Homing in Z setting strange value?

Hey Everyone,

Wanted to see if anyone could explain to me why when my machine homes in Z it sets the home position to positive 2"?

I got my X and Y working fine, but I cant seem to figure this out
My .INI is below

---

# If you make changes to this file, they will be
# overwritten when you run PNCconf again

[EMC]
MACHINE = TC225
DEBUG = 0
VERSION = 1.1

[DISPLAY]
DISPLAY = axis
POSITION_OFFSET = RELATIVE
POSITION_FEEDBACK = ACTUAL
MAX_FEED_OVERRIDE = 2.000000
MAX_SPINDLE_OVERRIDE = 1.000000
MIN_SPINDLE_OVERRIDE = 0.500000
INTRO_GRAPHIC = linuxcnc.gif
INTRO_TIME = 5
PROGRAM_PREFIX = /home/tc225/linuxcnc/nc_files
INCREMENTS = .1in .05in .01in .005in .001in .0005in .0001in
POSITION_FEEDBACK = ACTUAL
DEFAULT_LINEAR_VELOCITY = 0.250000
MAX_LINEAR_VELOCITY = 20.000000
MIN_LINEAR_VELOCITY = 0.016667
DEFAULT_ANGULAR_VELOCITY = 12.000000
MAX_ANGULAR_VELOCITY = 180.000000
MIN_ANGULAR_VELOCITY = 1.666667
EDITOR = gedit
GEOMETRY = xyz

[FILTER]
PROGRAM_EXTENSION = .png,.gif,.jpg Greyscale Depth Image
PROGRAM_EXTENSION = .py Python Script
png = image-to-gcode
gif = image-to-gcode
jpg = image-to-gcode
py = python

[TASK]
TASK = milltask
CYCLE_TIME = 0.010

[RS274NGC]
PARAMETER_FILE = linuxcnc.var

[EMCMOT]
EMCMOT = motmod
COMM_TIMEOUT = 1.0
SERVO_PERIOD = 1000000

[HOSTMOT2]
# **** This is for info only ****
# DRIVER0=hm2_eth
# BOARD0=7i76e

[HAL]
HALUI = halui
HALFILE = TC225.hal
HALFILE = custom.hal
POSTGUI_HALFILE = postgui_call_list.hal
SHUTDOWN = shutdown.hal

[HALUI]

[KINS]
JOINTS = 3
KINEMATICS = trivkins coordinates=XYZ

[TRAJ]
COORDINATES = XYZ
LINEAR_UNITS = inch
ANGULAR_UNITS = degree
DEFAULT_LINEAR_VELOCITY = 2.00
MAX_LINEAR_VELOCITY = 20.00

[EMCIO]
EMCIO = io
CYCLE_TIME = 0.100
TOOL_TABLE = tool.tbl

#******************************************
[AXIS_X]
MAX_VELOCITY = 3.33333333333
MAX_ACCELERATION = 30.0
MIN_LIMIT = -15.0
MAX_LIMIT = 0.0

[JOINT_0]
TYPE = LINEAR
HOME = 0.0
FERROR = 0.5
MIN_FERROR = 0.05
MAX_VELOCITY = 3.33333333333
MAX_ACCELERATION = 30.0
# The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION
# If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger.
STEPGEN_MAXVEL = 4.17
STEPGEN_MAXACCEL = 37.50
P = 1000.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
# these are in nanoseconds
DIRSETUP = 10000
DIRHOLD = 10000
STEPLEN = 5000
STEPSPACE = 5000
STEP_SCALE = -50800.102
MIN_LIMIT = -15.0
MAX_LIMIT = 0.0
HOME_OFFSET = -1.5
HOME_SEARCH_VEL = 0.050000
HOME_LATCH_VEL = 0.016667
HOME_FINAL_VEL = 1.0
HOME_USE_INDEX = NO
HOME_SEQUENCE = 1
#******************************************

#******************************************
[AXIS_Y]
MAX_VELOCITY = 20.0
MAX_ACCELERATION = 50.0
MIN_LIMIT = -10.0
MAX_LIMIT = 0.0

[JOINT_1]
TYPE = LINEAR
HOME = 0.0
FERROR = 0.5
MIN_FERROR = 0.05
MAX_VELOCITY = 20.0
MAX_ACCELERATION = 50.0
# The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION
# If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger.
STEPGEN_MAXVEL = 25.00
STEPGEN_MAXACCEL = 62.50
P = 1000.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
# these are in nanoseconds
DIRSETUP = 5000
DIRHOLD = 5000
STEPLEN = 5000
STEPSPACE = 5000
STEP_SCALE = 50800.102
MIN_LIMIT = -10.0
MAX_LIMIT = 0.0
HOME_OFFSET = -1.5
HOME_SEARCH_VEL = 0.050000
HOME_LATCH_VEL = 0.016667
HOME_FINAL_VEL = 1.0
HOME_USE_INDEX = NO
HOME_SEQUENCE = 2
#******************************************

#******************************************
[AXIS_Z]
MAX_VELOCITY = 1.0
MAX_ACCELERATION = 30.0
MIN_LIMIT = -7.75
MAX_LIMIT = 7.75

[JOINT_2]
TYPE = LINEAR
HOME = 0.0
FERROR = 0.5
MIN_FERROR = 0.05
MAX_VELOCITY = 1.0
MAX_ACCELERATION = 30.0
# The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION
# If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger.
STEPGEN_MAXVEL = 1.25
STEPGEN_MAXACCEL = 37.50
P = 1000.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
# these are in nanoseconds
DIRSETUP = 10000
DIRHOLD = 10000
STEPLEN = 5000
STEPSPACE = 5000
STEP_SCALE = -50800.102
MIN_LIMIT = -7.75
MAX_LIMIT = 7.75
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = 0.050000
HOME_LATCH_VEL = 0.016667
HOME_FINAL_VEL = 1.0
HOME_USE_INDEX = NO
HOME_SEQUENCE = 0
#******************************************

[SPINDLE_9]
P = 0
I = 0
D = 0
FF0 = 1
FF1 = 0
FF2 = 0
BIAS = 0
DEADBAND = 0
MAX_OUTPUT = 2000




Thanks for any info!

hi
the HOME is never ZERO its the position the mashine ends at the end of the homing sequence
so if your switch is at the TOP as it shoudt be
WHY do you got 50000 STEPS per inch

[AXIS_Z]
MAX_VELOCITY = 1.0
MAX_ACCELERATION = 30.0
#max traveling Z is the NEG MIN
MIN_LIMIT = -7.75
MAX_LIMIT = 0.05

[JOINT_2]
TYPE = LINEAR
HOME = -0.1
FERROR = 0.5
MIN_FERROR = 0.05
MAX_VELOCITY = 4.0
MAX_ACCELERATION = 30.0
# The values below should be 25% larger than MAX_VELOCITY and MAX_ACCELERATION
# If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger.
#STEPGEN_MAXVEL = 1.25
STEPGEN_MAXACCEL = 37.50
P = 1000.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
# these are in nanoseconds
DIRSETUP = 20000
DIRHOLD = 10000
STEPLEN = 5000
STEPSPACE = 5000
STEP_SCALE = -50800.102
MIN_LIMIT = -7.75
MAX_LIMIT = 0.05
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = 0.10
HOME_LATCH_VEL = 0.05
HOME_FINAL_VEL = 1.0
HOME_USE_INDEX = NO
HOME_SEQUENCE = 0

pl7i92,

My home switch is in the dead center of the travel of my z axis.

AS far as the steps per inch are you refering to STEP_SCALE = -50800.102?

If so that is what was calculated and is working on my machine, dose it seem wrong?

I guess what im having trouble with on Z is understanding where the 2.00 value is being generated from.

What I did on X and y is left my home_offset and home at 0 initially. Ran my homing cycle. from there I could jog the machine and watch the readout to determine what the travel was to move from the home switch to .25 short of the +LS then used that as my HOME_OFFSET to set my home as The end of my soft limit and left HOME at 0 so it positioned the table there.

As my .INI sits right now it seems to me it should come up and find home then set that home position as zero so as home is triggered my machine poisition should be zero not 2.00. that what I dont understand.

hope that makes some sense.

So you are confused by the fact that your DRO says 2 when at the home position.

Do you have a G54 work coordinate offset set? (Perhaps you have an offset of 2 there.)

Todd,

From my understanding and what I saw setting up the homing on the X and Y, That with HOME=0 and HOME_OFFSET=0 the machine should find the home switch and at latching the it should set its current location as that joints 0 position. since HOME=0 the machine should not move from that position (It stays in place in real life as expected) The thing I cant understand is where the 2.00 in the machine coordinates is coming from. Last night I tried changing HOME_OFFSET=1.0 ... That resulted in homing then moving 1.0" from the home latch position, but the machine coordinates still reported Z at 2.0"

Ill double check the work offset, but shouldn't the machine coordinate be independent of an offset? That is a position based off the Machine Coords. not the other way around.

Im sure I'm just missing something stupid but I cant quite figure it out.

Yes the machine coordinates are independent of work coordinates, but the DRO shows the work coordinates.

My DRO shows both the work and machine coords

Sometimes when configuring a new machine LInuxcnc gets confused here. various variables are stored in a file in your config folder between sessions. Usually it has a .var extension but that can be overridden in your ini file. A simple solution is to close LinuxCNC, delete this file and restart.

agree to rod delete all VAR bak.var Files of your mashine folder to get a clear var file at the start
of testing