Osg 1738401 Spiral Point Tap 3/8-16 Unc Plug Hss

Product Description

The OSG 1738401 is a spiral point plug tap designed for threading 3/8-16 UNC holes in a production or job-shop environment. Built from vanadium high-speed steel (HSS-E) with a steam oxide finish, it drives chips forward ahead of the cutting zone, making it well suited for through-hole tapping operations. The plug chamfer provides a gradual lead-in over several threads, balancing torque and cutting performance across a range of ferrous materials. The H5 thread limit holds a 2B class of fit, delivering consistent dimensional accuracy for standard fastener assemblies. Right-hand cutting, 3 flutes, and no coolant-through design keep the tool straightforward to run in conventional drill press, CNC, or tapping-head setups.

This tap is rated for use in hardened steel, low-carbon steel, medium-carbon steel, and stainless steel. The steam oxide coating reduces friction and provides a degree of corrosion resistance during storage and use. It is appropriate for general industrial maintenance, production threading, and repair applications where a 3/8-16 UNC thread is required. The Series 300 designation places it within OSG standard catalog tooling. Overall length is 2.937 inches with a thread length of 0.759 inches (nominal 1-1/4 inches) and a shank diameter of 0.381 inches, fitting standard tap holders and chucks sized for 3/8 shank tooling.

Key Features

• Spiral point geometry pushes chips forward, ideal for through-hole tapping
• Vanadium HSS-E construction for improved wear resistance over standard M2 HSS
• Steam oxide finish reduces friction and protects against light corrosion
• Plug chamfer (approx. 3-5 thread lead) balances starting ease with torque load
• H5 thread limit produces consistent 2B class of fit for standard fastener applications
• Rated for hardened steel, low-carbon steel, medium-carbon steel, and stainless steel

Compatibility

Rated for use in hardened steel, low-carbon steel, medium-carbon steel, and stainless steel. Produces 3/8-16 UNC internal threads to a 2B class of fit with an H5 thread limit.

Installation Notes

Tapping should be performed by a machinist or maintenance technician familiar with cutting tool speeds, feeds, and tap alignment. Power down and secure the workpiece before tool changes. Use an appropriate tapping fluid or cutting oil for the material being threaded; dry tapping in stainless or hardened steel accelerates tool wear and risks breakage. Follow ASME B1.1 thread standards and verify hole diameter with the correct tap drill size before starting.