The ram, basically a sliding member of the machine's overarm, enables the spindles to move in and out parallel to the movement of the saddle; i.e. in the Y direction. In the turret-ram styles, the entire ram overarm can pivot about the main upright axis of the column's backbone, thus positioning the spindle in an arc sweeping over the workpiece table to describe an arc. Being a function of the spindle-drive motor's proximity to the quill and spindle, it provides capability to tilt the spindle axis away from the vertical, either by inclining the Z-axis left and right, tilting it forward and aft, or both.

Typical operations are end milling, slotting, dovetailing, precision boring and tapping etc. “ Bridgeport ” is the name most usually associated with this very versatile type of machine.

In the universal version of this type of machines, addition of the capability for rotating the workpiece about the Z-axis, either through a rotary table or through a rotary vise mounted on the table, permits angular cutting.

This type of machines are generally built with high-power motors and heavier-duty construction.

This type of machine is sometimes called plain miller, which denotes that the table, typically long and narrow, is at a right angle to the spindle axis. Universal versions of horizontal-spindle machines incorporate a provision for rotating the table at angles up to about 30 o away from perpendicular to the spindle axis; a dividing head is often added as standard equipment for this style. The knee-type horizontal miller shares the knee-and-column construction with that kind of vertical miller. But, in many cases, it shares another vertical-miller feature: the vertical-spindle itself.

In the bed-type horizontal machines, the spindle rigidity gained by generous support of a horizontal-axis cutter is combined with the table rigidity inherent in fixed-beds. Often called manufacturing-type machines, fixed-bed horizontals indeed seem ideally suited for the limited versatility but high m.r.r typical of large-volume production.

This type of milling machines is most likely to be built in singlex, duplex, or triplex versions; the designations refer to the number of spindles employed. Dedicated, manufacturing-oriented machines are sometimes built with spindles located 90o or 180o to carve multiple faces of a single workpiece in single feed stroke.

Continuing in a progression toward greater power and cutting capacity but with more specialization and less versatility is the planer-type mill, which shares its basic construction principle with that of the planer. These types of machines are characterized by their capacity to accept large workpieces. Many feature multiple milling heads (rail heads mount vertically on the cross rails that straddle the table; side heads have horizontal spindles that simultaneously machine, say, the sides of box castings). Feed is provided by the longitudinal motion of the table.

Openside planer mills are designed for ease of workpiece loading and unloading and have a single upright column that supports the cross rail. This is in contrast to more-conventional double-column (or “bridge-type”) planer miller that can provide a high degree of structural rigidity.