Spiral Point Tap vs. Spiral Flute Tap: What’s the Real Difference?

If you’ve ever stared at a tool catalog wondering whether to specify a spiral point​ or spiral flute​ tap, you’re not alone. The names sound similar, the applications overlap, and the wrong choice can mean broken tools, scrapped parts, and unhappy customers. Let’s break down exactly how they work, where each one shines, and how to quote them with confidence.

The Core Difference in One Sentence

A spiral point tap​ (often called a gun tap) pushes chips forward, out the bottom of the hole. A spiral flute tap​ pulls chips backward, up and out of the hole. That single design choice decides everything: which materials they handle, how fast they run, and what hole type they’re built for.

Geometry at a Glance

Spiral Point Tap (Gun Tap) — Deep Dive

The spiral point is ground into the chamfer so each cutting edge acts like a ramp. As the tap rotates, chips are forced ahead​ of the cutting action and ejected through the exit side of a through-hole.

Advantages:

• Chips never accumulate in the flutes → lower torque
• Can be run at higher RPM​ than spiral flute in the same material
• Simpler geometry → lower cost per tool
• Superior thread finish on through-holes

Data point:​ In 6061 aluminum, an M8 × 1.25 HSS-E spiral point tap typically runs at 25–35 m/min​ (Vc) with a 2–3 s/hole cycle time. Tool life often exceeds 3,000–5,000 holes​ before resharpening.

Limitation:​ In a blind hole, chips pile at the bottom with nowhere to go. The tap binds, torque spikes, and breakage follows. Spiral point taps should not​ be used in blind holes deeper than ~1×D.

Spiral Flute Tap — Deep Dive

The helical flute acts like a screw conveyor. As the tap cuts, chips are lifted upward​ and evacuated through the flutes, out of the hole mouth. This makes it the go-to choice for blind holes.

Advantages:

• Reliable chip evacuation in blind holes up to 3×D and deeper
• Can handle tougher materials (stainless, alloy steel) where chip control is critical
• Less prone to chip recutting than straight-flute taps

Data point:​ In 304 stainless, an M10 × 1.5 spiral flute tap with 35° helix typically runs at 10–15 m/min​ (Vc). Tool life ranges 300–600 holes​ per tap in production. Peck-tapping extends life by another 30–50%.

Limitation:​ Higher torque demand due to the auger effect. Needs a rigid machine and proper synchronization. Not ideal for through-holes where a spiral point would cut faster and cheaper.

Real-World Comparison: Same Part, Two Different Tools

A customer machining hydraulic manifolds​ in 4140 steel (30 HRC) had 200,000 holes/year:

• Through-hole sections (M12 × 1.75):​ Spiral point tap at 28 m/min → 2.5 s/hole. Tool life 4,200 holes. Scrap rate 0.02%.
• Blind-hole sections (same thread):​ Spiral flute 35° at 16 m/min → 4.8 s/hole. Tool life 1,100 holes. Scrap rate 0.05%.

Switching the through-holes to spiral point saved ~$4,200/year​ in cycle time alone. The blind holes stayed on spiral flute because the alternative was daily tap breaks and rework.

How to Quote the Right Tap to Your Customer

Bottom Line

The choice is simple once you know the hole: through = spiral point, blind = spiral flute.​ Using a spiral point in a blind hole is the fastest way to break a tap. Using a spiral flute in a through-hole wastes cycle time and money. Match the geometry to the part, and your threading operation will run longer, faster, and cleaner.

Need a printable tap-selection chart for your quotation pack?​ Contact our technical team—we’ll send a one-page reference covering hole type, material, and recommended tap geometry.