darcys...@gmail.com wrote: > Hi all, > > I am experiencing some odd direction changes on a home-brew CNC > machine that I have on loan. > The machine was apparently purchased off ebay, and all the settings I > dug out from data sheets for the driver chips and motors. > > X and Y are working well, but Z (which has a similarly spec'ed but > different motor from the other two) decides to change direction at > random. > The basic behavior is that when you push the jog button in a certain > direction you don't know which direction it will go There could be a problem in the direction signal from the computer to the stepper driver. You should be able to observe this with even a voltmeter, as it only changes when you change direction.
But, I'm taking a bit of a wild guess and thinking that you are only driving ONE of the motor's two phases. It could be a bad driver or motor, but also could very easily be a bad connection between them. So, I'd check the wires carefully. If that doesn't show anything, then I'd check the voltage across the coils with a voltmeter. There should be some voltage across the coils any time the driver is on. If it is a bipolar driver, then it is simple. If a unipolar, then you have to check that half of the coil that is currently being driven. If you get no voltage across the coil, the driver is suspect. If you have voltage across the winding, then ohm out the motor's coils, as it could be an open coil. Jon ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
