Progressing a little further, I'm now wanting to cut a circular 'pocket' - well the outside - and I'd like it to be 22mm deep.

The top of the work is at Z= -52 so starting a Z= -51 to provide a 'Z lead-in' so that there is no plunge entry, I'm using G2 with the Z parameter changing at each pass by 2mm I want to get down to Z = -74 but, in the simulation, I'm getting a [Soft Limits] error when Z is below -71

This is the program I'm simulating :

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O0010 (Bore ready to Thread Mill 80 x 3.NC)

N10 (Author - JG - 24 July 2020)

N20 (for Denford MicroRouter Compact under Mach3 V2)

N30 (Thread Milling 80 x 3mm - bore = 76.75 - R= 38.376)

N40 (T3 D=8 Flatt End Mill to remove centre)

N45 (T4 D=24.32 Thread Mill cutter)

N50 (units mm)

N60 (X & Y 0 in MACHINE centre)

(X Min = -200, X Max +200)

(Y Min = -100, Y Max = +100)

(Z Max = 0 at top Z Min = -100)

N100 G17 G21 G00 (set up XY Plane & Metric - fast traverse)

N110 X34.0762 Y0 Z-51 (move XY & Z - Determine Z by reference to work)

N120 S8000 M3 (set spindle speed & start spindle)

N130 F3000 (set feed rate - simulation )

N140 G2 I-34.0762 J0 Z-52 (cut Circle about 0,0 feeding Z 2mm)

N150 I-34.0762 J0 Z-54

N160 I-34.0762 J0 Z-56

N170 I-34.0762 J0 Z-58

N180 I-34.0762 J0 Z-60

N190 I-34.0762 J0 Z-62

N200 I-34.0762 J0 Z-64

N210 I-34.0762 J0 Z-66

N220 I-34.0762 J0 Z-68

N230 I-34.0762 J0 Z-70

N240 I-34.0762 J0 Z-71

N250 I-34.0762 J0

(N260 I-34.0762 J0) (Cut flat bottom NO Z change)

N1450 M05 (Turn spindle off)

N1500 G00 X0 Y0 Z0 (move tool at fast rate to 0 0 0)

N1510 M30 (Close Program)

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The error appears if I set Z in N240 to -72 -- I would expect (in theory) to be able to go to -100, there will of course be other factors such as tool length that will preclude that, but I'm not setting a tool Nº which might confuse the issue anywhere.

A separate question - after each rotation (line of G-Code N140 - N240) there is a tool 'dwell'; can this be eliminated so that the program simply runs a continuous cycle ?