Hertel K008304AS Straight Flute Tap 12-28 Unf Hss

Product Description

The HERTEL K008304AS is a straight flute tap designed for cutting 12-28 UNF internal threads in a range of workpiece materials. Built from high-speed steel with a bright, uncoated finish, it features 4 straight flutes and a taper chamfer that guides the tap smoothly into the hole at the start of the cut. The taper chamfer distributes cutting load across several leading threads, reducing entry torque and the risk of tap breakage. Overall length is 2.375 inches. This tap is suited for machinists, tool-and-die technicians, and maintenance professionals working with threaded fastener holes in steel, cast iron, aluminum, and similar materials.

The K008304AS is used in manual tapping operations with a tap wrench, as well as in low-speed machine tapping on drill presses or CNC machines where a floating tap holder is used. The taper chamfer style makes it a preferred choice for through-holes or when starting a thread from scratch in a blind hole where full thread depth is not required immediately. Class of fit 2B and 3B coverage provides versatility across standard UNF fastener applications in both general assembly and precision maintenance work.

Key Features

• 12-28 UNF thread form for fine-pitch unified national thread applications
• 4 straight flutes suited for short-chipping materials such as cast iron, aluminum, and mild steel
• Taper chamfer distributes cutting load over 7 to 10 leading threads for controlled thread entry
• High-speed steel construction provides toughness and wear resistance in general-purpose tapping
• Bright, uncoated finish allows direct inspection of cutting edge condition
• Right-hand thread direction, H3 thread limit for consistent fit across 2B and 3B tolerance classes

Compatibility

Designed for cutting 12-28 UNF internal threads and compatible with standard tap wrenches, T-handle tap holders, and floating tap holders sized for the corresponding tap shank. Covers class of fit 2B and 3B per UNF thread standards.

Installation Notes

This tap is installed and used by machinists and maintenance technicians following standard tapping procedures. Secure the workpiece before starting, use the correct tap drill size for 12-28 UNF to achieve the required thread engagement, and apply cutting fluid appropriate for the workpiece material to extend tap life and improve thread finish. When using in a machine, set spindle speed to the low end of the recommended range for high-speed steel taps and use a floating holder to prevent tap breakage from misalignment. Inspect cutting edges before each use and discard the tap if chipped or worn to avoid thread quality issues.