Osg 3142303 Straight Flute Tap 4-40 Unc Bottoming Cobalt

Product Description

The OSG 3142303 is a straight flute bottoming tap designed for cutting 4-40 UNC internal threads in tight-tolerance applications. Built from cobalt high-speed steel and finished with a nitride coating, it delivers extended tool life in abrasive and work-hardening materials. With 4 flutes and a bottoming chamfer, it threads close to the bottom of blind holes where a taper or plug tap cannot reach. The H7 thread limit ensures consistent fit for close-tolerance assemblies. This tap is suited for machinists, toolmakers, and maintenance technicians working on small-diameter threaded holes in production or repair environments.

The 3142303 is particularly well matched for tapping plastic materials, as noted in its material application rating. Its compact overall length of 1.874 inches makes it practical for use in confined work areas or on small machined components. The straight flute design keeps chips moving out of the cutting zone in softer, non-stringy materials, reducing the risk of chip packing in shallow-depth holes. Right-hand thread direction is standard for conventional 4-40 UNC fastener assemblies.

Key Features

• Bottoming chamfer for threading to the base of blind holes
• Cobalt construction resists wear in abrasive and harder plastics
• Nitride coating reduces friction and extends cutting life
• H7 thread limit for close-tolerance 4-40 UNC thread production
• 4-flute straight design suited for non-stringy chip materials such as plastic
• Right-hand thread, no coolant-through required

Compatibility

Designed as a standard replacement straight flute tap for 4-40 UNC threading operations in Series 114; verify machine spindle size and collet compatibility before installation.

Installation Notes

This tap should be installed by a machinist or qualified maintenance technician familiar with tapping operations and proper speeds and feeds for cobalt tooling. Secure the workpiece fully before starting and ensure the tap is aligned perpendicular to the hole centerline to prevent breakage on this small diameter. Use an appropriate tapping fluid or cutting compound compatible with the workpiece material even when coolant-through is not in use. Inspect the tap for wear or chipping before each use, as small-diameter taps are prone to breakage under misalignment or excessive torque.