Accupro T1604162 Spiral Flute Tap 4-40 Vanadium Hss

Product Description

The ACCUPRO T1604162 is a spiral flute tap designed to cut 4-40 unified coarse internal threads in through-holes and blind holes where chip evacuation is critical. Built from 3% vanadium high-speed steel, this tap delivers increased wear resistance and edge retention compared to standard M2 HSS. The modified bottoming chamfer allows threading closer to the bottom of a blind hole while still providing enough lead to start squarely. At 1.87 inches overall length with a right-hand thread and right-hand flute direction, it fits standard tap holders and CNC tapping chucks for production or bench work alike. The H2 thread limit ensures consistent 2B and 3B class-of-fit results on standard tolerance holes.

This tap is suited for machining shops, maintenance departments, and precision assembly operations that regularly work with small-diameter 4-40 fastener applications. The modified bottoming chamfer is particularly useful in electronics enclosures, instrument panels, and mechanical assemblies where blind tapped holes are common and bottom clearance is limited. The 40-degree helix angle promotes smooth chip flow out of the hole, reducing the risk of chip packing in ductile materials such as aluminum, mild steel, and plastics. It is well suited for both manual tapping and CNC rigid tapping operations.

Key Features

• 4-40 thread size with H2 thread limit for 2B and 3B class-of-fit tolerances
• Modified bottoming chamfer for threading close to the bottom of blind holes
• 3% vanadium high-speed steel construction for superior wear resistance and edge retention
• 40-degree helix angle with fast spiral flute style for efficient chip evacuation
• Oxide finish for improved lubrication retention and corrosion resistance
• Right-hand thread and right-hand flute direction compatible with standard tap drivers

Compatibility

Designed as a direct-fit replacement tap for standard 4-40 tapping applications using H2 thread limit holders and collets. Compatible with manual tap handles, tapping heads, and CNC rigid tapping setups that accept the 3.58 mm shank diameter.

Installation Notes

Use of cutting fluid or tapping compound is strongly recommended to extend tool life and improve thread finish. Ensure the workpiece is securely fixtured before tapping to prevent tap breakage, especially at this small diameter. For CNC rigid tapping, verify spindle speed and feed rate are matched to the 4-40 pitch before engaging the tap. Always inspect the tap for chipping or wear before each use, as small-diameter taps are susceptible to breakage if dull or misaligned.