Hertel K008381AS Straight Flute Tap 5/16-18 Unc Bottoming Hss

Product Description

The HERTEL K008381AS is a straight flute bottoming tap designed to cut internal threads in through-holes and blind holes where full thread depth near the bottom is required. Built from high-speed steel with a bright uncoated finish, this tap produces a 5/16-18 UNC right-hand thread to a 3B class of fit with an H3 thread limit. It features four flutes for chip control in a variety of materials. At 2-23/32 inches overall length, it fits standard tap handles and machine tool holders used in general machining, maintenance, and fabrication work. Machinists, maintenance techs, and tool-and-die professionals reach for this tap when a bottoming chamfer is needed to maximize thread engagement in shallow blind holes.

This tap is suited for threading operations in ferrous and non-ferrous materials in shop, field, or maintenance environments. The 5/16-18 UNC thread form is one of the most common coarse-thread fastener sizes in industrial and mechanical applications, making this tap a standard item for MRO tooling inventories. It is appropriate for hand tapping as well as low-speed machine tapping setups where a bottoming profile is specified.

Key Features

• Bottoming chamfer allows threading to the bottom of blind holes with minimal unthreaded lead
• 5/16-18 UNC thread form, right-hand direction
• 3B class of fit with H3 thread limit for standard commercial tolerances
• Four straight flutes provide chip clearance and tool stability
• High-speed steel construction handles a broad range of workpiece materials
• Bright uncoated finish - no added coating layer to affect tolerance buildup

Compatibility

Designed as an OEM-style replacement or standard tooling addition for 5/16-18 UNC threading applications. Fits standard square-drive tap handles and tap chucks sized for this shank diameter.

Installation Notes

Use cutting fluid appropriate for the workpiece material to extend tool life and improve thread finish. Secure the workpiece fully before tapping to prevent movement under torque. For hand tapping, use a tap wrench and advance the tap with periodic back-turns to break chips. For machine tapping, verify spindle speed is set for the material and tap size per standard speeds-and-feeds references before engaging the tap.