More different specifications are showing up in manufacturing prints in the USA. To help
clarify abbreviations see the explanations below.
- ASME/USCTI USA tool standards. American Society of
Mechanical Engineering / United States
Cutting Tool Institute, all standards are
specified in the imperial measurement
- DIN German standard. Deutsches Institut Fur
Normung / German Institute for Standard, all measurements are to the metric system.
- JIS Japanese standard. Japanese Industrial
Standard, all measurements are to the
- ISO Global standard. International Standardization
Organization, all measurements
are to the metric system.
Other countries have their own standards
that would relate to specific products such
as aircraft and automotive. In the USA
other standards, including NAS (National
Aero Space) and SAE (Society of Automotive
Engineers), are related to those types
Here are some examples of differences
in metric jobber drills versus inch jobber
- A metric drill OAL is measured from
back of shank to point tip; an inch drill
is measured from back of shank to point
- OAL and flute length of a standard DIN
338 jobber drill can be shorter than an
inch jobber drill. The flute length in parparticular
should be noted when using an inch
drill bushing. The shorter flutes could end
inside the bushing, preventing chip evacuation.
- Metric drill OD tolerances are measured
in lower case letters such as h8; inch sizes
would be +. 0 to a minus tolerance.
- Metric tangs are sized differently and
will not fit into an inch collet.
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