For outside diameter turning on a lathe, which axis must be touched off and zeroed?

For outside diameter turning on a lathe, which axis must be touched off and zeroed?

• A. X axis
• B. Y axis
• C. Z axis
• D. A axis

Answer: (A)

Outside diameter work is a radial measurement: you’re controlling how far the cutting tool is from the spindle centerline. That distance lies along the X axis on a CNC lathe. By touch-offing the tool against the part and establishing a known X reference, you create a baseline from which all OD cuts are defined. Once X is zeroed relative to that surface, moving the tool in X changes the diameter you produce, because X is the radial position that sets the roundness of the part. The Z axis, in contrast, runs along the spindle and governs length along the part, not its diameter. The Y axis (when present) is a secondary lateral axis used on some machines for additional motion, but it isn’t the axis that defines the standard outside diameter in turning. The A axis is a rotary axis used for live tooling or rotary tables, not for the basic OD geometry. So, for reliably machining a specific outside diameter, you touch off and zero the X axis.

Outside diameter work is a radial measurement: you’re controlling how far the cutting tool is from the spindle centerline. That distance lies along the X axis on a CNC lathe. By touch-offing the tool against the part and establishing a known X reference, you create a baseline from which all OD cuts are defined. Once X is zeroed relative to that surface, moving the tool in X changes the diameter you produce, because X is the radial position that sets the roundness of the part.

The Z axis, in contrast, runs along the spindle and governs length along the part, not its diameter. The Y axis (when present) is a secondary lateral axis used on some machines for additional motion, but it isn’t the axis that defines the standard outside diameter in turning. The A axis is a rotary axis used for live tooling or rotary tables, not for the basic OD geometry.

So, for reliably machining a specific outside diameter, you touch off and zero the X axis.