Generally, there are six degrees of freedom when the workpiece is not positioned in space,X/ Y/Z three linear displacement degrees of freedom and their corresponding A/B/C three rotational displacement degrees of freedom.These six degrees of freedom are usually expressed as three linear axes in cartesian coordinate system X/Y/Z,their corresponding A/B/C is used to express the three rotation axes.

Such as multi-axis CNC machine tools,that is,the number of axes shall be planned and set according to the machining object when the machining center was designed.

Three axis CNC machining centers with X/Y/Z linear displacement axes are common in the market. The so-called four-axis machining center is generally added to a rotating axis, usually known as the fourth axis,that is the four-axis machining center.Compared with the three-axis machining center, there is an additional rotating shaft,if this axis rotating around the X-axis then it's called the A-axis,

If it's rotating around the Y-axis then we called the B-axis.

In addition to X/Y/Z,there's also a rotation axis which is used to make things like circles,the extra axis usually comes out with an instruction like A/B/C.

Front and back in the axis of the cylinder, left and right in the end. Clamp a cylinder on four axes, pull horizontally,front and back can be divided,left and right are determined according to the workpiece parts and programming schedule.

At zero degrees, find the center of the x-y axis(hold a round rod on four axes),then rotate the four axes by 90 degrees, using a table or a standard rod to make the principal axis coincide with the end face,so the distance from the original origin to the end face of the four-axis circle 90 degrees is the radius of rotation.

In general, there are more single-sided datum in the direction of X, and there are also some points in the direction of Y,the rod should be clamped on the fourth axis in the direction of Z.Use a dial gauge to measure the height of the countertop and the center of the rod,the height difference measured is corrected into the coordinate system firstly,this allows the tool knife to be pointed directly at the workbench.