On Feb 3 2013 3:08 PM, John Kasunich wrote: > On Sun, Feb 3, 2013, at 03:59 PM, EBo wrote: > >> >> possibly, but a more principled hack would be to interface it at the >> point where it calls the low lever Catmull-Rom spline, and just >> evaluate >> it in reverse. I do not know how difficult that would be, but it >> would >> require the ability to move in the negitive direction. I have >> written >> things like this for moving along splines with custom code, but I >> would >> have to look into how to do this in EMC-s low level motion planning. >> Probably the easiest thing to do would be to set up a >> "reverse-motion" >> pin in HAL, and then evaluate it internally, or modify the adaptive >> move >> command to allow positive/negitive feedback voltage which would >> imply >> forward/reverse of motion. Anyway that is my thought off the cuff. >> > > Where things get ugly is when you try to do this in a general way. > For > example, what happens if you ask for negative feed while in a spindle > synchronized move (single-point threading or rigid tapping)? > Actually, > that issue must have already been dealt with - adaptive feed would > cause the problems in that case even for positive scale factors. But > that was just an example. What about probing moves? What about > the blend between successive non-co-linear straight lines? What > about > a profile that consists of many 0.002" long lines? Can you back up > more than 0.002"? > > Sure, you can say "an EDM will never make a spindle synchronized > move", but changes to the motion module need to do sane things > regardless of what kind of a machine is being controlled.
I was not saying that it could only go back a single move alone a single spline. I just said it needed to be reversible. I will have o think about the spindle-synchronization as I may need that exact functionality to make certain parts. ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_jan _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
