Greetings Peter; In getting a decent rapids w/o following error, I wound up with all the pid.Pgains at 2000, and while I played with the FF2 setting, couldn't detect that is was affecting anything I'm smart enough to detect.
However, after a move of one of the axis's I can hear a faint tone at the servo-thread frequency from the motors. Firing up halscope and looking at the x,y,x outputs, when its singing I can see this tone at all the pid.outputs, at from 15 to 50 milivolts peak to peak. Move an axis a couple thou and it may stop. However, when its doing it, the z, being tasked with supporting the weight of the head, can be seen to move, perhaps as much as 5 thou in a minute or less. I have twice added half a microsecond to the dirsetup and dirhold settings, and a quarter to the step widths which seems to have helped. This particular driver is a DM860 since thats a nema34 motor, running on 60 volts. And 60 is NOT enough for that high of an inductance motor. 120 would be about right, and should put its speeds up there with the 450 oz x&y motors, but no one makes a stepper driver rated for that high a voltage. The DM860 is also noisey as can be as it switches from the microstep chosen to lower values as the speeds requested rises. 3IPM is silent, 30 IPM positively howls, its like a 16 speed road ranger truck transmission, taking the engine thru its optimum power rpm range from the traffic light till its out of sight and hearing. So my guess is that the oscillation may be confusing its internal gearshift. What has been the pulse timing settings a DM860 needs in your experience, and is there something in the pid settings that will dampen that 1 kiloihertz oscillation out, without lowering the Pgain, which seems to be required to get any real rapids speeds above 20 ipm. Clues will be gleefully applied at this point. Thanks Peter. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
