Guhring 9039310063500 Spiral Flute Tap 1/4-20 Unc

Product Description

The GUHRING 9039310063500 is a spiral flute tap designed for cutting 1/4-20 UNC internal threads in blind holes. Built from cobalt high-speed steel with a bright, uncoated finish, this tap runs a 45-degree helix angle that evacuates chips efficiently during cutting. The modified bottoming chamfer allows threading close to the bottom of a blind hole while maintaining chamfer strength. At 2.5 inches overall length, it fits standard tapping chucks and CNC rigid-tap toolholders used in production and maintenance environments. Machining professionals and toolroom technicians reach for this tap when thread quality and chip control in confined holes are the priority.

This tap is rated for use in aluminum and aluminum alloy workpieces, where its fast-flute spiral geometry and cobalt substrate perform reliably at production cutting speeds. The 2B class of fit covers the vast majority of general-purpose threaded fastener assemblies. With a thread limit of H4 and H5, it produces threads within tolerance for standard 1/4-20 UNC mating hardware. It is a solid choice for blind-hole threading operations on CNC machining centers, knee mills, or drill presses equipped with a tapping attachment.

Key Features

• 1/4-20 UNC thread form, right-hand thread, right-hand flute
• Modified bottoming chamfer for threading close to the bottom of blind holes
• 45-degree helix angle promotes upward chip evacuation in blind holes
• Cobalt high-speed steel construction for heat and wear resistance
• 2B class of fit with H4 and H5 thread limits
• Bright, uncoated finish suitable for aluminum and aluminum alloy applications

Compatibility

Designed for blind-hole threading in aluminum and aluminum alloy workpieces. Compatible with standard tapping chucks and toolholders accepting a 0.255-inch shank diameter. Rated for 1/4-20 UNC 2B thread assemblies per ASME B1.1 tolerance standards.

Installation Notes

Spiral flute taps are installed and operated by machinists and toolroom technicians. Before tapping, ensure the workpiece is securely fixtured and the spindle is aligned with the pre-drilled hole. Use appropriate tapping fluid or cutting oil for aluminum to extend tool life and maintain thread quality. When using a CNC machining center, enable rigid tapping mode and match spindle feed rate exactly to the 20 threads-per-inch pitch to avoid tap breakage.