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General Mach Discussion / ugly circles
« on: July 07, 2006, 08:22:53 PM »
I am having a hard time cutting accurate circles. when I cut them they are slightly elliptical it seems that there the motors are not moving at the correct rates. At the points where the x axis is acceleration that quadrant of the circle is skewed away from the x axis. As x is decelerating it flattens out that quadrant of the circle. this problem is repeatable each and every time. If I reverse the cutting path the problem is exactly the same.
I have a taig mill with a xylotex board. If I run a program the spindle will return to the home position with absolutely no error on the dial indicator, so it is safe to say that I am not losing steps.
I have tried different bit sizes and speeds to eliminate the possibility of bit flex. All gibs are very tight with no play. I have the axis weighted via a pulley system so there is no backlash.
I have run g code generated from mastercam as well as the wizards included with mach2, both sadly produce the same results. I have tried both constant velocity and exact stop with no change in the outcome.
There is one question that may answer my dilema. If I use exact stop when cutting a circle does the stop occur at the points indicated in the g code or does the mach software compute each individual stop point?
I have a taig mill with a xylotex board. If I run a program the spindle will return to the home position with absolutely no error on the dial indicator, so it is safe to say that I am not losing steps.
I have tried different bit sizes and speeds to eliminate the possibility of bit flex. All gibs are very tight with no play. I have the axis weighted via a pulley system so there is no backlash.
I have run g code generated from mastercam as well as the wizards included with mach2, both sadly produce the same results. I have tried both constant velocity and exact stop with no change in the outcome.
There is one question that may answer my dilema. If I use exact stop when cutting a circle does the stop occur at the points indicated in the g code or does the mach software compute each individual stop point?