For machining the circular arc shown in the figure below on a $$NC$$ machine, the interpolation parameters $$(I.K)$$ and the incremental movements in the direction of the $$X$$ and $$Z$$ axes are programmed as

Consider the following statements:

The helical flute in a twist drill provides the necessary
$$1.$$ Clearance angle for the cutting edge.
$$2.$$ Rake angle for the cutting edge.
$$3.$$ Space for the chip to come out during drilling.
$$4.$$ Guidance for the drill to enter into the work piece.

Which of the statements given above are correct?

A job of the shape shown in the figure below is to be machined on a lathe. The tool best suited for machining of this job must have

A non standard thread of pitch $$3.175$$ $$mm$$ is to be cut on a lathe having lead screw of pitch $$6$$ $$mm.$$ A change gear set provided with the lathe has one gear each with the following number of teeth: $$20, 30, 40, 50, 60, 70, 80,$$ $$90, 100, 110, 120, 127.$$ The correct pairs of change gears $$\left( {a/b\,\,x\,\,c/d} \right)$$ for machining the given thread are (assuming that the transmission ratio of the rest of the kinematic train between the lathe spindle and lead screw is equal to