CNC Lathe | G50.2 and G51.2 | Polygon Turning

Polygon Turning Introduction

When rotating the workpiece and a tool at a certain ratio, a polygonal figure can be machined.

For example, by changing conditions such as rotation ratio of workpiece and tool as well as the number of cutters, a square or hexagon can be machined. Under certain circumstances, the machining time can be reduced compared to machining using C and X axis in polar coordinate interpolation.

Due to the nature of such kind of machining however, the machined figure is not exactly polygonal. Typical applications are the heads of square and/or hexagon bolts or nuts.

Hexagon bolt

G50.2 and G51.2 Format

G51.2 P…Q…;
P, Q: Rotation ratio (spindle / Y axis)
Setting range: Integer 1 to 9 for both P and Q
The sign of address Q is used to specify the Y axis rotation direction.

G50.2 and G51.2 Examples

Program Example – 1 – G50.2 and G51.2

G00 X120.0 Z30.0 S1200.0 M03; set workpiece rotation speed to 1200 rmp
G51.2 P1 Q2 ; start tool rotation (2400 rpm)
G01 X80.0 F10.0 ; X axis infeed
G04 X2. ;
G00 X120.0 ; X axis retract
G50.2 ; stop tool rotation
M05 ; Spindle stop

G50.2 and G51.2 need to be specified in seperate blocks.

Polygonal turning