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

The cutting portion of a drill is to be welded to its shank. The process best suited for this is