Spiral Flute vs Spiral Point taps

Selecting the right tap is one of the most important decisions you'll make in your workshop. The wrong choice can result in broken tools, poor thread quality, and wasted time. Two of the most common tap designs—spiral flute and spiral point (gun) taps—serve fundamentally different purposes.

This guide explains how each tap works, when to use them, and how to avoid costly mistakes. Whether you're running a CNC machine, hand tapping, or managing a maintenance department, understanding these differences will improve your results and reduce tool breakage.

What is a Spiral Flute Tap?

A spiral flute tap has helical flutes that wind around the tap body, similar to a twist drill bit. As the tap rotates and advances into the workpiece, these spiral flutes actively pull chips backward—out of the hole and toward the shank of the tap.

Think of the spiral flutes as a screw conveyor. They continuously move chips away from the cutting edge and out of the hole. This is why spiral flute taps are sometimes called "suction taps"—they literally suck chips out of the hole as they work.

The spiral design creates a lower core strength compared to straight-flute taps, but modern spiral flute taps are engineered with sufficient rigidity for most applications. The trade-off—slightly less strength for superior chip control—is well worth it in blind holes.

Advantages of Spiral Flute Taps

• Blind hole capability: The primary advantage. Chips are actively removed, preventing jamming and breakage.
• Reduced breakage: No chip packing means fewer broken tools and less downtime.
• Better thread quality: Continuous chip removal prevents thread damage and ensures clean, consistent threads.
• Versatility: Can be used in both blind and through holes, making them a safe choice when you're unsure.
• Works in tough materials: Excellent performance in stainless steel, cast iron, and other stringy materials where chip control is critical.
• Longer tool life: Less stress on the tool due to better chip evacuation.

Disadvantages of Spiral Flute Taps

• Lower core strength: Not ideal for very high-speed applications or extremely tough materials.
• Slower speeds: Generally run at moderate speeds compared to spiral point taps.
• Higher cost: More complex geometry means higher manufacturing cost.
• Less efficient in through holes: Chips are pulled backward instead of being pushed forward, which is less efficient when there's an open exit path.

What is a Spiral Point Tap?

A spiral point tap, also called a gun tap, has straight flutes with an angular cutting edge ground into the tip. This geometry is specifically designed to push chips forward—ahead of the tap as it advances through the workpiece.

The angled cutting edge forces chips to break and move in the direction of tool travel. Chips are expelled out the front of the hole and into the material ahead. This forward-chip evacuation is highly efficient when there's an open path for chips to exit.

Spiral point taps have a high core strength due to their straight-flute design. This makes them robust and capable of handling high speeds and heavy feeds in through-hole applications.

How Spiral Point Taps Work

• Straight flutes with angled cutting edge rotate and advance
• The angled tip forces chips forward (ahead of the tap)
• Chips are expelled into the material ahead of the hole
• High core strength resists deflection and breakage
• Efficient chip evacuation in through holes

Advantages of Spiral Point Taps

• High speed capability: The robust core strength allows faster speeds, improving productivity in through-hole applications.
• Excellent core strength: Resists deflection and handles heavy feeds without breaking.
• Efficient chip evacuation: Forward-chip ejection is highly efficient when there's an open exit path.
• Lower cost: Simpler geometry means lower manufacturing cost.
• Proven design: Widely used and trusted in production environments.

Disadvantages of Spiral Point Taps

• Cannot be used in blind holes: This is the critical limitation. Chips cannot exit ahead of the tap, so they accumulate in the hole.
• High breakage risk in blind holes: Chip packing creates pressure that jams the tool and causes breakage.
• Thread damage in blind holes: Accumulated chips damage the thread and create poor surface finish.
• Not versatile: Strictly for through-hole applications.

Key Differences Between Spiral Flute and Spiral Point Taps

Chip Evacuation

This is the fundamental difference. Spiral point taps push chips forward; spiral flute taps pull chips backward. In a through hole, forward evacuation is more efficient. In a blind hole, backward evacuation is essential.

Core Strength

Spiral point taps have higher core strength due to their straight-flute design. Spiral flute taps have good but slightly lower core strength. For most applications, this difference is not significant, but it matters in high-speed, heavy-feed situations.

Speed and Feed

Spiral point taps can run faster in through holes. Spiral flute taps run at moderate speeds but with superior chip control. The choice depends on your application priority: speed or reliability.

Versatility

Spiral flute taps work in both blind and through holes. Spiral point taps work only in through holes. If you need one tap for multiple applications, spiral flute is the safer choice.

Which Tap Should You Use?

Blind Hole Applications

Use: Spiral Flute Tap

Blind holes have no exit path for chips. Using a spiral point tap in a blind hole is a recipe for disaster. Chips accumulate, pressure builds, and the tap breaks. Spiral flute taps are engineered specifically for this situation. The spiral geometry actively pulls chips out, preventing jamming and breakage.

This applies to all blind-hole tapping: CNC machines, manual machines, hand tapping, and production runs. There are no exceptions.

Through Hole Applications

Use: Spiral Point Tap (for speed) or Spiral Flute Tap (for reliability)

In through holes, spiral point taps are more efficient and can run faster. If speed and productivity are your priority, use spiral point taps. If you want a more versatile tap that works in both blind and through holes, use spiral flute taps.

Many workshops use spiral flute taps for all applications simply because they're more versatile and eliminate the risk of using the wrong tap.

Stainless Steel Applications

Stainless steel is stringy and produces long, continuous chips. Spiral flute taps excel in stainless steel because they actively pull chips out. Spiral point taps can work in stainless steel through holes, but chip control is more challenging.

For blind holes in stainless steel, spiral flute taps are essential. The active chip removal prevents the long chips from jamming the hole.

Aluminium Applications

Aluminium produces short, easy-to-evacuate chips. Both tap types work well in aluminium. Spiral point taps can run faster in through holes. Spiral flute taps work reliably in blind holes.

For blind holes in aluminium, use spiral flute taps. For through holes, either tap works, but spiral point taps offer higher speed.

Common Mistakes When Selecting Taps

Using Spiral Point Taps in Blind Holes

This is the most common and costly mistake. Spiral point taps cannot evacuate chips from blind holes. The result is broken tools, wasted time, and frustration. Always use spiral flute taps in blind holes.

Not Considering Material Type

Stringy materials like stainless steel and cast iron require better chip control. Spiral flute taps are the better choice. Soft materials like aluminium are more forgiving, but spiral flute taps still work well.

Ignoring Hole Depth

Deep blind holes require excellent chip evacuation. Spiral flute taps are essential. Shallow blind holes are less critical, but spiral flute taps are still the right choice.

Assuming One Tap Fits All

Different applications require different taps. Understand your hole type, material, and speed requirements before selecting a tap.

Buying the Cheapest Option

A broken tap costs far more than the savings from buying a cheaper tap. Invest in quality taps from reputable manufacturers. The cost difference is minimal compared to the cost of downtime and rework.

Need Help Selecting the Right Tap?

True Tooling's technical team has decades of combined machining experience. We can help you select the right tap for your specific application, material, and machine. Contact us today for expert advice and product recommendations.