Osg 1400128100 Thread Forming Tap 1/4-28 Unf Bottoming Cobalt

Product Description

The OSG 1400128100 is a thread forming tap in the HY-PRO NRT series, designed for cold-form threading in blind hole applications. Manufactured from cobalt with a bright finish, it produces 1/4-28 UNF right-hand internal threads without cutting - displacing material rather than removing chips, which results in stronger thread form and less risk of chip packing in blind holes. The bottoming chamfer (1 to 1.5 threads) allows threading close to the bottom of a hole. Overall length is 2.5 inches with a thread length of 0.594 inches and a tapping depth of 0.933 inches. A licensed machinist or toolroom technician installs this tap in CNC, turret, or hand-tapping setups.

This tap is rated for use in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. It is best suited for blind hole threading where chip evacuation is a concern and thread strength is critical. The H7 thread limit provides a standard tolerance class appropriate for most commercial and precision threading applications in these materials. No coolant-through capability is present, so flood or mist coolant applied externally at the tap entry is the recommended approach when running at speed.

Key Features

• Thread forming (chipless) design eliminates chip packing in blind holes
• Cobalt construction for heat resistance and durability in tough materials including hardened steel and stainless steel
• Bottoming chamfer (1 to 1.5P) enables threading close to hole bottom
• H7 thread limit for standard commercial tolerance class on 1/4-28 UNF threads
• Right-hand thread direction, compatible with standard tapping heads and CNC rigid tap cycles
• Bright finish - no coating to flake or chip during forming operations

Compatibility

Designed for blind hole thread forming in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel workpieces. Material application codes P and N confirm suitability across ferrous and non-ferrous material groups as defined in the input specifications.

Installation Notes

Thread forming taps require a larger pilot hole diameter than cutting taps - consult an NRT forming tap drill chart for the correct pre-drill size before use. Secure the workpiece and ensure the tap is aligned perpendicular to the hole to avoid thread distortion or tap breakage. Use a tapping fluid or cutting oil appropriate for the workpiece material; for stainless steel and hardened steel, a sulfurized or chlorinated cutting fluid is typically recommended. Power down or disengage the tapping head before measuring thread depth.