Hi Rich,
Thank you for this post! Brand new to using a CNC / Fusion / G-Code / Mach3...and loving it!
Everything was working great except for the fact that on every program (G Code created with Fusion 360 Generic Mach3 post process) the machine would move to the starting point without raising the bit off Z zero...resulting in a nice straight groove across the face of the stock...or, if I manually raised the Z a little and started the program from there then it wouldn't cut all the way through the stock. Also, at the end of the program it would only raise to the Z zero height and then return to X zero and Y zero resulting in another nice straight groove across the face of the finished part. GAAAAAH
My machine is a simple 3-axis router DIY setup WITHOUT limit/home switches and I haven't learned enough yet to use soft limits, work offsets, etc. etc. Like you said, trying to start as simple as possible.
Taking your advice I changed the start of the program from this:
(CAM CLAMP)
(1)
(T1 D=0.25 CR=0. - ZMIN=-0.67 - FLAT END MILL)
G90 G94 G91.1 G40 G49 G17
G20
G28 G91 Z0.
G90
(2D CONTOUR1)
M5
M9
T1 M6
S10000 M3
G54
M9
G0 X2.0088 Y2.8883
G43 Z0.65 H1
Z0.25
G1 Z-0.125 F10.
X2.016 Y2.9256 F20.
etc. etc. etc.
To this instead:
G20
G90
G0 Z0.25
G0 X2.0088 Y2.8883
G1 Z-0.125 F10.
X2.016 Y2.9256 F20.
etc. etc. etc.
If I have my head wrapped around this:
G20 is important because that defines programming in inches (the units the part is designed with)
G90 is absolute reference and important for simple simple
I don't fully understand what the Z0.25 was in the original code but I 'moved' it up and put G0 in there to raise the Z first and foremost
Then it moves to starting point, Z drops in and off it goes.
The other key part was at the end...the original Fusion code has:
M9
G28 G91 Z0.
G28 X0. Y0.
M30
And I just deleted all of it...granted the machine just 'stops' at the end of program and doesn't return to home or anything but that prevents any grooves getting cut in the finished part.
Is there a G code (G30?) with maybe G0 Z1.0 to raise the bit up and then move the router back to the home starting point?
Anyway, long post but thank you again!