Hertel 88555990 Cobalt Drill Bit Wire 12 135 Pt 1/4-28

Product Description

The HERTEL 88555990 is a cobalt, short-type threaded shank drill bit designed for drilling into high-tensile strength metals. Built to wire gauge size 12, the bit measures 0.1890 inches in diameter with a 135-degree split point for fast, accurate starts without center-punching. The 1/4-28 threaded shank secures the bit firmly in compatible threaded chucks or quick-change holders used in production and maintenance drilling applications. An oxide coating adds surface hardness and mild corrosion resistance. The tapered web and web-thinned geometry reduce thrust during entry, making this bit a dependable choice for ferrous and hard alloy materials. Installed by machinists, maintenance technicians, and aerospace fabricators working with tough base metals.

This bit fits short-reach drilling tasks where minimal stick-out and rigid chuck engagement are required. The 9/16-inch flute length and 1.25-inch overall length make it suited for shallow, precise holes in tight clearance zones. It is spec-rated under NAS 965 Type D, a specification commonly referenced in aerospace and defense manufacturing environments. Right-hand cutting with a regular spiral flute provides consistent chip evacuation in ferrous metals, stainless, and high-tensile alloys. Suitable for use in drill presses, CNC machines, and hand-held drilling equipment fitted with 1/4-28 threaded chuck adapters.

Key Features

• Cobalt construction with oxide coating for durability in high-tensile metal drilling
• 135-degree split point reduces walking and lowers entry thrust
• Web-thinned, tapered web geometry for reduced drilling resistance
• 1/4-28 threaded shank for positive, repeatable chuck engagement
• NAS 965 Type D specification compliance for aerospace-grade applications
• Right-hand cut with regular spiral flute for efficient chip removal

Compatibility

Designed for use with 1/4-28 threaded chuck systems and quick-change drill holders that accept NAS 965 Type D short cobalt drill bits in wire size 12.

Installation Notes

Installation and use should be performed by qualified machinists or maintenance technicians familiar with metal-cutting tooling. Ensure the threaded shank is fully seated and torqued into the chuck before operation to prevent bit pull-out under load. Always secure the workpiece and wear appropriate PPE including eye protection when operating drill equipment. Do not exceed the recommended speed and feed rates for the base material being drilled.