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G-Code, CAD, and CAM discussions / G12 Trouble...
« on: September 30, 2013, 07:30:58 AM »
Hello - I am struggling to make a small circle using G12.
The code:
makes a line, not a circle - 3/16" line along X only. It is not only that it cuts only a line, but in the toolpath display, only a line is shown. The Y axis simply does not get moved.
I have restarted the computer, and it is highly repeatable for me.
The code
creates a circle, as expected. Note the only change is to shift the X axis by .0002" It also works to move the Y axis by .0002". It appears this problem shows up in very specific x,y positions. Unfortunately, this snippet is part of a larger program which triggers this behavior in about 40% of the holes.
I found a couple previous threads:
http://www.machsupport.com/forum/index.php/topic,23272.0.html has no resolution.
http://www.machsupport.com/forum/index.php/topic,9850.0.html solves his problem with scaling - I am not sure how I would use scaling in my program, but I could imagine that tweaking the scaling would change the x,y positions enough to avoid the issue.
I am attaching a photo of Mach3 running the combined code:
As you can (hoipefully) see, the toolpath display has a large circle with a highlighted line running from the center of the circle to the right edge.
In the next photo, the only change is that I commented out the second G0 line. There is no circle, just a short line (and it is all very small). The toolpath displays are accurate in terms of what my machine actually does, but not in terms of what the GCode seems to be asking for.
Any thoughts as to a) why this is happening or b) how I can avoid it?
Thanks!
Bart
The code:
Code: [Select]
g0 x.8622 y.8207
g12 h.125 i.078125 f10
makes a line, not a circle - 3/16" line along X only. It is not only that it cuts only a line, but in the toolpath display, only a line is shown. The Y axis simply does not get moved.
I have restarted the computer, and it is highly repeatable for me.
The code
Code: [Select]
g0 x.8624 y.8207
g12 h.125 i.078125 f10
creates a circle, as expected. Note the only change is to shift the X axis by .0002" It also works to move the Y axis by .0002". It appears this problem shows up in very specific x,y positions. Unfortunately, this snippet is part of a larger program which triggers this behavior in about 40% of the holes.
I found a couple previous threads:
http://www.machsupport.com/forum/index.php/topic,23272.0.html has no resolution.
http://www.machsupport.com/forum/index.php/topic,9850.0.html solves his problem with scaling - I am not sure how I would use scaling in my program, but I could imagine that tweaking the scaling would change the x,y positions enough to avoid the issue.
I am attaching a photo of Mach3 running the combined code:
Code: [Select]
g0 x.8622 y.8207
g12 h.125 i.078125 f10
g0 x.8624 y.8207
g12 h.125 i.078125 f10
As you can (hoipefully) see, the toolpath display has a large circle with a highlighted line running from the center of the circle to the right edge.
In the next photo, the only change is that I commented out the second G0 line. There is no circle, just a short line (and it is all very small). The toolpath displays are accurate in terms of what my machine actually does, but not in terms of what the GCode seems to be asking for.
Any thoughts as to a) why this is happening or b) how I can avoid it?
Thanks!
Bart