Why Shank Type Matters
The shank is the non-cutting end of a drill bit — the part that fits into your drill chuck or machine spindle. Choosing the wrong shank type means the bit either will not fit your equipment or will not deliver the torque and rigidity needed for accurate drilling.
Three shank types dominate the HSS drill bit market: straight shank, taper shank, and reduced shank. Each is designed for specific machines and applications.
Straight Shank (Cylindrical)
The most common shank type worldwide. The shank diameter equals the drill diameter, and the bit is held in a standard three-jaw chuck.
Standards
DIN 338 — Standard length, the most popular specification globally
DIN 340 — Long series, for deeper holes
ASME B94.11M — North American jobber length equivalent
Best For
Handheld drills — Cordless and corded power drills with keyless or keyed chucks
Drill presses — Light to medium-duty bench and floor drill presses
CNC machines — When held in collet chucks or drill chucks
Diameter range — Typically 0.5mm to 16mm (above 16mm, reduced shank is more practical)
Advantages
Universal compatibility with any three-jaw chuck
Easy to re-sharpen without affecting the shank
Available in the widest range of sizes and grades
Taper Shank (Morse Taper)
Taper shank drill bits use a Morse taper (MT) that fits directly into the machine spindle without a chuck. The taper provides a self-locking friction fit that transmits high torque without slipping.
Morse Taper Sizes
MT1 — Drill diameters roughly 3–14mm
MT2 — Drill diameters roughly 14–23mm
MT3 — Drill diameters roughly 23–32mm
MT4 — Drill diameters roughly 32–50mm
MT5 — Drill diameters above 50mm
Standards
DIN 345 — The primary European standard for taper shank drills
ASME B94.11M — North American equivalent
Best For
Drill presses and milling machines — Where the spindle accepts Morse tapers directly
Large diameter drilling — 14mm and above, where chuck grip becomes unreliable
Heavy-duty production — Maximum rigidity and torque transfer
Advantages
No chuck needed — direct spindle mounting
Superior torque transmission for large diameters
Self-centering for better hole accuracy
Quick tool changes with a drift key
Reduced Shank (Silver & Deming)
Reduced shank drill bits have a cutting diameter larger than the shank diameter. The most common configuration is a 1/2" (12.7mm) shank with cutting diameters from 9/16" to 1" or larger.
Best For
Drilling large holes with standard chucks — Use a 1/2" chuck to drill holes up to 1" or larger
Portable drilling — When you need large holes but only have a handheld drill
Maintenance and field work — One chuck size handles a wide range of hole diameters
Advantages
Drill large holes without needing a taper shank machine
Compatible with standard 1/2" and 13mm chucks
Available with 135° split point for accurate starting
Limitations
Lower torque capacity than taper shank — the reduced shank is the weak point
Not ideal for production drilling of hard materials at large diameters
Quick Selection Guide
Handheld drill, general shop work, up to 13mm — Straight shank
Drill press or milling machine, 14mm and above — Taper shank
Large holes with a standard 1/2" chuck — Reduced shank
CNC machines — Straight shank in collet chucks for small diameters, taper shank adapters for large