Guhring 9008780317500 Spiral Point Tap 1-1/4-7 Unc

Product Description

The GUHRING 9008780317500 is a spiral point tap designed for through-hole threading in steel and similar ferrous materials. Built to Series 878 specifications, this tap features a plug chamfer and a 4-flute spiral point geometry that pushes chips ahead of the cutting edge, keeping the flutes clear during production tapping. It is manufactured from cobalt high-speed steel for improved heat and wear resistance compared to standard HSS tooling. The bright finish reduces friction and helps with chip evacuation. With a 1-1/4-7 UNC thread form, H7/H8 thread limit, and a Class 2B fit tolerance, it produces threads suitable for general mechanical fastening applications.

This tap is used in through-hole tapping operations on steel workpieces where a 1-1/4-7 UNC thread is required. The spiral point design makes it well suited for CNC machining centers, drill presses, and manual tapping where the through-hole allows chips to exit cleanly from the bottom of the bore. It is a right-hand tap intended for standard right-hand thread production. Machinists, tool and die makers, and maintenance technicians working in industrial fabrication or repair environments are the typical end users for a tap of this size and specification.

Key Features

• 1-1/4-7 UNC thread form with Class 2B fit tolerance for standard mechanical assemblies
• Cobalt high-speed steel construction provides elevated heat and wear resistance for tapping harder steels
• Spiral point geometry pushes chips forward through the hole, reducing clogging in through-hole applications
• Plug chamfer (approximately 3-5 thread lead) for easy thread starting
• H7/H8 thread limit ensures consistent thread geometry within tight tolerance bands
• Bright finish reduces surface friction and aids chip flow without a coating that could affect thread dimensions
• Right-hand cut, no coolant-through requirement, suitable for flooded or manual lubrication setups

Compatibility

Designed as an OEM-style replacement or production spiral point tap for through-hole threading operations requiring a 1-1/4-7 UNC, Class 2B thread in steel or similar materials. Compatible with standard tap holders and tapping chucks sized for a 22 mm shank diameter.

Installation Notes

This tap should be installed by a qualified machinist or toolroom technician using a tap holder or tapping chuck appropriate for the 22 mm shank and 18 mm square drive. Ensure the workpiece is securely fixtured and the spindle is properly aligned before beginning the tapping cycle to prevent tap breakage. Apply appropriate cutting fluid or tapping oil rated for the workpiece material before and during the operation. Inspect threads with a GO/NO-GO gauge after tapping to verify the 2B fit tolerance is maintained.