Chris Morley wrote: > > I bet there is a following error spike right when you do reversal or maybe > not badly because the > spindle does not react with infinite jerk either. > Yes, and that''s why you want to control the rate of spindle reversal so the following axis has a better change of keeping up. > So if your tap reversal changes direction faster then the machine can react, > it doesn't matter > if you have jerk limiting or not - there will be error. > I bet we'd b surprised how much error rigid tapping can tolerate. machine and > part flex is forgiving. > > And that is what I am saying, without jerk limiting, we are asking the > machine to move faster > then it actually can, so we get a small following error spike, most > pronounced at reversals. > So, for rigid tapping, you want the spindle to reverse more gradually than it might be capable of doing. Then, the jerk is reduced. > I remember the graphs I looked at were when the mill cut circles - there were > reversal spikes at each of the four quadrants. > A tight servo should have no spikes at the reversals. The arc interpolation is quite gradual at these reversals, unless the system is trying to do backlash compensation (which I consider to be a big mistake.)
Jon ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
