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General Mach Discussion / Re: I need help to make this subrutine run.
« on: December 06, 2010, 10:45:14 PM »
It’s all in the way G2 and G3 are implemented. For example in G90 (Abs) mode your line
g2 x0 y1.0215 i0 j-1.0215 z-.170
tells Mach to draw a clockwise arc starting at the current position, (the last position before this line which in this case is X0, Y1.0215) and ending at the position specified in this G2 line, (which is also X0, Y1.0215). The I value is the X distance from the starting point to the arc center, (X0 + 0 = 0) and the J is the Y distance from the starting point to the arc center, (Y1.0215 – 1.0215 = 0) thus the arc center based on the STARTING point is X0, Y0. Since the starting and end points are the same, obviously they will both have the same radius and everything is fine.
Now look at the same case but with G91 (Inc) active. Now the absolute values in line
g2 x0 y1.0215 i0 j-1.0215 z-.170
are redefined as the previous value shifted by the amount specified in this line i.e., the new X is the old X(0) + 0 = 0, the new Y is the old Y(1.0215) + 1.0215 = 2.0430 and the new Z is the old Z(0) -.170 = -.170. Thus in absolute mode the line now means
g2 x0 y2.043 i0 j-1.0215 z-.170.
The start point is still X0, Y1.0215 (from the preceding lines) but now the end point has changed to X0, Y2.0430 thus the error message that the start and end radius doesn’t agree. The I and J modes are handled differently. They aren’t affected by G90 or G91. Their mode is set independently in Config / General Config and will normally be set to Inc. That’s why just changing the Y1.0215 to Y0 fixes the problem in that line. It no longer changes the end point, still retains the same radius but allows the Z to increment as intended.
HTH,
Al
g2 x0 y1.0215 i0 j-1.0215 z-.170
tells Mach to draw a clockwise arc starting at the current position, (the last position before this line which in this case is X0, Y1.0215) and ending at the position specified in this G2 line, (which is also X0, Y1.0215). The I value is the X distance from the starting point to the arc center, (X0 + 0 = 0) and the J is the Y distance from the starting point to the arc center, (Y1.0215 – 1.0215 = 0) thus the arc center based on the STARTING point is X0, Y0. Since the starting and end points are the same, obviously they will both have the same radius and everything is fine.
Now look at the same case but with G91 (Inc) active. Now the absolute values in line
g2 x0 y1.0215 i0 j-1.0215 z-.170
are redefined as the previous value shifted by the amount specified in this line i.e., the new X is the old X(0) + 0 = 0, the new Y is the old Y(1.0215) + 1.0215 = 2.0430 and the new Z is the old Z(0) -.170 = -.170. Thus in absolute mode the line now means
g2 x0 y2.043 i0 j-1.0215 z-.170.
The start point is still X0, Y1.0215 (from the preceding lines) but now the end point has changed to X0, Y2.0430 thus the error message that the start and end radius doesn’t agree. The I and J modes are handled differently. They aren’t affected by G90 or G91. Their mode is set independently in Config / General Config and will normally be set to Inc. That’s why just changing the Y1.0215 to Y0 fixes the problem in that line. It no longer changes the end point, still retains the same radius but allows the Z to increment as intended.
HTH,
Al
and the rotary table has a 72:1 gear ratio or 5 deg/step (360/72). So for single stepping that would be 200/5 = 40 steps/deg. Multiply the 40 times the micro stepping jumper setting on the Xylotex board, e.g. if it’s set to 8 then 40 X 8 = 320 steps per deg for the Mach3 entry. The velocity and accel numerical values will likely be drastically different from your X, Y and Z due to the deg/min units. Presumably your linear axes are already set-up so here is what I would do. Open the spreadsheet at this link:
.