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G-Code, CAD, and CAM discussions / Newbie questions about circle pocket cutting
« on: October 15, 2008, 04:38:15 PM »
Hello all. I recently bought a Zenbot from ebay, and a Xylotec control board, and of course Mach3! I'm trying to learn gcode well enough to create some small circular parts in Plexiglas, so I'm posting here to hopefully learn from the collective wisdom of others. 
I found the circular pocket wizard, and after some messing around with it I managed to cut a part that's very close to what I need. But, I don't understand what it's doing, just that "it works" -- which is a problem when I want to tweak something.
For example, I generated the meat of the gcode below with the wizard, then added some stuff at the end to finish up the part. But now I want to try cutting the main circular pocket 1/64" smaller in diameter, to see if that provides a snugger fit. Seems like that should be a simple change, but I'm at a loss. I could start the wizard over again and make all new code but that's kind of buying a fish instead of learning to fish, if you know what I mean. Is there a wizard tutorial somewhere that explains how these arcs work? I found several general gcode tutorials on the wider internet, but it seems many programs use different gcode syntax, and I want something Mach3 specific.
Secondly, once this is perfect I want to stick it in a subroutine. I'm going to want to cut many of these parts out of a single sheet of Plexiglas, so I figure I can have a main program that's just "move to location, call routine to cut part, move to next location, call routine, etc." But the wizard spits out absolute coordinates, how can I convert them to relative coordinates so they can go in a subroutine? Or is there a better way to accomplish what I'm trying to do?
I appreciate any suggestions. Thanks!
I found the circular pocket wizard, and after some messing around with it I managed to cut a part that's very close to what I need. But, I don't understand what it's doing, just that "it works" -- which is a problem when I want to tweak something.
For example, I generated the meat of the gcode below with the wizard, then added some stuff at the end to finish up the part. But now I want to try cutting the main circular pocket 1/64" smaller in diameter, to see if that provides a snugger fit. Seems like that should be a simple change, but I'm at a loss. I could start the wizard over again and make all new code but that's kind of buying a fish instead of learning to fish, if you know what I mean.
Is there a wizard tutorial somewhere that explains how these arcs work? I found several general gcode tutorials on the wider internet, but it seems many programs use different gcode syntax, and I want something Mach3 specific.Secondly, once this is perfect I want to stick it in a subroutine. I'm going to want to cut many of these parts out of a single sheet of Plexiglas, so I figure I can have a main program that's just "move to location, call routine to cut part, move to next location, call routine, etc." But the wizard spits out absolute coordinates, how can I convert them to relative coordinates so they can go in a subroutine? Or is there a better way to accomplish what I'm trying to do?
I appreciate any suggestions. Thanks!
Code: [Select]
(=== Initialization stuff ===)
G0 G49 G40 G17 G80 G50 G90
M6 T1(TOOL DIA.0.125)
G64
G20 (Inch)
M04 S0
G00 G43 H1 Z0.1
X0 Y0
(=== Magic voodoo arcs generated by the wizard, to cut main recess ===)
G01 Z-0.0625 F3
G3 Y0 X0.1187 R0.0594 F5
Y0 X-0.1187 R0.1187
Y0 X0.2374 R0.1781
Y0 X-0.2374 R0.2374
Y0 X0.3561 R0.2968
Y0 X-0.3561 R0.3561
Y0 X0.4375 R0.3968
Y0 X-0.4375 R0.4375
X0.4375 Y0 R0.4375
Y0.0625 X0.375 R0.0625
G00 Z0.1
X0 Y0
G01 Z-0.125 F3
G3 Y0 X0.1187 R0.0594 F5
Y0 X-0.1187 R0.1187
Y0 X0.2374 R0.1781
Y0 X-0.2374 R0.2374
Y0 X0.3561 R0.2968
Y0 X-0.3561 R0.3561
Y0 X0.4375 R0.3968
Y0 X-0.4375 R0.4375
X0.4375 Y0 R0.4375
Y0.0625 X0.375 R0.0625
G00 Z0.1
X0 Y0
(=== Smaller recess-within-recess, written by hand ===)
G01 Z-0.15625 F3
X0.09375
G3 I-0.09375 F5
G00 Z0.1
X0 Y0
(=== Outer cut to remove part from material, written by hand ===)
X0.625
G01 Z-0.0625 F3
G3 I-0.625 F5
G01 Z-0.125 F3
G3 I-0.625 F5
G01 Z-0.1875 F3
G3 I-0.625 F5
G01 Z-0.210 F3
G3 I-0.625 F5
(=== wrap up ===)
G00 Z0.1
X0 Y0
M5 M9
M30