Ian W. Wright wrote: > 'Scuse me for stepping in but I'm a bit confused by a couple of things > being said in this thread..... > 1. Exactly why does a low accel round corners more than a fast accel.? The program calculates all moves based on the specified machine acceleration in the ini file, and the velocities specified in the G-code. For each move, a point at the end of the move is chosen where deceleration would need to begin to stop at the exact endpoint specified. On machines with higher acceleration limits, that point will be closer to the endpoint than on machines with less accel. available. This point near the end of the move is where the acceleration to the next move in the G-code is blended in. So, at a right-angle corner, with G64 in force, the X axis will actually start moving before the Y axis comes to a complete stop. That will, of course, round your corners. > Does this suggest that a machine with slightly underpowered drive motors > is inherently less precise than one with big drive motors? Yes. > 2. Is there some advantage in using G64 with a tolerance over G61 if you > want tight adherance to a toolpath? Yes, it allows the program to run MUCH faster,while maintaining the required accuracy. I ran some tests a few weeks ago between G64 (no parameter) and G64 P0.0005 (in inches) and the difference was four minutes vs. 17 seconds! This was a 10,000 segment circle 2" in diameter. G61 would certainly be as bad as the G64 with no tolerance, if not even worse.
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