Drill Bits - Hitachi DH 24PE (S) Technical Data And Service Manual

8-4. Drill Bits

The chuck section is designed exclusively for the popular and widely available SDS-plus shank bits, as shown in
Fig. 9. 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 coming off. Compared with a conventional design that uses two needle rollers
to both transmit rotating torque and prevent the bit from coming off, this new design 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 to a
depth of 30 mm. If reground before the end of its service life, the drill bit will continue to provide efficient drilling.
Figure 10 shows the regrinding angle.
60˚
Section A-B'
Steel ball
Fig. 9
Regrinding angle of drill bit
a : b = 1 : 2
25˚
Fig. 10
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A
A'
Cylinder
Section of the chuck section
A
B
Key slot (two pieces)
Section A-A'
Key rail (two pieces)
Ball holder
Rotation
direction
θ
130˚