What's inside
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What a reference face does
A reference face is the first surface you make trustworthy on a rough board. You use it to set out measurements, guide a thickness measurement, or register the timber against a saw, plane, square, or marking gauge. It does not need to be polished. It does need to be flat enough, free of loose high spots, and clearly marked so you do not accidentally work from the wrong side.
On rough-sawn timber, the main mistake is trying to flatten the whole face immediately. A board may have twist, cup, bow, and milling marks at the same time. Removing every visible saw mark can waste substantial material. The practical aim is to establish a continuous, reliable plane over the useful part of the board, not to make a tabletop finish.
Choose the face and check the board
Start by deciding which face gives you the best result. Favor the face with fewer deep knots, less bark, and the least severe cup. If one face has a large hollow but the other has a modest crown, the crown is usually easier to remove. Check both faces with winding sticks or a straightedge before committing.
Mark the selected face with a broad pencil scribble or a cabinetmaker’s face mark: two short lines forming an arrow, with the point toward the reference face. Mark the adjacent reference edge later with a single line. These marks prevent a common failure: flattening one face, turning the board over, and then treating the unworked face as the datum.
Look along the board from both ends. A long straightedge will show bow, but it can hide twist. Place two equal-height winding sticks across the board, one near each end, and sight across their top edges. If the far stick appears tilted, the board is twisted. This check tells you where to remove material first.
Tools that make the job easier
A sharp jack plane is the main tool for most work. A cambered iron removes high areas without leaving harsh tracking lines, while a straighter iron gives more controlled shavings as the face approaches flat. A jointer plane can verify and refine a long board, but it is not essential for a short workpiece.
For badly rough timber, a scrub plane or a jack plane with a pronounced camber removes stock quickly. It also leaves a rougher surface and can dig holes if you work across the grain carelessly. A low-angle block plane is useful for end grain and small corrections, but it is inefficient as the primary tool on a wide board.
If you are buying rather than using an existing plane, compare the cost and the timber. A quality jack plane is worthwhile for repeated work. For one softwood project, a cheaper plane can be perfectly adequate if its iron is sharpened and the sole is reasonably flat.
| Tool | Best use | Main limitation |
|---|---|---|
| Jack plane | Initial flattening and general stock removal | Needs a sharp iron and sensible depth setting |
| Scrub plane | Fast removal from severely uneven boards | Leaves grooves and can gouge the face |
| Jointer plane | Checking and refining a long, straight face | Expensive and awkward on short pieces |
| Winding sticks | Finding twist across the board | Do not measure overall straightness by themselves |
| Marking gauge | Transferring a consistent thickness or layout line | Only reliable after a true face exists |
Flatten the high spots first
Use a pencil to cover the reference face with loose, widely spaced lines. Set the plane for a shallow cut at first. Plane diagonally across the grain, concentrating on obvious high spots. The pencil disappears from the high areas first, showing where the plane is working. Keep checking with the winding sticks; do not rely on the pencil alone.
When the board is twisted, remove the high corners that prevent the board from sitting on a common plane. Work the corner that lifts the most, then check again. Do not simply plane the entire board from end to end, because the plane will follow the existing twist and may leave the same twist with a smoother surface.
Once the high areas are reduced, plane diagonally in the opposite direction. Then take longer strokes along the grain, gradually reducing the cut. On a board around 1 metre long, a straightedge should show contact at several points along the length, with no obvious rocking. A small hollow of roughly 0.5 mm may be acceptable for rough construction, but a joinery reference face needs tighter control.
Control tear-out and blade problems
Read the grain before taking deep cuts. If the fibers rise toward you, planing in that direction may lift them ahead of the blade. Reverse direction, reduce the cut, or skew the plane slightly. On knotty timber, tear-out may be unavoidable; leave those areas until the face is nearly flat and use lighter finishing strokes.
Sharpening matters more than plane price. A dull iron forces you to push harder, makes the plane ride over high spots, and encourages deep, uneven cuts. For rough flattening, a working edge around 25 to 35 degrees is common, but the exact angle matters less than a clean, continuous edge. If shavings become dusty, ragged, or difficult to start, stop and sharpen.
Keep the plane sole clean. Resin and grit can make a decent plane drag and can scratch the face. A thin coat of suitable plane wax reduces friction, but do not use a waxed sole if the timber will later be glued or finished without removing the contamination.
Verify before using it as a datum
Check the face in three ways: sight along it, test it with a straightedge in several directions, and test for twist with winding sticks. The straightedge should not rock on isolated high spots. Place the board on a known-flat bench or surface and press at the corners; movement may indicate twist rather than a local bump.
Once satisfied, deepen the face mark so it remains visible. Now register a woodworking marking gauge from this face when laying out thickness or an edge. Keep the gauge fence firmly against the reference surface. A gauge set from an untrue face simply transfers the error accurately.
For a long workpiece, use a reliable woodworking straightedge rather than a random shelf edge. For occasional DIY work, a good aluminium straightedge is often sufficient; a precision steel rule is more useful when you routinely make cabinets, doors, or fitted joinery.
Common failure modes
If the face is flat in the middle but untouched at both ends, the plane was stopped too early or the board was supported unevenly. If both ends are low, too much pressure was applied at the start and finish of each stroke. Keep downward pressure over the board, not beyond it, and let the plane run off naturally.
If the board is flat but becomes too thin, you removed stock before deciding the required finished thickness. Measure the rough board, identify the minimum usable thickness, and mark a target line on the edges before heavy planing. A reference face is successful when it is dependable and leaves enough timber for the next operation—not when every saw mark has disappeared.