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G-Code, CAD, and CAM discussions / G18 and G02 G03 problem

« on: April 02, 2013, 01:59:09 PM »

This is my second G-code program ever, so please forgive me if I did something stupid

The part should be symmetrical, a slot with 2 opposing "fingers".   The bottom arc of the finger closer to the origin always goes clockwise (I think) whether I use G02 or G03....  Am I doing something wrong, or is this a Mach3 bug?   The problem arc is at the bottom of the program with a (******) comment above it.

I'm using IJ in incremental mode.

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G20 (inches) G90 (absolute coords) G64 (best speed path)
M6 T3             (0.375 end mill)
G40
F15             (feed rate)
G00 Z0.1
G00 X 0.570 Y-0.190   
M98 P100 L3         (slot the stock)
(G00 Z2)         (retract for tool change)

M6 T6            (Enco 327-1933  1/2X3/64 NARROW USA STRTOOTH KEY CUT .047  )

G00 X 0.928 Y-0.260 (rough undercut)
G00 Z-0.156
G01 Y 0.760
G00 X 0.572
G01 Y-0.260

G00 X 0.928
G00 Z-0.129
G01 Y 0.760
G00 X 0.572
G01 Y-0.260

G00 X 0.938 Y-0.260 (finish undercut)
G00 Z-0.156
G01 Y 0.760
G00 X 0.562
G01 Y-0.260

G00 X 0.938
G00 Z-0.129
G01 Y 0.760
G00 X 0.562
G01 Y-0.260

G00 X 0.908 Y 0
M98 P200 L11    (round fingers on right side)
G91 G01 Y 0.025
G90
G00 x 0.592
M98 P300 L11    (round fingers on left side)

G00 X 0.750       (get in the middle to retract)
G00 Z0.1
M30    

(----------------------------------------------------------------)
O100                (Cut the slot)
G40
G91 G01 Z-.052   (conventional milling... maybe try climb)
G90
G01 Y 0.690
G01 X 0.930
G01 Y-0.190
G01 X 0.570
M99

(----------------------------------------------------------------)
O200               (undercut the finger right side)
G40 G90               
G91 G01 Y 0.025
G90
G18              (XZ plane)
G03 X 0.867 Z-0.088 K 0.041      (90 degree arc)
G01 Z -0.042               (Move up the width of the keyway cutter)
G03 X 0.908 Z-0.001 I 0.041      (90 degree arc)
G91 G01 Y 0.025
G90
G02 X 0.867 Z-0.042 K-0.041      (90 degree arc)
G01 Z -0.088               (Move up the width of the keyway cutter)
G02 X 0.908 Z-0.129 I 0.041      (90 degree arc)
G17            (XY plane)
M99

(----------------------------------------------------------------)
O300            (undercut the fingerleft side)
G40 G90               
G91 G01 Y -0.025
G90
G18              (XZ plane)
G02 X 0.633 Z-0.088 K 0.041      (90 degree arc)
G01 Z -0.042               (Move up the width of the keyway cutter)
G02 X 0.592 Z-0.001 I -0.041      (90 degree arc)
G91 G01 Y -0.025
G90
G03 X 0.633 Z-0.042 K-0.041      (90 degree arc)
G01 Z -0.088         (Move up the width of the keyway cutter)


(************** the following line always goes the wrong way whether I use G02 or G03)
G03 X 0.592 Z-0.129 I -0.041      (90 degree arc)


G17            (XY plane)
M99
            


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