Programming of control points

Programming of control points is done with linear blocks (G00, G01), whose target points are used as control points.

It must be ensured that the curve runs through the control points only at the start and end.

Programming example

N10 #SET SPLINETYPE BSPLINE 
N20 G01 X0 Y50 Z0 F10000 
N30 #SET SPLINE ON 
N40 X3 Y25 
N50 X15 Y15 
N60 X23 Y12 
N70 X25 Y25 
N80 X30 Y35 
N90 X50 Y37.5 
N100 X55 Y32.5 
N110 X58 Y12 
N120 X70 Y12 
N130 X77.5 Y10 
N140 X90 Y35 
N150 X100 Y37.5 
N160 #SET SPLINE OFF 
N170 M30

The following figure shows the contour resulting from the Programming example:

Programming of control points 1:
Fig. 11.10: Contour resulting from programming example

The figure shows the smoothing property of a B spline curve, especially for blocks N120/N130. Moreover, it shows that the curve will not pass through the control points. However, the polygon resulting from connecting the control points will give an idea of the actual shape of the curve.

Programming of control points 2:

In case of a B spline curve, it is not possible to directly specify the tangents at the curve ends. However, because the tangents of the curve is the same as the tangent of the corresponding moving blocks at the curve end, tangents may be given by programming the moving blocks at the curve end appropriately.