The horizontal boring mill or HBM actually predates the milling machine. The boring mill was invented in 1775 by John Wilkinson. The milling machine, on the other hand was invented in 1818 by Eli Whitney. The boring mill was originally designed to do nothing more than bore deep holes through large workpieces. The HBM was eventually converted to enable it not only to mill, but to drill and even tap holes. Since it is typically much bigger than its milling machine counterpart, it can easily handle the larger workpieces. At the same time, it can be used to machine workpieces that are very small. In fact, it is not uncommon to have two or three different small to medium sized jobs on the HBM table at the same time.The size of the spindle and its accompanying drive motor is typically much bigger than a milling machine and this in itself results in a tremendous increase in horsepower availability. <number>
This is a medium sized Boring Mill equipped with an indexable rotary table. With the rotary table, four sizes of a cube-shaped workpiece could be machined in one set-up. It would also enable the operator to bore a hole from two opposite sides and have the hole meet at a precise location.<number>
This large behemoth is designed to machine workpieces too large to mount on a machine table. The work piece is mounted to a base and the machine moves back and forth past it on floor rails. Hence the name, floor-type boring mill.Notice the operator just to the right of the control pendant. The head of the Boring Mill moves up and down the face. A ladder is attached so as to allow the operator to climb down if the machine head has been raised. Not your typical Bridgeport.