Osg 1400105305 Thread Forming Tap 4-40 Unc Cobalt Tin

Product Description

The OSG 1400105305 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming 4-40 UNC internal threads without cutting or producing chips. Built from cobalt high-speed steel and finished with a titanium nitride (TiN) coating, this tap handles demanding threading applications where tool life and surface finish matter. The modified bottoming chamfer with 2 to 2.5 chamfered threads allows threading close to the bottom of blind holes. Overall length is 1.875 inches with a tapping depth of 0.559 inches. Shank diameter is 0.141 inches. Right-hand thread direction. Class of fit is 3B with a thread limit of H3. Typically installed by machinists, toolmakers, and maintenance technicians working in precision fabrication environments.

This tap is suited for blind hole threading operations in a range of metallic workpiece materials. It is rated for use in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel, making it a versatile choice for general machining, toolroom work, and production threading in small-diameter 4-40 UNC applications. The thread forming process displaces material rather than cutting it, which produces stronger threads and eliminates chip-breaking concerns in blind holes.

Key Features

• Thread forming design displaces material rather than cutting, producing chip-free blind hole threads
• Cobalt high-speed steel construction provides heat and wear resistance in tough alloys and hardened steels
• TiN coating reduces friction and extends tool life across a broad range of workpiece materials
• Modified bottoming chamfer (2 to 2.5 threads) allows threading close to blind hole bottoms
• H3 thread limit and 3B class of fit for consistent, accurate thread production
• Right-hand, 40 threads per inch, 4-40 UNC specification

Compatibility

Designed for blind hole threading in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel workpieces requiring 4-40 UNC internal threads. Material application codes P and N apply.

Installation Notes

Thread forming taps require a properly sized form tap drill hole, which differs from a standard cut tap drill size — consult a thread forming drill chart for the correct hole diameter before tapping. Use a tapping fluid or cutting oil appropriate for the workpiece material to reduce friction and extend tap life. Secure the workpiece and use a calibrated torque-limiting tap handle or tapping attachment to avoid over-torquing this small-diameter tap. Follow shop safety procedures and ensure the spindle or driver is aligned axially with the hole before engaging the tap.