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8-6. 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 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.
Ball holder
Key rail (two pieces)
Key slot (two pieces)
Section A-A'
Steel ball
Retainer sleeve
A
A'
Shape of SDS-plus shank bit
Section of the chuck section
Fig. 4
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.
Fig. 5 shows the regrinding angle.
Regrinding angle of drill bit
Fig. 5
a : b = 1 : 2
Rotation
direction
60
25
a
b
A
B
Section A-B
130
