A toolhead assembly for a CNC machine displaceable along orthogonal x, y and z-axes generally consisting of a support assembly, a tool carrier supported on the support assembly having a rotatable tool axis and being displaceable relative to the support assembly between a first position wherein the tool axis is aligned with the z-axis and a second position wherein the tool axis is misaligned with the z-axis, structure for yieldably biasing the tool carrier assembly into the first position and structure responsive to a displacement of the tool carrier assembly to the second position for breaking an electrical grounding circuit of a controller operatively connected to the machine.