Accupro T1634663 Spiral Flute Tap 5/8-18 Cobalt H3

Product Description

The ACCUPRO T1634663 is a spiral flute tap designed for cutting 5/8-18 UNF internal threads in a variety of workpiece materials. Built from cobalt high-speed steel with an oxide finish, this tap handles tough materials including alloy steels and stainless steel where standard HSS taps wear prematurely. The modified bottoming chamfer allows threading close to the bottom of a blind hole. Three right-hand spiral flutes with a 33-degree helix angle evacuate chips upward out of the hole, making it well suited for blind-hole tapping on manual or CNC machine tools. Licensed machinists and toolroom technicians are the primary users.

This tap applies to precision threading operations in blind holes on machined parts across manufacturing, maintenance, and repair environments. The 2 and 3B class of fit designation covers standard commercial tolerance threading used in the majority of industrial fastener and assembly applications. With an overall length of 3-13/16 inches and a thread length of 0.905 inches, it fits standard tap holders and tapping heads designed for this shank size. The H3 thread limit keeps tolerances tight for consistent fit on mating fasteners.

Key Features

• Cobalt high-speed steel construction for extended tool life in hard and abrasive materials
• Modified bottoming chamfer for threading close to the bottom of blind holes
• 33-degree right-hand spiral flutes for upward chip evacuation in blind-hole applications
• H3 thread limit for consistent 2 and 3B class of fit tolerances
• Oxide finish provides mild corrosion resistance and reduced friction during cutting
• No coolant-through requirement — compatible with flood or manual lubrication

Compatibility

Designed as an OEM-style replacement tap for standard tap holders and tapping heads accepting a 0.480-inch shank diameter, used in blind-hole tapping of 5/8-18 UNF threads.

Installation Notes

This tap is installed and operated by machinists or maintenance technicians on drill presses, milling machines, or CNC tapping centers. Always ensure the workpiece is securely fixtured and the spindle is aligned with the pre-drilled pilot hole before engaging the tap. Apply appropriate cutting fluid for the workpiece material to extend tap life and reduce the risk of breakage. Never reverse a spiral flute tap at high speed without confirming the machine is programmed for rigid tapping or a tension-compression holder is in use.