Buy Long Drill Bits Online in Australia
Long Drill Bit Sizes — Quick Reference
Long series and extra-long drill bits extend flute and overall length beyond the standard jobber drill — for drilling deeper holes, reaching past workholding obstruction, or accessing through thick sections. Match drill TYPE to substrate (HSS for mild steel, cobalt for stainless/tough alloys) and LENGTH to your reach requirement. AIMS stocks Sutton Tools, P&N and NACHI long-series drills.
| Drill Length Series | Overall Length (Typical) | Flute Length | Best For |
|---|---|---|---|
| Jobber (Standard) | ~12-14× drill diameter | ~9× diameter | General drilling — workshop default |
| Stub Series (Short) | ~6-8× diameter | ~4× diameter | Stiffer drill, less flex — sheet metal, light work |
| Long Series | ~17-20× diameter | ~12-14× diameter | Deeper drilling, past workholding, thicker plate |
| Extra-Long | ~24-30× diameter | ~18× diameter | Very deep holes, hard-access positions |
| Aircraft Extension | 150-300 mm long | ~80% of overall | Aviation, automotive panel work, deep-reach repair |
Important: longer drills are MORE FLEXIBLE and prone to wandering. Use a starter drill, pilot hole, or drill bushing for accurate hole position when using long drills. Run at LOWER RPM than equivalent jobber drills to compensate for vibration. For cobalt drilling on stainless/tough alloys, see cobalt drill bits. For drill bit sizing reference, see our drill bit size chart. Companion ranges: drilling, jobber drill bits.
Long Drill Bits for Deep Hole Drilling
Long series and extra-long drill bits are designed for drilling deeper than standard jobber-length drills allow — reaching through thick sections of material, drilling at depth in blind holes, or accessing drilling positions that standard-length drills cannot reach due to interference with the work surface or workholding. AIMS Industrial stocks long series HSS and cobalt drill bits from Sutton Tools, P&N, and NACHI for engineering workshops, toolrooms, and maintenance operations requiring extended drilling reach.
Long Series vs Extra-Long Drill Bits
Long series drills extend the flute length and overall length beyond the jobber series standard, providing greater reach while retaining the same shank diameter and point geometry. They are the practical choice for most extended-reach drilling applications — drilling through heavy plate, elongated tube sections, or parts where the drill needs to reach past obstruction before entering the material. Extra-long drills provide even greater extension for applications requiring significant depth, such as drilling through structural members, machine frames, or extended component lengths. As flute length increases, lateral rigidity decreases — extra-long drills require careful support, reduced feed rates, and more frequent withdrawal for chip clearing to avoid deflection and drill breakage.
Sutton Tools Long Series Drills
Sutton Tools manufactures long series HSS drills to precise dimensional standards that provide consistent diameter accuracy and surface finish over the extended flute length. Sutton's Australian manufacturing heritage and engineering commitment make their long series range a reliable production drill for workshop and toolroom applications. The M35 cobalt variant provides improved heat resistance for drilling in stainless steel and high-tensile alloys where the extended contact time of deep drilling generates significant heat at the cutting edge.
P&N and NACHI Long Drills
P&N long series drills offer competitive performance for general workshop deep drilling in mild steel, aluminium, and engineering plastics. NACHI, a Japanese manufacturer with a strong reputation in precision cutting tools, produces long series drills with tight tolerances and consistent geometry — well suited to toolroom and precision component applications where hole position accuracy over depth is important. NACHI cobalt-grade long drills are specified for demanding materials where standard HSS would lose cutting edge integrity before reaching the required depth.
Drilling Technique for Long Bits
Successful deep drilling with long series bits requires attention to several factors: correct starting speed for the material and drill diameter, adequate coolant or cutting fluid delivery to the drill tip, frequent withdrawal to clear chips before they compact in the flute and cause breakage, and proper workholding to prevent component movement that would side-load the drill. For drill selection by material type, size, and depth requirements, or for bulk supply pricing, contact our team at AIMS Industrial.