This section is from the book "Lathe Design, Construction And Operation, With Practical Examples Of The Lathe Work", by Oscar E. Perrigo. Also available from Amazon: Lathe Design: Construction And Operation.
A lathe may be used as a horizontal drilling machine and both sensitive and large drill presses are really developments of the lathe. The drill press is a vertical lathe without any provision for mounting turning tools. The use of a horizontal table on a drill press makes it more suitable for handling large and heavy work as the weight of the pieces drilled serve to hold them in place on the table. A lathe can be used in drilling, only it is more difficult to support the work when it is bulky or heavy. The simplest method of drilling is to place the drill in the lathe chuck and hold the piece to be drilled by hand against the drill pad held in the tail stock, using the tail stock hand wheel to feed the work against the drill. In this case, the drill turns as it does in a drilling machine and the work remains stationary. The lathe chuck or face plate is often employed to hold the work to be drilled as at Fig. 322-A while the drill chuck is supported by the tail stock. The method of supporting a piece when a long hole is to be drilled by using a center rest or back rest clamped to the ways of the lathe is clearly shown at Fig. 322-B. The use of a centering tool which is held in the tool post is outlined in this view. The drill is held by the tail stock in the same manner as at A except that in many cases, when the drill is very long, the tool post may be used to support the drill after it has entered the bar far enough to center itself.
Fig. 322. - Methods of Drilling in the Lathe.