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This cycle is used when NC code is created manually.

The picture shows a part about to have a groove machined in its surface.

A G0 command brings the right-hand corner of the tool to starting position P0. The G86 command will make the tool move forward, back and left repeatedly to cut the groove. The movements continue until the left-hand corner of the tool tip reaches target point P1 where the cycle ends. Each leftward movement is 0.9 x tool width. WELturn picks up the tool width from data stored when the offsets for the tool are measured. Cutting movements will be at the cutting feed rate. All other movements will be at rapid traverse rate. Each time the tool reaches the bottom of the groove there is a dwell (pause) which ensures the whole circumference of the groove is cut.

The best way to appreciate the cycle is to get WELturn to simulate the G86 illustration below. Copy everything between the % symbols, including the % symbols, into UNCONVERTED WINHELP MACRO:!EP(`C:\\windows\\notepad.exe',0)Notepad. Save the file in C:\WELturn\Turndata with the extension .cnc

Go into WELturn and run the file in simulation mode only: do not try to machine anything. Observe the path of the tool as it executes the cycle

G86 illustration (metric)
%
*Billet Diameter 25
N10 T1
N20 S950
N30 G0 X24 Z5
N40 G1 X24 Z-30 F100
N50 G0 X25 Z-30
N60 G0 X25 Z5
N70 T6
N80 S950
N90 G0 X25 Z-5
N100 G86 X10 Z-25 F100 H50
%

Line N90 gives point P0 where the grooving cycle starts.

In line N100, X10 Z-25 give point P1. When the tool reaches P1 and the grooving is completed, the tool returns to P0.

The full format of the G86 command is:

N(line number) G86 X(co-ord of P1) Z (co-ord of P1) F(cutting feed rate)

For example:
N90 G86 X20 Z-40 F100

Note: the X co-ordinate is the diameter at P1 and the Z co-ordinate is its distance Z left (notice the minus sign) of the centre of the end of the billet, not the finished part. The centre of the end of the billet is the location of the origin, X = 0, Z = 0. All co-ordinates are absolute values measured from this point.

If desired and if it is wide enough, the groove can be cut slightly undersize with a small amount of material left for lower feed rate finishing cuts by right and left hand tools.

Canned Cycles