A cross slide is a machine tool part that allows movement of a tool post or workpiece along two perpendicular planes during machining. Cross slides fall into two categories: those that support tool bits such as lathe cross slides and workpiece supports used on milling machines and drill presses. A lathe cross slide serves as a mobile platform for a static tool bit when performing facing operations. The milling machine or drill press cross slide moves a workpiece across the axis of a revolving tool bit to effect cutting operations. Both types typically achieve their motion by means of two lead screw mechanisms which allow for a high degree of control and very precise advancement.
Precision machine tools such as lathes and milling machines rely on accurate introduction and advancement of their respective tool bits onto the face of the workpiece. The main difference between the two types of machine is the relationship between workpiece and tool bit. Lathes spin the workpiece in a precision chuck while the tool bit remains static in a tool post. Machining is achieved by moving the tool bit against the workpiece to cut material away. Milling machines feature a revolving tool bit which is held static while the workpiece is advanced against it to remove material.
Lathe cross slides are mounted on the saddle of the machine which straddles the bed of the lathe and traverses the length on the same axis as the rotating workpiece. The cross slide in turn offers a mounting platform for the tool post in which the tool bit is held. When the saddle moves along the length of the bed, the slide and tool post move with it to make parallel cuts. When facing is necessary, the cross slide may be adjusted across the width of the lathe bed to cut the face of the workpiece. The cross slide may also be adjusted to move along the length of the saddle as well for additional fine adjustment.
Milling machine and drill press cross slides afford the same level of fine advancement control as lathe slides. The major difference between the two however, is that the milling machine slide holds and advances the workpiece, and the tool bit rotates to make the cut. This feature means that a milling machine cross slide will incorporate a specially designed vice that supports and immobilizes the workpiece. By turning the lead screw cranks, the workpiece is advanced to make contact with the tool bit to achieve the cut. This type of cross slide can also be adjusted along two perpendicular planes to give the operator a high degree of flexibility and accuracy in the machining of the workpiece.