A Throwaway carbide insert was used to machine a steel work pieces with a cutting speed of $$60$$ $$m/min,$$ tool life of $$40$$ minutes was observed, when the cutting speed was increased to $$100$$ $$m/min,$$ the tool life decreased to $$10$$ minutes. The cutting speed for maximum productivity, if tool change time is $$2$$ minutes is

Helix angle of fast helix drill is normally

$$3$$ blocks of $${B_1},\,\,{B_2},\,\,{B_3}$$ are to be inserted in a channel of width $$'S'$$ maintaining a minimum gap of width $$T=0.125mm,$$ as shown in fig. For $$P = 18.75 \pm 0.08,\,$$ $$\,Q = 25.00 \pm 0.12,\,$$ $$\,R = 28.125 \pm 0.1$$ and $$S=72.35+X.$$ The tolerance $$' X '$$ is _______________.

In a point to point control $$NC$$ machine, the slides are positioned by an integrally mounted stepper motor drive. If the specification of the motor is $$1$$ deg/pulse, and the pitch of the lead screw is $$3.6$$ $$mm,$$ what is the expected positioning accuracy?