Classification depends on the orientation of the spindle axis, not the bed angle. A slant-bed lathe with a horizontal spindle axis is generally treated as a horizontal lathe. If the spindle axis is inclined or vertical, the machine would fall under the non-horizontal category. Manufacturer specifications confirming spindle axis orientation are the key supporting document.

Both vertical turning lathes and vertical boring mills with numerical control for metal removal can fall within this heading, as the classification criterion is spindle orientation and NC capability rather than the specific turning or boring function. However, machines primarily designed for boring rather than turning may warrant separate classification analysis, and a binding ruling from CBP can provide certainty for high-value equipment.