For simple simker EDM I implemented reversing in a gcode loop sensing an analog input:
http://code.google.com/p/sector67-sandbox/wiki/FrequencyBasedAnalogInput this was simple for my application, could stand to be refined somewhat, and would get complicated for anything but straight down/up. Scott On Sun, Feb 3, 2013 at 7:50 PM, EBo <e...@sandien.com> wrote: > 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 > ------------------------------------------------------------------------------ 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
