S O M T A P 1 2 C A T A L O G U E
49
STRAIGHT
SHANK
DRILLS
Drill Terminology
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points are available which include web thinning, notch points, split points, double angle points, spur and
brad points etc.
Tangs and Flats
Tangs can be produced to DIN, ASA and ISO, also special whistle notch flats on shanks.
Step Drills
Standard drills can be modified into step drills.
Surface Treatments
A full range of surface treatments including nitriding, stream oxide, chemical blackening, gold oxide and
various titanium coatings are available.
Specify whether drill is to be Step or Subland Type.
D = Diameter of large, fluted section.
P = Diameter of small, fluted section.
A= Shank Diameter.
L = Overall Length.
F = Flute Length.
E = Length of Small Diameter. This is measured from the extreme point to the bottom corner of the step
angle.
X°= Included angle of the step angle.
S = Shank Length.
It is possible to drill two or more diameters in a hole on one operation with a correctly designed
drill and these are often used in mass production engineering.
Some of the hole types that can be drilled in a single operation.
MULTIPLE DIAMETER DRILLS
D
E
S
L
F
A
P
X°
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