The bench plane is the most refined hand tool in the Western woodworking tradition, and it has barely changed in a century and a half. Yet a plane taken straight from its box is not really a tool at all — it is a kit of parts. The sole is rarely flat enough to trust, the cap iron arrives with a blunt, indifferent edge, and the frog sits wherever it happened to be when the box was sealed. Twenty minutes of fettling will transform it.

What you are chasing is a shaving you can read a newspaper through: continuous, translucent, and produced without effort. Everything below serves that single aim.

Flattening the sole

You need a flat reference. A 10 mm plate of float glass or a granite surface plate is ideal. Attach cloth-backed abrasive paper with spray adhesive and work through the grits: 80 only if the sole is badly dished, then 120, 180 and 240 to finish.

Before you start, colour the whole sole with a permanent marker. As you lap, the ink vanishes from the high spots and you can see exactly what you are removing. Use long, even strokes, keep the plane moving, and rotate it regularly so you do not introduce a twist.

Do not chase perfection. A working plane needs to be flat enough not to rock, and the critical zone is the 25 mm either side of the mouth — a hollow at the toe or heel is tolerable. Check progress with a straight edge and a 0.05 mm feeler gauge, and check the diagonals for twist. Stop when the feeler will not slide under anywhere near the mouth. Over-lapping a vintage sole opens the mouth and ruins it.

Fettling the cap iron

The cap iron is the most neglected component in woodworking, and it is the one that separates a plane that tears figured timber from one that leaves a glassy surface.

• Hone the leading edge at 45 to 50 degrees on a fine stone until it will shave a fingernail.
• Lay the cap iron flat on the stone and take two or three light strokes to remove the burr. Do not round the edge over.
• Hold it against the back of the iron and look towards a window. No light should show through the joint.
• Set it back from the cutting edge by roughly a third of a millimetre for a smoothing cut, or 1 to 1.5 mm for general work.

A tight cap iron set close to the edge controls tearout better than any other adjustment on the tool. If your shavings come off corrugated or the plane chatters, the cap iron is too far back.

Setting the frog and mouth

The frog carries the iron and the cap iron, and on the standard pattern it is held by two screws with a third to adjust its position. Loosen the two, turn the adjuster, and the frog slides forward to close the mouth or back to open it.

As a rule, the mouth should be just wide enough to pass the shaving. For a smoother on tricky timber, close it to about 0.5 mm. For a jack plane taking heavy cuts, 2 to 3 mm is plenty. Before you reassemble, check that the frog sits dead flush on its machined seat and that the face of the frog and the blade bed are clean and flat — a few strokes with a fine file here pays dividends. The cutting edge must sit square to the sides of the plane, or the lateral adjustment lever will have to fight the geometry for the rest of the tool's life.

Sharpening the iron

Grind a primary bevel at 25 degrees and hone a micro-bevel at 30. Work through a 1000-grit stone, then 6000, then 8000 or finer if you have it. Flatten the back of the iron at least once, working the first 25 mm until it is polished — a flat back matters as much as a sharp bevel.

A honing guide gives you repeatable angles; freehand sharpening is faster once your hands know the feel. Whichever you choose, keep the bevel flat across its width and finish by removing the wire burr. A few strokes of the flat face on the finest stone, or a pull through a scrap of softwood, will do it. The edge should slice newsprint cleanly with no snagging.

The test: whisper-thin shavings

Reassemble with the lever cap screw snug — firm enough to hold the iron, never so tight that it bows it. Retract the iron fully, then advance it with the adjuster wheel until it barely appears above the sole. Set the lateral lever so the edge is parallel to the mouth.

Take a light pass along a piece of straight-grained pine first. You are looking for a shaving around 0.05 mm thick that is translucent and comes off as a continuous ribbon. If it crumbles, you are too deep. If it corrugates, address the cap iron. If one side cuts and the other does not, your lateral adjustment needs a touch.

Then try a piece of figured oak or ash against the grain. That is the real examination, and it is where the work you have done on the cap iron earns its keep. Rub a candle stub along the sole to reduce friction, and always retract the iron before the plane goes back on the shelf. Look after it, and it will serve you for the rest of your working life — and quite possibly someone else's.