Guhring 9055200086100 Cobalt Stub Drill Bit Size R

Product Description

The GUHRING 9055200086100 is a cobalt screw machine length (stub) drill bit designed for high-speed drilling in demanding shop environments. Built to DIN 1897 standards, it features a 118-degree four-facet split point with web thinning for fast engagement and reduced walking on entry. The drill measures 8.61 mm in diameter with an overall length of 84 mm and a flute length of 40 mm, conforming to a straight-cylindrical shank. The right-hand spiral flute geometry and tapered web configuration make it well suited for production drilling where consistent hole quality and tool life matter. Machinists and tool room technicians are the primary installers of this bit.

This bit is sized as drill size R, with a decimal equivalent range of 0.3000 to 0.3500 inches and a maximum drilling depth of 1.067 inches (27.09 mm). The stub length format keeps the bit rigid in short-reach applications, reducing deflection in screw machine and CNC drilling operations. The primary workpiece material listed is aluminum, though the cobalt construction supports use across a range of non-ferrous and ferrous materials at elevated cutting speeds. Coolant-through is not supported on this bit, so external coolant or flood coolant setups are the appropriate choice when thermal management is needed.

Key Features

• Cobalt tool material for elevated heat resistance and extended tool life
• 118-degree four-facet split point with web thinning for self-centering entry
• Stub (screw machine) length for maximum rigidity and minimal deflection
• Right-hand cut with regular spiral flute geometry
• Straight-cylindrical shank for compatibility with standard drill chucks and collets
• Manufactured to DIN 1897 specification

Compatibility

Designed as a DIN 1897 stub-length drill bit in size R, this bit fits standard drill chucks and collets accepting an 8.61 mm straight shank. It is part of GUHRING Series 5520.

Installation Notes

Installation and use of this bit should be performed by qualified machinists or tool room personnel familiar with proper chuck mounting and runout verification. Always power down and fully stop the spindle before changing bits. Verify chuck or collet grip across the full shank engagement length to prevent slippage at operating speeds. Do not exceed the maximum drilling depth of 1.067 inches for this stub-length geometry without re-evaluating setup rigidity.