The ZC mode is started with the command (~PLZC).
Before entering this command the live tool must be located on the negative X side of the part, with its spindle centerline parallel to the lathe's X axis.

On entry, the tool is centered at X0 and Y0 position in the virtual milling machine, so before switching planes you need to locate the Z and C axes to the location you want to be X0,Y0 on the part surface. NOTE: You must accommodate the tool diameter, and program accordingly.

X positive motion is to the right (toward the spindle face) as viewed from the live spindle's point of view, and Y positive motion is up from the live tool's point of view.

Because most lathe programming refers to radial positions as diameters, Z dimensions are given as the diameter of the cylinder the tool tip would touch. The virtual mill's Z axis is set to the X position prior to the plane switch, but the sign is inverted, so that a positive Z move moves the tool tip away from the part center.

For example, in this code:

m19
T11(call up live tool)
x-1z.5 (tool is at a 1inch diameter on -X side of part)
z-.2
(~plzc) plane switch mill position is x0,y0,z1
(f5z.85) tool tip moves in to cut at a diameter of .85

Note that the z.85 command moves the tool tip in toward the center of the part.

C-Axis ZC Plane Switching Examples

The following examples were cut in a 7/8" delrin bar with a 1/16" end mill.

Note:if you copy these programs, do not include comments in the plane switched section. Nothing is allowed in the plane-switched program except the program statements described above.