Osg 1400105100 Thread Forming Tap 4-40 Unc Bottoming

Product Description

The OSG 1400105100 is a thread forming tap designed for cold-forming internal threads without cutting, eliminating chips and reducing the risk of tap breakage in blind holes. Built from cobalt high-speed steel with a bright finish, this bottoming-style tap in the HY-PRO NRT series produces Class 2B threads to a Thread Limit of H5. The 4-40 UNC designation means 40 threads per inch on a No. 4 diameter fastener. With an overall length of 1.875 inches and a tapping depth of 0.559 inches, it is suited for tight workspaces where a standard chamfer would leave too many unformed threads near the bottom of a blind hole. Machinists and toolroom techs are the primary users.

This tap is engineered for blind hole threading applications across a broad range of workpiece materials, including alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The bottoming chamfer of 1 to 1.5 chamfered threads allows the forming action to begin as close to the bottom of a blind hole as possible. It is commonly used in precision machining, maintenance and repair operations, and production environments where chipless thread forming is preferred for strength and hole integrity.

Key Features

• Thread forming (chipless) design eliminates chip evacuation concerns in blind holes
• Cobalt HSS construction provides heat and wear resistance for tough materials including hardened steel and stainless steel
• Bottoming chamfer (1 to 1.5P) maximizes usable thread depth in blind holes
• H5 thread limit holds Class 2B fit for consistent, accurate thread geometry
• Right-hand thread direction, 4-40 UNC at 40 threads per inch
• No coolant-through requirement simplifies tooling setup

Compatibility

Designed for use in blind hole threading applications on alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Material Application Codes P and N confirm suitability for steel and non-ferrous material groups. Part of the OSG Series 14001 HY-PRO NRT line.

Installation Notes

Thread forming taps require a properly sized forming tap drill hole, which is typically larger than a standard cut tap drill size for the same thread — consult an OSG or industry forming tap drill chart for the correct pilot hole diameter before tapping. Apply a suitable tapping fluid or cutting oil rated for the workpiece material to reduce friction during the forming process. Secure the workpiece and use a calibrated tapping head or reversible drill press to maintain axial alignment and avoid galling. Do not use thread forming taps in through-hole applications where chip-clearing geometry would normally be specified.