What Is A Riving Knife On A Table Saw?: Safety & Function

A riving knife on a table saw is a crucial safety feature – it’s a metal piece that sits behind the saw blade and moves up and down with it. Its main job is to prevent the wood from pinching the blade, which can cause dangerous kickback. This article delves into the riving knife’s function, importance, and how it differs from other safety devices.

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Fathoming the Riving Knife

Riving Knife Purpose: Preventing Saw Blade Binding

The riving knife’s purpose is simple but vital: prevent the wood from closing in on the spinning saw blade after it passes. When wood has internal stress, cutting it can cause the two newly separated pieces to squeeze together. This pinching action can cause the blade to bind.

Saw blade binding leads to several problems:

• Burning: Friction increases between the blade and wood.
• Stalling: The motor struggles to maintain speed.
• Kickback: The saw can violently throw the wood back towards the user.

The riving knife sits in the kerf (the slot cut by the blade) and maintains the separation, preventing these dangerous scenarios. It’s a passive device, meaning it works without the user needing to do anything extra.

Riving Knife Function: How It Works

The riving knife is mounted behind the saw blade and designed to:

• Match the Blade: It follows the arc of the saw blade.
• Adjust with Blade Height: It moves up and down with the blade.
• Stay Close: It sits very close to the blade.
• Move with Bevel: It angles with the blade when making bevel cuts.

This close proximity and dynamic movement make it effective at preventing the wood from pinching the blade throughout the cut.

What Does a Riving Knife Look Like?

A riving knife is typically a curved metal piece, usually steel, with a thickness slightly less than the saw blade’s kerf. It’s often shaped like a crescent moon or a thin fin. It is important that the riving knife is the right thickness. Too thin, and it won’t prevent binding. Too thick, and it will create friction.

Why Is A Riving Knife So Important?

Table saw accidents can cause serious injuries. The riving knife is a key part of table saw safety. It reduces the risk of:

• Kickback: The violent ejection of wood towards the operator.
• Blade Contact: By preventing erratic wood movement.

Because of its importance, modern table saws are almost always equipped with a riving knife.

Riving Knife vs. Splitter

Many older table saws use a “splitter” instead of a riving knife. While both devices serve a similar function, there are key differences.

Feature	Riving Knife	Splitter
Movement	Moves up and down with the blade; bevels with the blade	Remains stationary; may need removal for some cuts
Proximity to Blade	Very close; within a few millimeters	Can be farther away from the blade
Ease of Use	Generally easier to use and more convenient	Requires more adjustment and removal
Effectiveness	More effective due to its dynamic movement	Less effective, especially during bevel cuts

The riving knife’s ability to move with the blade is a big advantage because it stays effective throughout the cut, even when adjusting the blade height or angle. Splitters often need to be removed for non-through cuts (like dadoes), reducing their use and increasing the risk of accidents.

Anti-Kickback Device: Further Enhancing Safety

Riving knives often work together with anti-kickback pawls. These are small, toothed arms that dig into the wood if it starts to move backward during a kickback. Pawls add an extra layer of protection against kickback.

Woodworking Safety and the Riving Knife

Table Saw Safety: A Holistic Approach

The riving knife is just one piece of the table saw safety puzzle. Other important practices include:

• Using Push Sticks: Keep your hands away from the blade.
• Wearing Safety Glasses: Protect your eyes from flying debris.
• Using Hearing Protection: Table saws are loud.
• Maintaining a Safe Stance: Keep your balance and avoid reaching.
• Inspecting Wood: Check for knots, nails, or other defects.
• Keeping the Saw Clean: Sawdust buildup can be a fire hazard and affect performance.
• Never Reaching Over the Blade: Walk around the saw.

Why Remove a Riving Knife?

While a riving knife is a vital safety feature, there are certain situations where removal is necessary:

• Non-Through Cuts (Dadoes/Rabbets): When the blade doesn’t cut all the way through the wood.
• Molding Operations: When using specialized blades for shaping wood.

Important: Always replace the riving knife immediately after completing the task that required its removal.

Blade Guard Alternatives

While a riving knife is a primary safety device, blade guards offer another layer of protection. Blade guards physically cover the blade, preventing accidental contact. Many modern table saws combine a riving knife with a blade guard. Some woodworkers remove the blade guard because it can obstruct their view or interfere with certain cuts. However, removing the blade guard increases the risk of injury. If you choose to remove the blade guard, always use the riving knife.

Table Saw Accidents: Real-World Consequences

Table saw accidents can have devastating consequences, including:

• Lacerations: Deep cuts from the blade.
• Amputations: Loss of fingers or hands.
• Eye Injuries: From flying debris.

Using a riving knife correctly can dramatically reduce the risk of these types of injuries.

Avoiding Saw Blade Binding: Tips & Techniques

Beyond using a riving knife, other ways to avoid saw blade binding include:

• Selecting the Right Blade: Use a blade designed for the type of wood you’re cutting.
• Using Proper Feed Rate: Don’t force the wood through the blade.
• Managing Internal Stress: Make relief cuts in the wood before cutting.
• Using Featherboards: Keep the wood pressed against the fence.

Riving Knife Maintenance

To ensure your riving knife is working properly, it needs regular care.

How To Align A Riving Knife

Proper alignment of the riving knife is crucial for its effectiveness. Misalignment can make it useless or even dangerous. To align it:

1. Unplug the Saw: Safety first!
2. Raise the Blade: Expose enough of the blade to work with.
3. Loosen Adjustment Screws: Allows for lateral movement.
4. Align: The riving knife should be parallel to the blade and centered in the kerf.
5. Tighten Screws: Secure the riving knife in place.
6. Test: Run a test piece of wood through the saw to ensure proper function.

Regular Inspection: Catching Problems Early

Regularly inspect your riving knife for:

• Damage: Cracks, bends, or other damage.
• Alignment: Make sure it’s properly aligned.
• Cleanliness: Remove any sawdust or debris.
• Secure Attachment: Ensure it’s securely mounted.

Replace a damaged riving knife immediately.

FAQ: Riving Knives

• What is a riving knife on a table saw? A riving knife is a safety feature designed to prevent kickback by keeping the wood from pinching the blade.
• Can I use a table saw without a riving knife? While it’s possible, it’s highly discouraged. The risk of kickback and injury increases significantly.
• Who is responsible for ensuring a table saw has a riving knife? Both the manufacturer and the user share responsibility. Manufacturers are required to equip new saws with riving knives. Users are responsible for ensuring the riving knife is properly installed and used.
• Are riving knives universal? No, riving knives are typically specific to the table saw model.
• How often should I check my riving knife? Check it before each use for damage and proper alignment.
• What are blade guard alternatives? While a riving knife is a primary safety device, blade guards offer another layer of protection.
• Is there such thing as an automatic riving knife? Some high-end table saws feature automatic riving knives that retract for non-through cuts and automatically return to the working position. These are designed to increase convenience and reduce the chance of forgetting to reinstall the riving knife.

Conclusion

The riving knife is a vital safety feature on any table saw. Its simple yet effective design significantly reduces the risk of kickback and other dangerous accidents. By understanding its function, maintaining it properly, and using it in conjunction with other safety practices, you can make your woodworking safer and more enjoyable. Remember: table saw safety is paramount!