because nothing is keeping them straight.
How do I stop wood splintering when cutting?
Score the line with a knife first, apply masking tape along it, and support the offcut so it does not drop at the end of the cut.