Drill Bits - Hitachi DH 20PB Technical Data And Service Manual

8-5. Drill Bits

The chuck section is designed exclusively for the popular and widely available SDS-plus shank bits, as shown in
Fig. 4. Rotating torque is transmitted to the drill bit by two key rails provided in the tool holding section. A steel
ball is used to prevent the bit from falling out. Compared with the conventional structure that uses two needle
rollers to both transmit rotating torque and prevent the bit from falling out, this new structure reduces damage to
the shank of the drill bit and extends the service life of the chuck section.
Shape of SDS-plus shank bit
The service life of a drill bit with a diameter of 8 mm is approximately 300 holes when drilling into concrete with a
depth of 30 mm. If reground before the end of its service life, the drill bit will continue to provide efficient drilling.
Fig. 5 shows the regrinding angle.
60
Section A-B
Fig. 4
Regrinding angle of drill bit
a : b = 1 : 2
25
Fig. 5
--- 15 ---
A
A'
Key rail (two pieces)
Steel ball
Cylinder
Section of the chuck section
A
B
130
Key slot (two pieces)
Section A-A'
Ball holder
Rotation
direction
θ