# Mathematical Processing in Programming of NC Turning in Machine Tool Plant 2.6.1 Base point and base point calculation
In the process of programming, the coordinate value of some points passed by the tool movement may not be directly marked in the parts drawing, which requires calculation of related data to calculate its coordinate value. These coordinate points are the intersection or tangent points between different geometrical lines on the contour of the part, such as the intersection point or tangent point of a straight line and a straight line, an intersection or tangent point of a straight line and an arc, an intersection or tangent point of an arc and an arc, etc. It is called the base point in CNC machining. The base point is generally the starting point or end point of a certain segment of the knife’s motion path in programming.
Commonly used methods of base point calculation are:
(1) Calculate manually according to the known conditions given on the part drawing. That is, according to the given size on the part drawing, the relevant knowledge of algebra or geometry is used to manually calculate the relevant number. The simple calculation of the coordinates of the edited point can be obtained by manual methods, and the calculation of the tomb point coordinate value is very complicated in the calculation process, in order to improve the efficiency of calculating the base point. Some paintings can be used
Software, such as direct access in AutoCAD.
(2) Use CAD/CAM software to take directly from the drawing. Now most of the drawing is done in AutoCAD and other drawing software. You can use the functions of these CAD/CAM software to directly mark and check the parts in the drawing. The coordinate values ​​of certain points on the contour.