Osg 1400105405 Thread Forming Tap 4-40 Unc Cobalt Tin

Product Description

The OSG 1400105405 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming internal threads without chip generation. It carries a 4-40 UNC thread specification with a modified bottoming chamfer of 2 to 2.5 chamfered threads, making it suited for threading close to the bottom of a blind hole. Manufactured from cobalt high-speed steel and finished with a titanium nitride (TiN) coating, it provides elevated heat and wear resistance compared to standard HSS taps. The H4 thread limit ensures consistent thread tolerance across production runs. Licensed machinists and tool-and-die professionals install this tap in manual and CNC tapping applications.

This tap is intended for blind hole threading in a range of workpiece materials including alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The modified bottoming chamfer allows thread forming to start close to the bottom of the hole, maximizing usable thread depth. With a tapping depth of 0.559 inches and a thread length of 0.295 inches, it is sized for small-diameter, fine-pitch work common in precision machining, instrument manufacturing, and light mechanical assemblies.

Key Features

• 4-40 UNC thread specification with right-hand thread direction
• Modified bottoming chamfer (2 to 2.5 chamfered threads) for threading near blind hole bottoms
• Cobalt construction with TiN coating for extended tool life in difficult-to-machine materials
• H4 thread limit for consistent thread tolerance in production environments
• Cold-forming design eliminates chips, reducing tap breakage risk in small-diameter holes
• No coolant-through requirement — compatible with standard tapping fluids applied externally

Compatibility

Rated for use in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. Suited for blind hole threading applications requiring a 4-40 UNC thread form.

Installation Notes

This tap is installed by machinists using a tap wrench, tapping head, or CNC rigid tapping cycle set to the correct 4-40 pitch feed rate. Ensure the pilot hole diameter matches the recommended minor diameter for thread forming before starting. Apply an appropriate tapping fluid for the workpiece material to reduce friction and extend tool life. Do not reverse the tap under power without confirming the machine is configured for thread forming — chip-less forming taps require adequate torque capacity and a properly sized hole.