Osg 1978600 Straight Flute Tap M36x4 Metric Coarse 6H Hss

Product Description

The OSG 1978600 is a straight flute tap designed for cutting M36x4.00 metric coarse internal threads in a range of ferrous and non-ferrous materials. Built from high-speed steel with a bright/uncoated finish, this tap features a plug chamfer style for general-purpose through-hole and blind-hole threading applications. It carries a 6H class of fit and a D9 thread limit, ensuring consistent tolerance control for standard metric fastener engagement. With 4 flutes and a 3-inch thread length, it is suited for production tapping on manual or CNC equipment where chip evacuation from straight flutes is acceptable. Machinists and tooling technicians working in job shops, maintenance facilities, and manufacturing operations are the primary users.

This tap is designed for use on aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The plug chamfer distributes cutting load across the leading threads, making it effective for both through-holes and deeper blind holes where partial thread starts are acceptable. At M36 diameter, this tool is typically applied in heavy-equipment fabrication, structural metalwork, and large-component maintenance scenarios where large-diameter threaded connections are required.

Key Features

• M36x4.00 metric coarse thread form with 6H class of fit for standard tolerance metric threading
• D9 thread limit for controlled oversize fit allowance
• 4-flute straight flute geometry suitable for short-chipping materials including cast iron and aluminum
• Plug chamfer distributes cutting forces across multiple lead threads
• High-speed steel construction provides toughness across a broad range of workpiece materials
• Bright/uncoated finish — no coating buildup to affect thread dimensions
• No coolant-through requirement; compatible with flood or manual lubrication setups

Compatibility

Designed for cutting M36x4.00 metric coarse threads per standard 6H tolerance in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces. Part of OSG Series 141.

Installation Notes

Secure the tap in a proper tap holder or CNC tapping chuck rated for the torque demands of M36 threading before beginning the operation. Ensure the workpiece is firmly fixtured and the pilot hole is drilled to the correct diameter for M36x4.00 metric coarse thread engagement. Apply appropriate cutting fluid or tapping lubricant for the specific workpiece material throughout the operation. Do not exceed the torque capacity of the holder or attempt to back-tap without reversing the spindle to avoid tool breakage in large-diameter applications.