Osg 1400104900 Thread Forming Tap 4-40 Unc Bottoming Cobalt

Product Description

The OSG 1400104900 is a cobalt thread forming tap engineered for bottoming applications in blind holes. Part of the HY-PRO NRT series, it cuts 4-40 UNC right-hand threads at 40 threads per inch using a cold-forming process that displaces material rather than cutting chips, producing stronger threads with improved surface finish. The H3 thread limit and 3B class of fit make it suitable for close-tolerance fastener applications. The bright finish provides adequate lubricity for most general-purpose tapping operations. At 1.875 inches overall length and 0.295 inches of thread length, this tap is well-proportioned for small-diameter production or repair work.

This tap is designed for blind hole threading operations on a wide range of workpiece materials including alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel. The bottoming chamfer of 1 to 1.5 threads allows the tap to form threads nearly to the bottom of a blind bore, making it a practical choice for machining centers, CNC tapping, and manual tapping in tight-depth applications. Material application codes P and N confirm its suitability across ferrous and non-ferrous material groups.

Key Features

• Cobalt construction provides heat and wear resistance for tough materials including hardened steel and stainless steel
• Thread forming (chipless) design produces stronger threads and eliminates chip extraction from blind holes
• Bottoming chamfer (1 to 1.5P) enables threading close to the bottom of blind bores
• H3 thread limit with 3B class of fit for consistent, close-tolerance thread production
• Bright finish suits general-purpose tapping with standard cutting fluids
• Right-hand, 4-40 UNC configuration for standard inch-series fastener applications

Compatibility

Designed for use in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel workpieces. Suitable for blind hole tapping applications where chipless thread forming is required. Fits standard tap holders and chucks sized for a 0.141-inch shank diameter.

Installation Notes

Thread forming taps require a properly sized forming hole, which is typically larger than a standard cut-tap drill size — consult the OSG HY-PRO NRT series forming drill chart for the correct pilot hole diameter for 4-40 UNC. Use an appropriate tapping fluid or cutting oil suited to the workpiece material before engagement. Ensure the tap is driven at the recommended spindle speed for the material and diameter to avoid work hardening or tap breakage. Always secure the workpiece and use a torque-limiting tap holder when possible to protect the tap at this small diameter.