Hertel K033011AS Spiral Flute Tap 1/4-20 Unc Bottoming Hss

Product Description

The HERTEL K033011AS is a spiral flute bottoming tap designed to cut internal threads in blind holes where thread depth must extend close to the bottom. Built from high-speed steel with an oxide coating, this tap handles the demands of production and maintenance threading operations. The spiral flute design pulls chips up and out of the hole, reducing clogging and improving thread quality in ductile materials. Key specs include a 1/4-20 UNC thread form, H3 thread limit, 3B class of fit, and a 45-degree helix angle — all matched for precision threading in steel, aluminum, and similar materials.

This tap is suited for use in machine shops, maintenance facilities, and general manufacturing environments. The bottoming chamfer — typically 1 to 2 thread leads — allows threading to the bottom of blind holes, making it the right choice when a plug or taper tap cannot provide sufficient thread engagement in the available depth. A licensed machinist or tool-and-die technician typically handles this type of operation, though skilled maintenance techs regularly use bottoming taps for in-field thread repair work.

Key Features

• Bottoming chamfer for threading blind holes to maximum depth
• 45-degree right-hand helix flute promotes chip evacuation in ductile metals
• H3 thread limit ensures consistent fit within 3B class of fit tolerance
• High-speed steel construction provides wear resistance across common work materials
• Oxide coating reduces friction and provides light corrosion resistance during storage
• Right-hand thread direction, compatible with standard tap holders and tapping heads

Compatibility

Designed as an OEM-style replacement or standard production tap for 1/4-20 UNC threading applications requiring a bottoming chamfer and 3B class of fit tolerance.

Installation Notes

Secure the workpiece firmly before tapping and ensure the pilot hole is drilled to the correct tap drill diameter for 1/4-20 UNC thread form. Use a suitable tapping fluid or cutting oil to extend tap life and improve thread finish. Back the tap out periodically to break and clear chips, particularly in deep blind holes. Follow applicable shop safety standards and machine guarding requirements when operating in a powered tapping setup.