槽轴线
加工槽时刀具中心所走过的直线。对大多数变幅杆而言，槽轴线与螺柱轴线平行。在某些情况下（例如双槽条形变幅杆），槽轴线可以是倾斜的。
Slot axis
The line traversed by the center of the cutter while machining a slot. For most horns, the slot axis is parallel to the stud axis. In some cases (e.g., 2-slotted bar horns) the slot axis may be angled.