The Definitive Guide to Reciprocating Saw Blades: Engineering, Application, and Selection

1. Introduction: The Engine of Demolition

The reciprocating saw is often called the "king of demolition." Professionals rely on it for everything from framing to plumbing. However, the saw itself is just the engine. The blade is the tyre that meets the road.

Without the correct blade, even the most expensive saw is useless. Using the wrong blade leads to snapped shanks, ruined materials, and dangerous kickbacks. Conversely, the right blade transforms a rough demolition tool into a precision instrument.

This guide goes beyond basic selection. We will analyse metallurgical compositions, dissect tooth geometry, and define the physics of chip evacuation.

Our goal is to elevate your knowledge from basic user to industry expert. We will also highlight the manufacturing excellence of (https://www.johnsontoolscn.com/), a global leader in OEM/ODM blade solutions with over 20 years of experience.

2. The Physics of Reciprocating Cutting

2.1 The Linear Stroke Mechanism

Circular saws cut with continuous momentum. Reciprocating saws are different. They rely on a violent push-and-pull stroke. This linear motion creates unique physical stresses on the metal.

The blade must withstand opposing forces. It faces compression on the push stroke and tension on the pull stroke. This cycle repeats thousands of times per minute (SPM).

The standard stroke length ranges from 1-1/8" to 1-1/4". This distance is critical. It defines how many teeth enter and exit the cut with each cycle.

A blade that is too short is dangerous. If the tip does not clear the material on the backstroke, debris packs into the gullets. This "chip packing" generates immense heat. It ruins the blade's temper instantly.

A blade that is too long is unstable. Excess length acts as a lever arm. It increases vibration at the tip. This "whip" effect reduces accuracy and increases the risk of the blade buckling.

2.2 Chip Load and Evacuation

Sawing is not slicing; it is chiselling. Each tooth acts as a tiny chisel. It gouges out a small chip of material.

The gullet is the valley between the teeth. It acts as a bucket. It must carry the chip out of the kerf (the cut slot).

Chip evacuation limits your cutting speed.

• In Wood: Chips are large and fibrous. They require deep, spacious gullets. If the gullet is too small, the wood compresses. The blade binds, friction spikes, and the wood burns.

• In Metal: Chips are small and hot. They require shallow, reinforced gullets. The primary goal is to shear the metal without snapping the tooth.

2.3 Harmonic Vibrations

Physics dictates that every object has a natural frequency. When a constant-pitch blade cuts hard metal, it can establish a rhythm. This creates a harmonic resonance.

Operators feel this as "chatter." The blade bounces violently against the workpiece. It screams with noise and leaves a washboard finish.

Variable Pitch Technology solves this.

Engineers design blades with shifting TPI patterns (e.g., 10/14 TPI). The distance between teeth constantly changes. This disrupts the harmonic wave. The blade never settles into a destructive rhythm, resulting in a smoother, cooler cut.

3. Metallurgical Composition: The Backbone of Performance

The soul of the blade is its steel. The manufacturing process determines flexibility, hardness, and thermal resistance.

3.1 High Carbon Steel (HCS)

HCS is the foundational material. It is basic steel with elevated carbon content.

• Characteristics: Highly flexible. It bends without snapping.

• Best Use: Softwoods, plastics, and low-stress DIY tasks.

• Critical Weakness: Low heat resistance. It loses hardness at relatively low temperatures. It is useless against metal. If an HCS blade hits a nail, the teeth strip immediately.

3.2 High-Speed Steel (HSS)

HSS is the hardening agent. It is a steel alloyed with tungsten, molybdenum, or chromium.

• Characteristics: It withstands high temperatures (up to 1100°F). It retains a sharp edge longer than carbon steel.

• Critical Weakness: HSS is brittle. A solid HSS reciprocating blade is unsafe. It would snap like glass under the bending forces of demolition.

3.3 Bi-Metal (BIM) Construction

Bi-Metal is the industry workhorse. It combines the flexibility of HCS with the hardness of HSS.

The Manufacturing Process:

1. A strip of hard High-Speed Steel is placed atop a flexible spring steel back.

2. An electron beam welds them together in a vacuum.

3. Teeth are ground into the hard HSS edge.

The Result: The spring steel body allows the blade to bend. The HSS edge cuts through nails and pipes. Premium blades often use Matrix II steel with 8% Cobalt. Cobalt drastically improves heat resistance, essential for cutting hard metals.

3.4 Tungsten Carbide (TCT)

Carbide is the modern standard for extreme duty. It is a ceramic-metal composite (cermet). It is significantly harder than any steel.

• Construction: Carbide teeth are individually brazed or welded onto the blade body.

• Performance: Carbide lasts up to 50 times longer than bi-metal.

• Application: It cuts what other blades cannot. Use it for cast iron, stainless steel, and high-strength alloys. It resists the abrasive wear of masonry and cement board.

3.5 Diamond Grit

Diamond is the ultimate abrasive. These blades have no teeth. Instead, industrial diamonds are bonded to the edge.

• Mechanism: They grind rather than cut.

• Application: Glass, ceramic tile, porcelain, and stone. They produce a smooth edge but cut slowly.

Material Selection Matrix

4. Tooth Geometry and Configuration

4.1 TPI (Teeth Per Inch) Strategy

TPI is the defining metric for blade selection. It controls the balance between speed and finish.

Low TPI (3-6):

• Design: Huge teeth. Massive gullets.

• Action: Aggressive gouging.

• Application: Demolition wood, tree pruning, rough lumber.

• Physics: The deep gullets eject large sawdust chips to prevent binding.

Medium TPI (8-14):

• Design: Balanced tooth size.

• Action: Controlled cutting.

• Application: "The Demolition Sweet Spot." Use for nail-embedded wood, thick pipes, and structural steel.

• Benefit: Aggressive enough for wood but fine enough to not snag on nails.

High TPI (18-24+):

• Design: Tiny teeth. Shallow gullets.

• Action: Shearing and grinding.

• Application: Thin sheet metal, conduit, tubing.

• Benefit: Produces a smooth finish and reduces vibration in thin materials.

4.2 The Rule of Three

Memorise this rule for metal cutting:

At least three teeth must be in contact with the material at all times.

The Consequence of Failure:

If fewer than three teeth engage, the material falls into the gullet. The blade "straddles" the metal. On the next stroke, the tooth slams into the edge of the metal.

Result: The tooth shears off violently. The blade is ruined instantly.

4.3 Tooth Set Patterns

The "set" is the bend of the teeth. Teeth are bent left and right to create a kerf wider than the blade body. This reduces friction.

• Raker Set: A repeating pattern of Left-Right-Straight.

  • The straight tooth (raker) acts as a cleaner. It removes the centre chip.

  • Best For: Aggressive wood cutting and thick metals.

• Wavy Set: Teeth are set in a gradual, flowing wave.

  • This distributes stress across multiple teeth.

  • Best For: Thin metals and pipes. It prevents tooth stripping.

• Variable Set: Used in variable pitch blades. It optimizes cutting across different vibration frequencies.

4.4 Rake Angle (Hook Angle)

The angle of the tooth face determines the "bite."

• Positive Rake: The tooth leans forward.

  • Action: It pulls the blade into the material.

  • Use: Fast wood cutting. It is self-feeding.

• Neutral/Negative Rake: The tooth stands straight or leans back.

  • Action: It scrapes or shears.

  • Use: Hard metals and ceramics. It prevents the brittle tip from snapping under shock loads.

5. Application-Specific Analysis: Wood

5.1 Pruning and Green Wood

Living trees are full of moisture and sap. Standard blades fail here. The wet sawdust creates a paste that clogs gullets immediately.

The Solution: Use Low TPI (3-5) pruning blades.

These often feature extra-deep gullets designed to force wet chips out of the cut.

Material Choice:

• HCS: Fine for clean branches.

• Bi-Metal: Mandatory if you are cutting near the ground. Roots often trap rocks and dirt. Bi-metal resists this abrasion.

5.2 Structural Lumber and Demolition

Demolition is unpredictable. Wood hides nails, screws, and bolts.

The Solution: Bi-Metal or Carbide-Tipped blades.

Recommendation: A 6-10 TPI blade is the perfect compromise.

• It is coarse enough to cut wood fast.

• It is fine enough to mill through a nail without snagging.

Blade Thickness: Use a thicker blade (0.050" or 0.062"). A thin blade will bend when you force it through a stud. A thick blade tracks straight.

Pro Tip: If you hit a hardened screw, stop pushing. Switch to a "metal cutting" technique. Slow the stroke. Increase pressure. Let the blade mill the screw away. Then resume speed.

5.3 Pallet Dismantling

Pallets are notorious for destroying blades. The wood is dry and hard, and the nails are often twisted spiral shank nails.

The Solution: Specialised Pallet Blades.

• Reverse Tip: Look for a blade with a rounded or "reverse" tip. This prevents the tip from snagging on the wood when you plunge it between the slats.

• Variable Pitch: A 10/14 TPI configuration handles the transition from wood to nail seamlessly.

6. Application-Specific Analysis: Metal

6.1 Thin Sheet Metal and Ductwork

The Danger: Vibration and Snagging.

Large teeth catch on the thin edge of sheet metal. This rips the metal and can jerk the saw violently.

The Solution: High TPI (18-24) Bi-Metal blades.

The wavy set pattern is essential here. It ensures a smooth transition as teeth enter and exit the thin material.

Technique:

• Keep the saw shoe firmly pressed against the sheet. This creates a solid anvil.

• Run the saw at high speed.

• Use low forward pressure. Let the teeth nibble the material.

6.2 Thick Steel (Pipe, Angle Iron, I-Beams)

The Danger: Heat.

Friction generates massive heat in thick steel. If the blade turns blue, the temper is gone.

The Solution: Medium TPI (10-14) Bi-Metal or Carbide.

A 14 TPI blade is the "Goldilocks" choice for heavy-wall pipes. It balances speed and life.

Technique:

• Slow Down: Reduce the saw speed (SPM).

• Lubricate: Cutting oil is mandatory. It reduces friction. It carries heat away. It can double-blade life.

• Rock the Saw: Do not push straight. Rock the saw up and down. This reduces the surface area of contact. It increases pressure on individual teeth for a better bite.

6.3 Cast Iron

The Danger: Brittleness and Abrasion.

Cast iron crumbles. It is extremely abrasive. It turns high-speed steel teeth into rounded nubs in seconds.

The Solution: Diamond Grit or Carbide Grit blades.

Alternatively, use specialised Carbide-Tipped blades (8 TPI).

Avoid standard bi-metal blades. They are a waste of money on cast iron.

Safety Note: Cast iron pipe is heavy and brittle. Secure it thoroughly. It can crack unpredictably during the cut.

6.4 Stainless Steel

The Danger: Work Hardening.

Stainless steel has a unique property. If you rub it without cutting, it hardens. It becomes harder than the blade.

The Solution: Carbide-Tipped blades.

Carbide is harder than work-hardened stainless.

Technique:

• Heavy Feed Pressure: You must force the teeth to bite. Do not let them skate.

• Slow Speed: Keep the heat low.

• Continuous Cut: Do not stop in the middle of a cut. The metal will harden as it cools.

Metal Blade Selection Guide

7. Application-Specific Analysis: Masonry

7.1 Aerated Concrete and Brick

Masonry is sandpaper. It abrades steel instantly.

The Solution: Tungsten Carbide Tipped (TCT) blades.

Look for blades with very low TPI (2-3 TPI).

Design: These blades often have a very wide body (up to 2 inches). This width helps keep the cut straight through thick blocks.

Johnson Tools Solution: (https://www.johnsontoolscn.com/) produces specialised carbide blades engineered to withstand the abrasive matrix of aerated concrete blocks.

7.2 Ceramic and Glass

The Solution: Diamond Grit blades.

These blades grind a fine line.

Technique:

• Water Coolant: Use water to lubricate and cool the cut. This prevents thermal shock that cracks glass.

• High Speed: Run the saw fast.

• Light Pressure: Let the diamonds do the work.

8. Coatings and Surface Treatments

A blade is not just steel. It is a system. Coatings enhance performance significantly.

8.1 Paint and Lacquer

Most blades are painted.

Function: Corrosion resistance during storage.

Reality: The paint rubs off in the first cut. It offers no performance benefit.

8.2 Black Oxide

Appearance: Matte Black.

Function: It creates a porous surface. This holds lubrication oil. It aids in cooling and prevents rust.

Best For: Metal cutting applications.

8.3 Titanium Nitride (TiN)

Appearance: Gold.

Function: It is a ceramic coating. It increases surface hardness. It reduces friction significantly.

Benefit: It prevents chips from welding to the blade (galling). It extends life in high-production metal cutting.

Insight: A TiN coating on a cheap carbon steel blade is useless. Johnson Tools ensures premium coatings are applied only to high-grade alloy substrates.

8.4 Teflon / Non-Stick

Appearance: Black or Grey.

Function: It reduces friction.

Benefit: It prevents sap and pitch from sticking.

Best For: Pruning and cutting wet lumber.

9. Advanced Brand Analysis: Johnson Tools

In the global market, Johnson Tools is a manufacturing powerhouse. They are not just a brand; they are a solution provider.

9.1 Manufacturing Excellence

Johnson Tools leverages over 20 years of expertise. They utilise laser welding technology. This ensures the bond between the HSS cutting edge and the backing steel is perfect. A weak weld leads to catastrophic blade failure. Johnson Tools guarantees structural integrity.

9.2 The Product Ecosystem

Their portfolio covers every professional need:

• Bi-Metal Series: For the general contractor. Tough, flexible, and reliable.

• Carbide Series: For the industrial specialist. Cutting cast iron and stainless steel.

• Diamond & Grit Series: For the mason. Precision cutting in stone and tile.

9.3 OEM/ODM Customisation

This is a critical differentiator. Johnson Tools offers full OEM/ODM services.

Retailers can specify:

• Blade Length.

• TPI Configurations.

• Paint and Branding.

• Packaging.

This allows hardware brands to launch high-quality product lines with confidence.

Connect with Johnson Tools:

• Website: https://www.johnsontoolscn.com/

• Contact Page: https://www.johnsontoolscn.com/contact.html

• Email: Sales@Johnsontoolscn.com

10. Advanced Cutting Techniques

10.1 The Plunge Cut

You need to cut a hole in the middle of a wall. You have no drill.

The Technique:

1. Use a blade with a tapered tip.

2. Rest the shoe on the wall. Tilt the saw so the blade is not touching.

3. Start the saw at full speed.

4. Slowly tilt the saw forward. Use the shoe as a pivot.

5. Let the tip eat its way into the wall.

Warning: Hold the saw tight. Kickback is likely if the blade catches.

10.2 Flush Cutting

You need to trim a pipe flush with the floor.

The Technique:

1. Use a flexible Bi-Metal blade.

2. Insert the blade upside down (teeth facing up).

3. Bend the blade so it runs flat along the floor.

4. Cut the pipe.

Note: Ensure the blade is long enough. If the tip pulls back into the pipe during the stroke, it will catch. This causes violent kickback.

10.3 Speed Control (SPM)

Not all materials require full speed.

• Wood: High Speed (Maximum SPM). Use orbital action if available.

• Metal: Medium/Low Speed. Turn off orbital action.

• Plastics: Low Speed. High speed melts the plastic. The molten plastic welds back together behind the blade.

11. Maintenance and Troubleshooting

11.1 Cleaning Pitch and Resin

Pine resin is the enemy. It builds up on teeth. It causes friction and overheating.

Cleaning:

• Do not use oven cleaner. It damages carbide brazing.

• Do use laundry detergent mixed with water. Soak the blade.

• Scrub with a nylon or brass brush.

• Avoid steel brushes. They dull the sharp edge.

11.2 Preventing Bent Blades

Why do blades bend instantly?

• Cause 1: The tip hits the material before the saw is at speed.

• Cause 2: The blade is too long. It "whips."

• Prevention: Always press the shoe firmly against the work. Enter the cut gently.

11.3 Extending Blade Life

Use the Adjustable Shoe.

Teeth usually wear out near the base first. The rest of the blade is new.

The Trick: Extend the adjustable shoe. This forces the saw to use the fresh teeth in the middle of the blade. You essentially get two blades for the price of one.

Troubleshooting Guide

12. Safety Protocols

Respect the tool. A reciprocating saw is powerful and aggressive.

• Kickback: This happens when the blade binds. The saw bucks back at the operator.

  • Prevention: Secure the workpiece. Never cut loose branches or pipes without clamping.

• Electrical Safety: You are often cutting into walls.

  • Rule: Always check for live wires behind drywall. Use a non-contact voltage tester.

• PPE (Personal Protective Equipment):

  • Eyes: Safety glasses are non-negotiable. Chips fly at high velocity.

  • Ears: These saws are loud (100+ dB). Wear ear protection.

  • Lungs: Demolition dust is toxic. Wear a respirator, especially with masonry.

13. Conclusion

Blade selection is not guesswork. It is physics.

• For Wood: You want Aggression. Use Low TPI. Use deep gullets.

• For Metal: You want Durability. Use High TPI. Use Bi-Metal. Use Oil.

• For Masonry: You want Abrasion. Use Carbide. Use Grit.

The difference between a frustrating job and a profitable job is often the blade. Johnson Tools understands this engineering. They provide the professional grade solutions that contractors rely on.

Don't settle for generic blades. Choose the right tool for the mission.

Upgrade your cutting efficiency today. Visit (https://www.johnsontoolscn.com/) for world-class reciprocating saw solutions.