Osg 0137901 Spiral Flute Tap 3/8-16 Unc Bottoming 3B Hss

Product Description

The OSG 0137901 is a spiral flute tap designed for cutting 3/8-16 UNC internal threads in bottoming applications. Made from vanadium high-speed steel with a steam oxide coating, this tap handles demanding threading operations in stainless steel, high-carbon steel, medium-carbon steel, and low-carbon steel. The 45-degree helix angle and three-flute spiral configuration pull chips up and out of the hole, reducing packing and improving thread quality in blind holes. The bottoming chamfer allows threads to be cut close to the bottom of a blind bore. This tool is used by machinists and maintenance technicians across metalworking, fabrication, and industrial maintenance environments.

The 0137901 is suited for blind-hole threading where a full-bottoming thread form is required. It conforms to a 3B class of fit and H3 thread limit, making it appropriate for standard-tolerance threaded assemblies. The right-hand flute direction and right-hand thread cut in the conventional direction with standard tapping equipment. At 2.938 inches overall length with a 0.5-inch thread length and 0.381-inch shank diameter, it fits standard tap holders and chucks used in manual and CNC tapping operations.

Key Features

• 45-degree spiral flute angle evacuates chips upward, ideal for blind-hole applications
• Bottoming chamfer allows threading to near the base of blind bores
• Vanadium high-speed steel construction for wear resistance in steel applications
• Steam oxide coating reduces friction and improves lubrication retention
• H3 thread limit and 3B class of fit for standard-tolerance UNC threaded holes
• Compatible material applications include stainless steel, high-carbon, medium-carbon, and low-carbon steels

Compatibility

Designed for threading 3/8-16 UNC blind holes in stainless steel, high-carbon steel, medium-carbon steel, and low-carbon steel workpieces using standard tap holders sized for a 0.381-inch shank diameter.

Installation Notes

Threading operations should be performed by a qualified machinist or maintenance technician. Always use an appropriate tapping fluid or cutting oil matched to the workpiece material, particularly when tapping stainless steel. Secure the workpiece and ensure the tap is aligned perpendicular to the hole before engagement to prevent tap breakage. When using a manual tap wrench, advance with steady forward pressure and back off periodically to break the chip.