A marking knife leaves an incised line rather than a graphite mark, as Lee Valley puts it, and the line sits where the edge was. Across the grain the cut severs the surface fibres and gives a saw a place to start and a chisel a place to seat. Why that matters, and how to carry a knife line around a board, are explained in how to measure and mark accurately; this page is about the knife. A knife line is only as true as the square or rule it follows and the face it was measured from.
Parts of the knife
- Blade and edge. A thin blade ground to a cutting edge, often with a point or skew so the edge can reach into a corner.
- Bevel and flat face. On single-bevel and spear-point knives one side of the blade is flat; that face goes against the square or rule. Blue Spruce describes the bevel as steering the blade along the reference.
- Tip. Its shape decides which side of a reference the knife can work. Veritas grinds a 55° tip on both its knives.
- Handle. Shapes vary; Veritas gives the striking knife flats as a cue to which way the blade faces, and its shop knife suits both a pencil grip and a pistol grip.
Types of blade
| Blade | Edge | Against a reference | As one maker states it |
|---|---|---|---|
| Single bevel, right or left | One bevel, one flat face | Flat face on the reference puts the edge right at it; each hand of blade works one side of a reference | Blue Spruce sells single-bevel blades as a right- and left-hand pair |
| Spear point | A point formed by two edges, with a flat side | Flip the knife to put the flat side against a reference on either side | Blue Spruce: works equally well with the reference on the right or left; Veritas's shop knife blade flips end for end for flush registration either side |
| Double (dual) bevel | Bevelled on both faces | Usable from either side; held upright, its edge sits a little off the reference | Veritas: a dual bevel equally comfortable for right- or left-hand use |
These are the makers' descriptions of their own knives. Whether a spear point or double bevel works equally from both sides depends on that knife's grind and handle, not on the name.
A dovetail shows why the type matters: its lines run both ways from a reference, so a single-bevel user needs a left and a right blade, while a spear point or a double bevel can be turned to either side. The joint itself is in the dovetail guide.
| Knife | Steel | Blade | Bevel and tip | Overall |
|---|---|---|---|---|
| Veritas Workshop Striking Knife | A2 | Under 1/32 in thick, 5/16 in wide, about 1-1/2 in projecting | 25° bevel; 55° included tip; dual bevel | 6-5/8 in |
| Veritas Shop Knife | PM-V11 | 3/32 in thick, about 3/8 in wide, 1 in projecting | 25° bevel; 55° spear point; blade reversible | 6-3/4 in |
| Blue Spruce Classic Marking Knife | Not stated | .032 in, spear point; single-bevel pair available | Not stated | Not stated |
Figures are each maker's for its own knife and are not a recommendation for others. No steel is ranked here: a steel's name does not by itself say how a blade holds an edge or sharpens.
Using one
Knifing a line across a board
Set the reference
Hold the square's stock firmly on the reference edge, with the hand holding it behind the square and out of the knife's path.
Register the knife
Put the knife's flat face against the square's blade, with the edge on the mark — with a single-bevel knife, the left- or right-hand blade whose flat face meets the square on that side.
Draw the line
Draw the knife along the blade, keeping the flat face against it. Veritas suggests a pencil grip for fine control and a pistol grip for more force and a more visible line.
Check it
Make the line deep enough to see and to register a chisel or saw in; any depth left on a show face has to be planed or sanded out. Run a pencil along it if it is hard to see.
- Across the grain. The knife severs the surface fibres, which helps leave a clean edge at the line when the saw or chisel reaches it; it does not stop all tear-out.
- Along the grain. A blade can be pulled off line by the grain. For lines parallel to an edge — a tenon cheek, a rebate, a thickness — a marking gauge references the edge for you, and its cutting-gauge form uses a small knife across the grain.
- Starting the cut. How a chisel is set in a knife line, or a saw started against it, belongs to the chisel guide and the backsaw guide; mortise-and-tenon layout to the mortise and tenon guide.
Knife, gauge, awl or pencil
| Tool | What it leaves | How it is guided |
|---|---|---|
| Marking knife | A narrow cut line | By a square, rule or straightedge you hold |
| Marking or cutting gauge | A line parallel to an edge | By its own fence on the edge |
| Awl | A point — a hole centre, the end of a line | By eye, on a mark |
| Pencil | A drawn line with width | By a square or rule, or freehand |
None is better in every job: a pencil suits rough cuts and show faces, a knife the lines you cut to. The rest of the family is in the measuring and layout tools guide, and the carpenter's pencil in the carpenter's pencil guide. A utility knife or a carving knife is not a substitute: their blades are not made to run flat against a reference. Carving knives are covered in carving tools.
Care and sharpening
Keep the edge the maker gave it. Lee Valley advises honing the shop knife before first use, wiping the blade dry and applying a light coat of oil against rust, and storing it with the edge protected; the striking knife's guard stays on in storage. Keep a flat face flat as made, so it still lies against the square. Honing and sharpening edges in general are covered in how to sharpen chisels and plane irons.
Safety— Keep hands out of the knife's path
Hold the work steady and the square firmly, with the holding hand behind the square and never in the line the knife travels. Store the knife with its edge covered, and stop using one with a loose blade or a damaged handle. See woodworking safety equipment and woodworking safety rules.
Before knifing a line
- The mark is measured from the reference face or edge
- The square is checked and held firmly on the reference
- The knife's flat face, or the right-hand blade, faces the square
- The holding hand is behind the square, out of the knife's path
- A gauge is used instead for a line parallel to an edge
- The line will be cut to, or planed away, not left on a show face
Sources
Steels, thicknesses, bevel and tip angles are each maker's for its own knife and are shown side by side, not averaged or ranked; no maker states a single angle for all marking knives. Blue Spruce does not state its steel or bevel angle. How deep to cut and how many passes to make are not prescribed. Nothing was tested for this guide.
- 1.
Veritas Workshop Striking Knife. Lee Valley Tools (Veritas).
Used for: An A2 tool-steel blade less than 1/32 in thick and 5/16 in wide, projecting about 1-1/2 in, ground to a 25° bevel with a 55° included tip; a dual bevel equally comfortable for right- or left-hand use and for marking either side of a reference; an incised line rather than a graphite mark, to guide a saw or chisel; handle flats as a tactile cue to blade orientation; 6-5/8 in overall; the guard kept on in storage.
- 2.
Veritas Shop Knife. Lee Valley Tools (Veritas).
Used for: A PM-V11 blade 3/32 in thick and about 3/8 in wide with a 55° spear-point tip and a 25° bevel, projecting 1 in; a removable blade flipped end for end for right- or left-hand use and flush registration on either side of a reference; a pencil grip for fine control and a pistol grip for more force and a more visible line; scoring across the fibres more cleanly than a pencil; honing before first use, wiping dry with a light coat of oil, and storing with the edge protected; 6-3/4 in overall.
- 3.
Classic Marking Knife. Blue Spruce Toolworks.
Used for: A .032 in spear-point blade that works equally well with the reference on the right or left by flipping the knife, its flat side against the square or straightedge; the bevel steering the blade along the reference; single-bevel blades sold as a right- and left-hand pair; blades changed in a tool-less collet.
About this guide
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