Cutting Tools Reference Library · Technical Reference

Jobber Length Drills

Jobber length is the general-purpose straight-shank twist drill series and the default when a customer asks for "a drill" without naming a series. This sheet covers when to choose it and when a shorter or longer series is the better fit.

Ref CT-0002ANSI B94.11MISO 235DIN 338

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

A jobber length drill is a straight-shank twist drill with the standard flute and overall length for its diameter. In North America the series is defined in ANSI B94.11M. The closest metric series is DIN 338, which follows the ISO 235 jobber dimensions. Jobbers are sold in fractional, number, letter and metric sizes, singly, in packs and in index sets.

How to identify

A jobber looks like an "ordinary" drill. The flutes run most of the body and the shank is the same diameter as the cutting size. It is clearly longer than a mechanics or screw machine drill of the same size and clearly shorter than a taper length drill. Packaging and catalog numbers usually say "jobber" or "JL." When in doubt, compare the overall length to the series table in ANSI B94.11M or the maker's catalog.

Common options within the series

AttributeTypical choicesNotes
Tool materialHSS, cobalt (M35, M42), solid carbideCobalt for stainless and harder steels; carbide mainly for rigid CNC setups
Point angle118°, 135°135° is usually split point for self-centering
Point styleConventional, split pointSplit point reduces walking without a center punch
FinishBright, black oxide, steam oxide, TiN, TiAlNFinish is a filter, not a separate product line
ShankRound, with or without flats, 3-flatFlats help in three-jaw chucks under high torque
FluteStandard helix, fast spiral, slow spiralFast spiral for soft, gummy metals; slow spiral for brass and plastics
Size systemsFraction, number, letter, metricSee the drill size chart for decimal equivalents

Key points

  • Jobbers are the right default for drill presses and general shop work where reach is not a problem.
  • For portable drills and cordless tools, a mechanics length drill breaks less often and walks less.
  • If the hole is deeper than the jobber's flute length, step up to taper length or an extension drill rather than drilling past the flutes. Chips cannot clear once the flutes are buried.
  • Exact flute length and overall length for each diameter come from ANSI B94.11M or the maker's catalog. Check them when a customer has a reach or clearance limit.
  • DIN 338 lengths are close to, but not identical with, ANSI jobber lengths.

Common mistakes

  • Stocking jobbers only and sending them for every job, including thin sheet and tight-clearance work.
  • Treating "black oxide jobber" and "TiN jobber" as different categories instead of finish filters on one series.
  • Assuming a metric DIN 338 drill and an inch jobber of similar size have the same length.
  • Drilling deeper than the flute length and blaming the drill when it packs and breaks.

Governing standards: ANSI B94.11M (twist drills); ISO 235 and DIN 338 (metric jobber series). Manufacturer catalogs for exact lengths.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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