Osg 1135505 Hand Tap 7/8-9 Unc Tin Hss 4-flute

Product Description

The OSG 1135505 is a straight-flute hand tap designed for cutting 7/8-9 UNC internal threads in a wide range of materials. Built from high speed steel with a titanium nitride (TiN) coating, it delivers extended tool life and reduced friction during tapping operations. The plug chamfer style provides 3 to 5 chamfered threads, making it suited for through-hole and moderately deep blind-hole applications. With 4 flutes and a right-hand thread direction, this tap is driven by a tap wrench or machine and produces clean, accurate 3B-class threads to an H4 thread limit. It belongs to OSG Series 101 and is sized for demanding fastener and mechanical assembly work.

This tap is used in metalworking, maintenance, and manufacturing environments where 7/8-9 UNC threads are required. It fits residential, commercial, and industrial applications including structural fabrication, heavy equipment repair, and general machine shop work. The plug chamfer makes it the most commonly chosen starting tap when threads run through a workpiece or when a bottoming tap will follow. Licensed machinists, toolroom technicians, and maintenance tradespeople are the primary users of this tool.

Key Features

• TiN coating extends tool life and reduces built-up edge in ferrous and non-ferrous materials
• High speed steel construction withstands heat generated in hand and machine tapping
• Plug chamfer (3-5 threads) suits through-hole and general-purpose blind-hole tapping
• 4-flute straight-flute geometry provides chip clearance and stable thread form
• H4 thread limit and 3B class of fit meet standard fastener and mechanical assembly tolerances
• Right-hand thread direction compatible with standard tap wrenches and tapping heads

Compatibility

Designed for use in standard tap wrenches, T-handle wrenches, and machine tapping heads configured for 7/8-9 UNC thread cutting. Suitable as a plug tap in a three-tap set sequence or as a standalone tap for through-hole applications.

Installation Notes

Tapping should be performed by a qualified machinist or maintenance technician familiar with thread cutting procedures. Use the correct drill size for 7/8-9 UNC threads and apply appropriate cutting fluid for the workpiece material to prolong tap life and improve thread quality. Back the tap off periodically during hand tapping to break chips and prevent tap breakage. Inspect the tap for chipping or wear before each use and never force a tap that has stopped advancing.