Hi All

I'd very much like some advice on what is happening with my model and subsequent Gcode.

I want to face a new sacrificial board on my Chinese 3040 router. The model I've created allows for the four corners on the sacrificial board not to be machined as I have four bolts located at each corner. I'll machine those areas as a secondary function.

The model when running in Fusion looks good and simulates as designed. However when I generate the Gcode and run it on mach3, it adds a significant Z axis command that sends the spindle into the stratosphere, across then back down to begin the machining.

Any ideas why this would occur? I haven't added a command for the z axis to rise.

I do wonder if it is related to G28 G91 Z0 in line 5 and setting a home position.

I'd really like at attach the .tap file but cannot. Hope it's ok to post the Gcode below.

Thanks in advance. Apologies for any misuse of terms...I'm very much learning my way around Fusion 360 and Mach 3.
Shane

(CNC SURFACE CUT)
(T1 D=10. CR=0. - ZMIN=0. - FLAT END MILL)
G90 G94 G91.1 G40 G49 G17
G21
G28 G91 Z0.
G90


(2D POCKET2)
M5
M9
T1 M6
S5000 M3
G54
M8
G0 X78.694 Y-0.5
G43 Z20. H1
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G1 Z12.5 F1000.
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G3 Y0.5 I0. J0.5
G1 X75.75 Z5.945
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G1 X84.25 Z1.982
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G3 Y-3.015 I0. J-1.758
G1 X82.696 F1000.
G3 X83.015 Y-2.696 I0. J0.319
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M30