I have finally gotten to the point where I am running my bridgeport on Emc2 and have spent time tuning the software parameters to what I thought were optimum. When I home the x and y axis, they home within <.001 in. consistently. I have a DRO to monitor table position. I am running with a max velocity of 1.5 (90) ipm and max acceleration of 2.0. The motors are Superior Electric Slo-Syn 840 oz-in 200 steps per rev with a 2.5 ratio to the ball screw with a pitch of 0.2. This worked out to a scale of 2500. The driver boards accept quadrature signals from the three parallel ports.
However when I run axis.ngc, the ending x and y positions are at variance from the commanded positions and each time I run the program (after first homing), I get different variances. I calculated the variances by subtracting the actual position from the commanded position and x can vary from -.148 to +.009, while y can vary from .063 to .008. I tried reducng the acceleration to 1.0 , reducing max velocity to .75 and changing the cutting rate from 60 to 5 in the ngc program and still no significant improvement. I can't figure out what is causing my setup to behave this way, and wonder if any one has any ideas on this or has come across this behavior before? Here is a portion of the ini file: [EMC] VERSION = $Revision: 1.8.2.3 $ MACHINE = EMC-HAL-STEP-IN NML_FILE = emc.nml DEBUG = 0 [DISPLAY] DISPLAY = axis CYCLE_TIME = 0.200 POSITION_OFFSET = RELATIVE POSITION_FEEDBACK = ACTUAL MAX_FEED_OVERRIDE = 1.2 PROGRAM_PREFIX = /usr/share/emc/ncfiles/ INTRO_GRAPHIC = emc2.gif INTRO_TIME = 5 [TASK] TASK = milltask CYCLE_TIME = 0.010 [RS274NGC] PARAMETER_FILE = stepper.var [EMCMOT] EMCMOT = motmod SHMEM_KEY = 111 COMM_TIMEOUT = 1.0 COMM_WAIT = 0.010 BASE_PERIOD= 50000 SERVO_PERIOD = 1000000 TRAJ_PERIOD = 10000000 [HAL] HALFILE = 1BPstepper.hal HALFILE = 1BPpinout.hal [TRAJ] AXES = 3 COORDINATES = X Y Z HOME = 0 0 0 LINEAR_UNITS = inch ANGULAR_UNITS = degree CYCLE_TIME = 0.010 DEFAULT_VELOCITY = 0.0167 MAX_VELOCITY = 1.5 DEFAULT_ACCELERATION = 15.0 MAX_ACCELERATION = 2.10 [AXIS_0] TYPE = LINEAR HOME = 0.000 MAX_VELOCITY = 1.5 MAX_ACCELERATION = 2.0 STEPGEN_MAXVEL = 1.6 STEPGEN_MAXACCEL = 2.06 BACKLASH = 0.002 INPUT_SCALE = 2500 OUTPUT_SCALE = 1.000 MIN_LIMIT = -13.2 MAX_LIMIT = 13.2 FERROR = 0.050 MIN_FERROR = 0.010 HOME_OFFSET = 13.21 HOME_SEARCH_VEL = 0.8 HOME_LATCH_VEL = 0.05 HOME_USE_INDEX = NO HOME_IGNORE_LIMITS = YES [AXIS_1] TYPE = LINEAR HOME = 0.000 MAX_VELOCITY = 1.5 MAX_ACCELERATION = 2.0 STEPGEN_MAXVEL = 1.6 STEPGEN_MAXACCEL = 2.06 BACKLASH = 0.002 INPUT_SCALE = 2500 OUTPUT_SCALE = 1.000 MIN_LIMIT = -5.69 MAX_LIMIT = 7.0 FERROR = 0.050 MIN_FERROR = 0.010 HOME_OFFSET = 7.7 HOME_SEARCH_VEL = 0.8 HOME_LATCH_VEL = 0.05 HOME_USE_INDEX = NO HOME_IGNORE_LIMITS = YES [AXIS_2] TYPE = LINEAR HOME = 0.0 MAX_VELOCITY = 1.0 MAX_ACCELERATION = 2.0 STEPGEN_MAXVEL = 1.05 STEPGEN_MAXACCEL = 2.06 BACKLASH = 0.000 INPUT_SCALE = 2000 OUTPUT_SCALE = 1.000 MIN_LIMIT = -4.54 MAX_LIMIT = 0.2 FERROR = 0.050 MIN_FERROR = 0.010 HOME_OFFSET = 0.2 HOME_SEARCH_VEL = 0.5 HOME_LATCH_VEL = 0.05 HOME_USE_INDEX = NO HOME_IGNORE_LIMITS = YES [EMCIO] EMCIO = io CYCLE_TIME = 0.100 TOOL_TABLE = stepper.tbl ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
