Why is a milling machine called a universal milling machine?

 We had a big old Kearney-Trecker Universal mill at the city shop. It was called a Universal Milling Machine because it had both a horizontal and a vertical spindle.

Imagine the front of the mill looks like a typical knee mill, with a table that goes up and down in Z and side to side in X, as well as in and out in Y dimension.

Above this table is a horizontal 50 taper spindle, with a separate set of controls for spindle speed and direction. This is a big beefy machine, much heavier duty that a typical Bridgeport. The motor is not reversible like a Bridgeport, and there’s no quill.

Above that horizontal spindle is a ram, traveling on dovtail ways. At one end of the ram is a drive motor, and at the other end is an angle head which houses another 50 taper spindle, that can be rotated to either side as well as vertically. Another set of controls on the other side ran this spindle.

We used this machine for heavy milling cuts with a face mill, mostly, because it was so solid it would throw some serious blue chips. Or, the spindle could be pulled off and a support bearing head installed on the ways that would support a heavy bar in the horizontal spindle for line-boring, or gang milling with a stack of wheel cutters.

So that is why it is called a Universal Mill. It has both spindles, and, with the proper attachments and accessories, it can do anything you want done on a manual mill. The reason they are scarce these days is because they are typically slow, and take a long time to set up, and a cabinet full of stuff to take advantage of their capabilities. They are relics from an earlier time.