Drilling machines are specified according to their type.
A portable drilling machine is specified by the maximum diameter of the drill that it can handle.
The size of the sensitive and upright drilling machines are specified by the size of the largest workpiece that can be centered under the spindle. It is slightly smaller than twice the distance between the face of the column and the axis of the spindle.
Particulars such as maximum size of the drill that the machine can operate, diameter of the table, maximum travel of the spindle, numbers and range of spindle speeds and feeds available, morse taper number of the drill spindle, floor space required, weight of the machine, power input are also needed to specify the machine completely. The size of the radial drilling machine is specified by the diameter of the column and length of the radical arm.