Radial Drilling Machine.—[Fig. 1680] represents a radial drilling machine, the column of which envelops a sleeve round which it may be swung or revolved, the sleeve extending some distance up from the base plate. The arm fits to the column and may be raised or lowered to any desired height to suit the work, the construction being as follows:—
Motion by belt is given to the spindle shown extending above the top of the column, and the pair of gears beneath it convey motion to the pair of bevels which drive the upper cone pulley which connects by belt to the lower one, which is provided with back gears to give the necessary changes of speed and power for the wide range of work the machine is intended for; the live spindle of the lower cone pulley extends past the collar and runs beneath the horizontal arm, giving motion to the drill spindle, which is carried in a sliding head. The spindle may be set at any required angle to the arm.
The vertical screw on the right hand of the column passes through a nut in the column, so that by throwing the gearing at the upper end of the screw into action, the arm may be raised or lowered by power.
The vertical rod appearing in the front of the column and having an arm at its top, is for putting this gearing in or out of action, the arm being raised or lowered according to the direction in which the rod is operated by the lever handle shown upon it, and in front of the column. The gearing at the top of the raising and lowering screw is constructed on the principle that was shown in [Fig. 566], for reversing the direction of a lathe feed.
The capacity to swing the drill spindle at an angle enables the drilling of long work such as the flanges of pipes, by setting the pipe at an angle and swinging the spindle so as to stand parallel to it, while the facility with which the arm may be moved to any required position makes it easier to move the arm to the work, so that the latter will require but one chucking or setting.
Radial drilling machines are of various constructions. In some the drilling head is carried by an arm standing at a right angle to the main column or frame, and is capable of being moved to any required position upon the length of this arm. The arm itself is sometimes made capable of swinging upon its own axis, as shown in [Fig. 1682].
It is also capable of being adjusted at any height from the bed or base plate upon which the upright or main frame sits, or above the work table when one is used as in the figure.
The advantage given by these facilities is that a heavy piece of work may be set upon the base plate or work table, and be drilled in various places without requiring to be moved.
