Precision Twist Drill 5999251 No. 55 Hss Jobber Drill Bit

Product Description

The PRECISION TWIST DRILL 5999251 is a jobber-length twist drill bit sized to wire gauge No. 55 (0.0520 inches decimal), ground from high speed steel with a steam oxide coating for light corrosion resistance and reduced friction during drilling. The 118-degree standard point angle is suited for general-purpose hole-making in a wide range of workpiece materials. Overall length is 1.875 inches, flute length is 0.875 inches, and the straight-cylindrical shank matches the 0.0520-inch drill diameter. The web-thinned, tapered-web design reduces thrust load at entry. Licensed machinists, maintenance technicians, and tool-and-die tradespeople reach for this size when drilling small-diameter clearance or pilot holes.

This bit is intended for drilling operations in steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium. It fits standard drill chucks and CNC tool holders that accept a straight shank of 0.0520 inches. The regular spiral with a 17xD flute-to-diameter ratio provides adequate chip evacuation for most through-hole and blind-hole work at this small diameter. It is catalogued under Precision Twist Drill series R10, R15, and R18 and conforms to ANSI specifications for jobber-length drill geometry. Typical applications include precision metalworking, maintenance and repair operations, and light manufacturing environments.

Key Features

• Wire gauge No. 55 size — 0.0520 inches decimal diameter
• 118-degree standard point angle for general-purpose entry on ferrous and non-ferrous materials
• High speed steel construction with steam oxide coating for reduced friction and light corrosion protection
• Web-thinned, tapered web reduces axial thrust at small diameters
• 2-flute regular spiral with 17xD ratio supports chip clearance in short-hole drilling
• Straight-cylindrical shank fits standard chucks and collets without modification
• ANSI-conforming jobber-length geometry — Series R10, R15, R18

Compatibility

Designed as an ANSI-standard jobber-length drill bit for use in any drill press, hand drill, or CNC machining center equipped with a chuck or collet accepting a 0.0520-inch straight shank. No coolant-through capability; intended for dry or externally lubricated drilling only.

Installation Notes

Secure the shank fully in the chuck or collet before drilling to prevent runout at this small diameter. Use a center punch or spot drill to locate the hole and prevent walking on entry. Apply cutting fluid externally when drilling stainless steel, superalloys, or titanium to extend tool life. Inspect the cutting edges before each use — at 0.0520 inches, edge damage is not always visible without magnification.