Osg 1978300 Straight Flute Tap M30x3.50 Metric Coarse

Product Description

The OSG 1978300 is a straight flute plug tap designed for cutting M30x3.50 metric coarse internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel with a bright/uncoated finish, this tap delivers consistent thread quality in right-hand thread applications. It features 4 flutes, a 6H class of fit, and a D9 thread limit, making it suitable for standard-tolerance metric threading work. With an overall length of 5.4375 inches and a thread length of 2.5625 inches, the 1978300 is sized for production and repair threading in shop and field environments. Machinists and maintenance trades use this tap in manual and machine tapping operations.

This tap is intended for threading operations in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. The plug chamfer style provides a balance between ease of thread starting and thread engagement depth, making it a practical choice for through-hole and shallow blind-hole applications in both production machining and maintenance repair operations. It carries the OSG Series 141 designation.

Key Features

• M30x3.50 metric coarse thread form with right-hand direction
• Plug chamfer for balanced starting and thread engagement
• 4-flute design for chip distribution across multiple contact points
• 6H class of fit with D9 thread limit for standard metric tolerance requirements
• High-speed steel construction without coating, suitable for a broad range of workpiece materials
• No coolant-through feature — compatible with conventional flood or manual lubrication

Compatibility

Rated for use in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces. Designed as an OEM-style metric tap for standard M30x3.50 thread applications in manual tap handles, tapping heads, and CNC tapping operations.

Installation Notes

This tap should be installed and operated by qualified machinists or maintenance technicians familiar with metric threading standards. Power down or de-energize any machine spindle before mounting or removing the tap. Apply appropriate cutting fluid for the workpiece material to reduce heat and extend tap life. Follow the machine tool manufacturer's recommended RPM and feed rate for the tap diameter and material being threaded.