4

Figure (a) Single-flight auger bit with cutting blade for soils, (b) single-flight auger bit with hard-metal cutting teeth for hard soils, hardpan, and rock, and (c) cast

steel heavy-duty auger bit for hardpan and rock (Source: Woodward et aI., 1972)

Figure 17.5 A 30 0 underreamer with blade cutters for soils that can be cut readily (Source: Woodward et aI., 1972)