(1) diameter: the diameter of the pilot bit is not very strict. The data listed in Table 3- 17- 1 are for reference.
Table 3- 17- 1
(2) The number of wing plates: most of them are double-wing plates inlaid with cemented carbide, which are suitable for soft rocks. There are also three wings and four wings, which work stably and are suitable for hard rock formations.
(3) Wing plate thickness: generally 40 ~ 50 mm. ..
(4) Wing plate shape: conical, suitable for hard rock stratum; Flat bottom shape is suitable for soft rock stratum; Fishtail shape is suitable for soft rock.