why does G28 or "autohome" set x135 y139 ?
Posted: Wed Nov 02, 2016 9:13 pm
I have read every post in forums on G28, autobedleving, NPN probes, etc.
I have a probe: LJ12A3-4-Z/BX Inductive Proximity Sensor Switch NPN DC6-36V
I have changed only four lines in configuration.h:
1.) line 563 steppers are 160, 160, 5120, 186 --(because I installed the 1/32 stepper drivers. I set the voltages, too)
2.) line 325 Z min endstop set to TRUE -- because I have a NPN inductive sensor with voltage divide. . Three wires : (1) Z endstop
common, (2) endstop signal and (3) heater power for 12 volts.
(homing works well until I change line 435)
3.) line 435 -- uncomment //enable auto bed leveling -- because I want to use autobedleving
Then autohome (G28 from Repetier or "autohome" from the control box) sets x 135 y 139 when the carriage returns to the home position.
#define X_PROBE_OFFSET_FROM_EXTRUDER -25 -- Probe on: -left +right
#define Y_PROBE_OFFSET_FROM_EXTRUDER -29 -- Probe on: -front +behind
If I change line 48:
4.) line 483 Z offsets [-33, -48 , -3] -- my probe is to the left and in front of the nozzle
#define X_PROBE_OFFSET_FROM_EXTRUDER -33 -- Probe on: -left +right
#define Y_PROBE_OFFSET_FROM_EXTRUDER -48 -- Probe on: -front +behind
then the coordinates will be x143 y158 when the carriage is homed the first time.
If I try to move X axis to anything less than x143 it bumps into the stop and makes ugly noises until I power down. If I move to x153 (g1 x153 from Repetier or "move axis X 10mm" from the control box) then the carriage moves to x10 in reality.
Why does G28 change my homing coordinates? It appears to add safe homing + z probe offset to get these values.
G29 does this:
06:40:35.666 : G29 Auto Bed Leveling
06:40:35.749 : Eqn coefficients: a: -0.00000063 b: 0.00000195 d: 0.00001922
06:40:35.752 : planeNormal x: 0.000001 y: -0.000002 z: 1.000000
06:40:35.752 :
06:40:35.754 : Bed Level Correction Matrix:
06:40:35.756 : +1.000000 +0.000000 -0.000001
06:40:35.758 : +0.000000 +1.000000 +0.000002
06:40:35.760 : +0.000001 -0.000002 +1.000000
but G29 does not move the carriage 1 mm. even if I try G92 x0 y0 z0 after G28.
When I comment out define safe_homing the carriage starts to home at the current position x,y but it moves about x-10 y-10 and then homes Z
I have repeatedly loaded unmodified pi3a pro firmware and done only one line change at a time with the same results.
I have a probe: LJ12A3-4-Z/BX Inductive Proximity Sensor Switch NPN DC6-36V
I have changed only four lines in configuration.h:
1.) line 563 steppers are 160, 160, 5120, 186 --(because I installed the 1/32 stepper drivers. I set the voltages, too)
2.) line 325 Z min endstop set to TRUE -- because I have a NPN inductive sensor with voltage divide. . Three wires : (1) Z endstop
common, (2) endstop signal and (3) heater power for 12 volts.
(homing works well until I change line 435)
3.) line 435 -- uncomment //enable auto bed leveling -- because I want to use autobedleving
Then autohome (G28 from Repetier or "autohome" from the control box) sets x 135 y 139 when the carriage returns to the home position.
#define X_PROBE_OFFSET_FROM_EXTRUDER -25 -- Probe on: -left +right
#define Y_PROBE_OFFSET_FROM_EXTRUDER -29 -- Probe on: -front +behind
If I change line 48:
4.) line 483 Z offsets [-33, -48 , -3] -- my probe is to the left and in front of the nozzle
#define X_PROBE_OFFSET_FROM_EXTRUDER -33 -- Probe on: -left +right
#define Y_PROBE_OFFSET_FROM_EXTRUDER -48 -- Probe on: -front +behind
then the coordinates will be x143 y158 when the carriage is homed the first time.
If I try to move X axis to anything less than x143 it bumps into the stop and makes ugly noises until I power down. If I move to x153 (g1 x153 from Repetier or "move axis X 10mm" from the control box) then the carriage moves to x10 in reality.
Why does G28 change my homing coordinates? It appears to add safe homing + z probe offset to get these values.
G29 does this:
06:40:35.666 : G29 Auto Bed Leveling
06:40:35.749 : Eqn coefficients: a: -0.00000063 b: 0.00000195 d: 0.00001922
06:40:35.752 : planeNormal x: 0.000001 y: -0.000002 z: 1.000000
06:40:35.752 :
06:40:35.754 : Bed Level Correction Matrix:
06:40:35.756 : +1.000000 +0.000000 -0.000001
06:40:35.758 : +0.000000 +1.000000 +0.000002
06:40:35.760 : +0.000001 -0.000002 +1.000000
but G29 does not move the carriage 1 mm. even if I try G92 x0 y0 z0 after G28.
When I comment out define safe_homing the carriage starts to home at the current position x,y but it moves about x-10 y-10 and then homes Z
I have repeatedly loaded unmodified pi3a pro firmware and done only one line change at a time with the same results.