Osg 1400137401 Thread Forming Tap 3/8-24 Unf Cobalt

Product Description

The OSG 1400137401 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming internal threads in blind holes. Unlike cutting taps, this tool displaces material rather than cutting it, producing stronger threads with no chips to clear. It is ground from cobalt high-speed steel for added hardness and heat resistance, and finished with a steam oxide coating to improve lubricity and resist galling. The 3/8-24 UNF thread profile with a modified bottoming chamfer of 2 to 2.5 threads allows threading close to the bottom of a blind hole. Class of fit is 3B with a thread limit of H5. Machinists and tool-and-die professionals specify this tap for precision threading applications in ferrous and non-ferrous materials.

This tap is suited for blind hole threading operations in production and jobshop environments. It handles a broad range of workpiece materials including alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The right-hand thread direction and standard square drive shank make it compatible with tap handles, tapping heads, and CNC rigid tapping setups. The modified bottoming chamfer is particularly useful when thread engagement must start near the bottom of a drilled hole with minimal runout allowance.

Key Features

• Thread forming design displaces material for chip-free blind hole threading and stronger thread form
• Cobalt HSS construction provides increased hardness and thermal resistance versus standard M2 HSS
• Steam oxide coating improves lubricity and reduces built-up edge in tough materials
• Modified bottoming chamfer (2 to 2.5 threads) allows threading close to hole bottom
• H5 thread limit and 3B class of fit for tight tolerance threading
• Right-hand thread, standard square drive shank for use with tap wrenches or machine tapping attachments

Compatibility

Designed for blind hole thread forming in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Part of the OSG HY-PRO NRT series 14001.

Installation Notes

Thread forming taps require a larger pilot hole diameter than cutting taps — consult the OSG HY-PRO NRT forming tap drill chart for the correct form tap drill size for 3/8-24 UNF before drilling. Apply a suitable tapping fluid or cutting oil rated for the workpiece material; this is especially important when tapping stainless or hardened steel. Secure the workpiece fully before tapping, and ensure the tap is aligned perpendicular to the hole to prevent thread distortion or tap breakage. For CNC rigid tapping, verify spindle speed and feed rate are matched to the 24 TPI pitch.