Osg 1720101 Spiral Flute Tap 3/8-16 Unc Modified Bottoming

Product Description

The OSG 1720101 is a spiral flute tap designed for threading 3/8-16 UNC internal threads in difficult-to-machine materials. The spiral flute geometry pulls chips up and out of the hole during the tapping cycle, making it well-suited for blind-hole applications where chip evacuation is critical. This tap features a modified bottoming chamfer, which provides a short lead for threading close to the bottom of a blind hole while still offering enough guidance for accurate thread starting. It is manufactured from powdered metal and finished with a steam oxide coating to reduce friction and extend tool life in demanding materials. Licensed machinists and tool and die makers are the primary users.

The OSG 1720101 is intended for tapping stainless steel, hardened steel, titanium, and high-nickel alloys — materials that work-harden quickly and demand a tap geometry that minimizes heat buildup and torque. It is commonly used in production machining, maintenance and repair operations, and precision fabrication environments where 3B class-of-fit threads are required. The right-hand spiral flute and right-hand thread direction suit standard CNC or manual tapping operations. Coolant-through capability is not present on this tap.

Key Features

• Modified bottoming chamfer allows threading within close proximity to the bottom of a blind hole
• Spiral flute design evacuates chips upward, reducing the risk of chip packing in blind holes
• H3 thread limit maintains consistent 3B class-of-fit tolerances across a production run
• Powdered metal construction provides wear resistance in tough materials including stainless steel, titanium, and high-nickel alloys
• Steam oxide coating reduces friction and helps resist built-up edge on the cutting faces
• 10-degree helix angle balances chip flow with cutting stability in the target material group

Compatibility

Designed for cutting 3/8-16 UNC right-hand internal threads in stainless steel, hardened steel, titanium, and high-nickel alloy workpieces where a 3B class of fit is specified.

Installation Notes

This tap should be installed in a tapping chuck or rigid tap holder appropriate for the machine spindle in use. Ensure the workpiece is securely fixtured and the tap is properly aligned to the drilled hole before beginning the tapping cycle. Apply a cutting fluid rated for the workpiece material, particularly when working with stainless steel or titanium, to manage heat and prevent galling. Inspect the tap for wear or chipping before each use and replace it at the first sign of torque increase or surface finish degradation in the thread.