straddle-mill

from The Century Dictionary.

• noun A revolving milling-machine cutter, either solid or made up of several cutters set side by side in a gang, which will cut or finish the top and sides of the work at the same time, when it is presented to the cutters in the plane in which they revolve, or at right angles to their common axis. This can only be done when the outside cutters have cutting-edges on their inside faces, or appear to straddle the work. The straddle-mill generally faces the top and sides of the work at the same time.