Saw Making and Maintenance

Part of Woodworking

A saw does what no axe or chisel can — it cuts wood in a straight line, with minimal waste, to a precise dimension. Without saws, you are limited to splitting and hewing, which follow the grain wherever it goes. Building a saw from scratch is one of the more demanding toolmaking tasks, but the payoff is enormous: accurate lumber from raw logs.

Why Saws Matter

Consider what you cannot do without a saw:

• Cut a board to exact length without splintering
• Rip a plank from a log with uniform thickness
• Cut joinery (tenons, dovetails) with clean shoulders
• Build anything that requires flat boards

Splitting with wedges follows the grain, producing rough, uneven surfaces. Hewing with an axe wastes material and leaves a wavy surface. A saw cuts where you want, how you want, regardless of grain direction.

Types of Saws to Build

Saw Type	Frame	Blade	Best For
Frame saw (turning saw)	Wooden H-frame with twisted cord tension	Narrow blade, 50-80 cm	General cutting, curves
Bow saw	Curved wooden frame	Narrow blade, 30-50 cm	Curved cuts, smaller work
Pit saw	Two handles, no frame	Wide blade, 150-200 cm	Ripping logs into planks (2 people)
Back saw	Wooden handle, steel spine	Short blade, 20-30 cm	Fine joinery, tenon shoulders

Start with the frame saw — it is the most versatile and the easiest to build.

Frame Saw Construction

The frame saw is an H-shaped wooden frame that holds a thin blade under tension. The tension is provided by a twisted cord (a Spanish windlass), not by the frame itself.

Parts

• Two arms (cheeks): hardwood, about 40-50 cm long, 4 cm square
• One stretcher (crossbar): hardwood, 50-70 cm long, connecting the arms at their midpoints
• Blade: steel strip with teeth, 50-70 cm long
• Two blade pins: steel or hardwood dowels that hold the blade ends in the arms
• Tension cord: strong twine or thin rope across the top of the arms
• Toggle stick: a short stick twisted into the cord to increase tension

Assembly

1. Drill or burn a hole through each arm near the bottom for the blade pins
2. Cut a mortise in each arm at the midpoint for the stretcher
3. Fit the stretcher into the arms — the joint should be snug but allow the arms to pivot slightly
4. Attach the blade to the pins at the bottom of each arm
5. Tie the tension cord between the tops of the arms
6. Insert the toggle stick into the cord and twist until the blade is taut
7. Rest the toggle against the stretcher to hold tension

Tip

The blade should “ping” when plucked — a dull thud means insufficient tension. A loose blade wanders in the cut and binds. More tension is almost always better, up to the point where the arms start to bow inward.

Making a Saw Blade

This is the hardest part. A saw blade must be thin enough to cut without excessive waste, hard enough to hold sharp teeth, and tough enough not to snap under tension.

Material

• Best: old bandsaw blades, hacksaw blades, or circular saw blade segments — already the right steel
• Good: flat spring steel (clock springs, tape measures, feeler gauges)
• Acceptable: sheet steel from old hand saws, scraped and re-toothed

The blade should be approximately 0.5-1.0 mm thick, 15-30 mm wide (wider for rip saws, narrower for curve-cutting).

Cutting Teeth

Teeth are cut into the blade edge using a triangular file (also called a saw file or taper file).

1. Clamp the blade in a vise or between two boards with the edge exposed
2. Mark the tooth spacing — use a ruler or wrap-around template
   • Fine crosscut: 3-4 mm spacing (8-10 teeth per inch)
   • Coarse rip: 5-7 mm spacing (4-5 teeth per inch)
3. File each tooth gullet (the valley between teeth) to uniform depth — about half the tooth spacing
4. File at a consistent angle across the blade

Tooth Geometry

This is critical. Crosscut teeth and rip teeth have fundamentally different shapes because they do fundamentally different jobs.

Crosscut teeth sever fibers across the grain:

• Filed at 60-65 degrees to the blade face
• The tooth points act like tiny knife edges
• They score two lines and the waste crumbles out between them

Rip teeth chisel fibers along the grain:

• Filed at 90 degrees (straight across) to the blade face
• Each tooth acts like a tiny chisel
• They scoop out material in the direction of the cut

Warning

A crosscut saw used for ripping will work, just slowly. A rip saw used for crosscutting will tear the wood badly. If you can only make one saw, make it a crosscut — it handles both tasks acceptably. Dedicate a second saw to ripping when you can.

Setting the Teeth

If the saw teeth are the same width as the blade, the blade will bind in the cut — friction on both sides locks it in place. Setting the teeth solves this.

Setting means bending alternate teeth slightly left and right, so the cut (the kerf) is wider than the blade body.

How to Set Teeth

1. Clamp the blade firmly
2. Using a punch, nail set, or dedicated saw set tool, bend tooth #1 slightly to the left
3. Skip tooth #2
4. Bend tooth #3 slightly to the left
5. Flip the blade (or work from the other side)
6. Bend tooth #2 slightly to the right
7. Skip tooth #3
8. Bend tooth #4 to the right
9. Continue alternating

The amount of set depends on the wood:

Wood Type	Set Amount (each side)
Dry hardwood	Minimal — 0.1-0.2 mm
Dry softwood	Moderate — 0.2-0.3 mm
Green (wet) wood	Generous — 0.3-0.5 mm

Tip

Too little set causes binding. Too much set makes a wide, wasteful kerf and requires more effort. Start with less set and increase if the saw binds. You can always add more set, but removing it means re-filing the teeth.

Sharpening a Saw

Saws need regular sharpening — a dull saw requires exhausting effort and cuts crooked.

What You Need

• A triangular (three-square) file, sized to fit the tooth gullets
• A saw vise or two boards clamped together to hold the blade
• Good light
• Patience

The Process

1. Joint the teeth — lay a flat file along the tooth tips and take one light pass. This reveals the height of each tooth (bright spots on the tips show which teeth are too long, untouched tips are too short)
2. Shape the teeth — file each gullet until all teeth are the same height and shape. File at the correct angle for crosscut or rip
3. Set the teeth — after shaping, apply set as described above
4. Final light pass — one more stroke per gullet to clean up any burrs from setting

Filing Direction for Crosscut Saws

File every other gullet from one side (angled about 15-25 degrees from perpendicular), then flip the blade and file the remaining gullets from the other side at the same angle. This creates the alternating knife-edge geometry that crosscut teeth need.

Filing Direction for Rip Saws

File every gullet straight across (perpendicular to the blade). No angle needed. This is simpler than crosscut filing.

Building a Saw Vise

A saw vise holds the blade firmly at the right height for filing. Without one, sharpening is miserably difficult.

1. Take two boards, about 40 cm long, 10 cm wide, 2 cm thick
2. Hinge them together at one end (a leather strip nailed across works)
3. Clamp the blade between them, teeth protruding 1-2 cm above the boards
4. Clamp the whole assembly in a bench vise or between two posts

The boards dampen vibration, which makes filing smoother and quieter. Teeth that chatter under the file produce inconsistent results.

The Bow Saw

A bow saw is a smaller, lighter version of the frame saw, designed for curved cuts.

• The frame is a single piece of bent green wood (hazel, ash) or a steam-bent strip
• The blade is narrower than a frame saw blade (6-12 mm) to navigate curves
• Tension is provided by twisting a cord across the open end, same as a frame saw
• Ideal for cutting chair parts, boat knees, and decorative curves

The Pit Saw

For ripping logs into planks, a pit saw is the traditional solution before powered sawmills.

Setup

1. Position a log over a pit or on a high trestle (the log must be above head height)
2. One person stands on top of the log (the tiller) — they guide the cut along a snapped chalk line
3. One person stands below (the pitman) — they pull the saw down on the cutting stroke
4. The saw is a long, wide blade (150-200 cm) with a handle at each end
5. Rip teeth, coarse spacing (4-5 per inch)

Operation

• The tiller guides accuracy, keeping the blade on the line
• The pitman provides power on the downstroke
• Both release pressure on the upstroke
• Wedges are driven into the kerf behind the saw to prevent binding
• Progress: expect 1-2 meters of cut per minute in softwood, less in hardwood

Warning

The pitman gets showered with sawdust continuously. In historical sawpits, this was the worst job in the shop. Position yourself upwind when possible, and take breaks to clear eyes and lungs. Wrap a cloth around your face.

Maintaining a Saw Blade

Preventing Rust

• Wipe the blade with an oily rag after every use
• Store in a dry location
• A light coat of wax (beeswax rubbed on) prevents rust and reduces friction during cuts

Dealing with a Warped Blade

Thin saw blades can develop kinks or bows.

• Lay the blade on a flat surface (anvil, flat stone)
• Identify the high spot (the blade rocks on it)
• Tap the high spot lightly with a hammer — this stretches the metal slightly and flattens the area
• Work gradually — aggressive hammering creates new problems

When to Re-tooth

If teeth are badly damaged, uneven in height, or the wrong geometry for your work, it is faster to grind the teeth off entirely and re-cut them from scratch than to try to fix individual teeth. Joint the edge flat with a file, re-mark tooth spacing, and re-cut.

Troubleshooting

Problem	Cause	Fix
Saw wanders in cut	Uneven set, dull teeth, or too little tension	Check set on both sides, sharpen, tighten frame
Saw binds	Not enough set, green wood swelling, or kerf closing	Add set, use wedges behind the cut
Rough cut surface	Teeth too coarse, wrong tooth geometry	Use finer teeth, verify crosscut angle
Saw takes excessive effort	Dull teeth, too much set, poor technique	Sharpen, reduce set, let the saw do the work
Blade breaks	Over-tensioned, kinked blade, forcing a curve	Reduce tension slightly, replace blade, use a narrower blade for curves

Saw Making and Maintenance — At a Glance

Build a frame saw first — an H-shaped wooden frame with a thin steel blade tensioned by a twisted cord. Source blade steel from old saw blades, spring steel, or sheet metal. Cut teeth with a triangular file: crosscut teeth at 60-65 degrees for across-grain cuts, rip teeth at 90 degrees for with-grain cuts. Set the teeth (bend alternating teeth left and right) so the kerf is wider than the blade body. Sharpen regularly by filing each gullet to uniform depth and shape. For ripping logs into planks, build a pit saw — a two-person operation over a pit or trestle. Keep blades oiled, properly tensioned, and stored dry.