Problem: Pulloff_mm not added to Machine Position after homing

Quintenluyten commented 1 week ago

Wiki Search Terms

homing pulloff_mm mpos_mm "homing and limit switches" "limit switch and homing setup flowchart"

Controller Board

Fysetc E4

Machine Description

I am building a custom 4 axis hot wire cutter. I am currently testing with 4 linear Cartesian axes, every axis has its own limit switch. So the machine has a XY gantry, and a AZ gatry. Once this homing issue is fixed, I will convert the kinematics to 2 makerbot gantries. image_2024-11-13_121842367 image_2024-11-13_121850433

Input Circuits

No response

Configuration file

name: EleksLaser with Fysetc E4 controller
board: Fysetc E4
stepping:
  engine: RMT
  idle_ms: 250
  dir_delay_us: 1
  pulse_us: 2
  disable_delay_us: 0
kinematics: {}
uart1:
  txd_pin: gpio.22
  rxd_pin: gpio.21
  rts_pin: NO_PIN
  cts_pin: NO_PIN
  baud: 115200
  mode: 8N1
axes:
  shared_stepper_disable_pin: gpio.25
  x:
    steps_per_mm: 100
    max_rate_mm_per_min: 500
    acceleration_mm_per_sec2: 50
    max_travel_mm: 290
    soft_limits: true
    homing:
      cycle: 1
      positive_direction: false
      mpos_mm: 0
      feed_mm_per_min: 200
      seek_mm_per_min: 500
      settle_ms: 500
      seek_scaler: 1.1
      feed_scaler: 1.1
    motor0:
      limit_neg_pin: gpio.34:low
      hard_limits: false
      pulloff_mm: 3
      tmc_2209:
        uart_num: 1
        addr: 1
        r_sense_ohms: 0.11
        run_amps: 1
        homing_amps: 1
        hold_amps: 0.5
        microsteps: 16
        stallguard: 0
        stallguard_debug: false
        toff_disable: 0
        toff_stealthchop: 5
        toff_coolstep: 3
        run_mode: CoolStep
        homing_mode: CoolStep
        use_enable: false
        step_pin: gpio.27
        direction_pin: gpio.26
        disable_pin: NO_PIN
      limit_pos_pin: NO_PIN
      limit_all_pin: NO_PIN
  y:
    steps_per_mm: 100
    max_rate_mm_per_min: 500
    acceleration_mm_per_sec2: 50
    max_travel_mm: 150
    soft_limits: true
    homing:
      cycle: 2
      positive_direction: false
      mpos_mm: 0
      feed_mm_per_min: 200
      seek_mm_per_min: 500
      settle_ms: 500
      seek_scaler: 1.1
      feed_scaler: 1.1
    motor0:
      limit_neg_pin: gpio.35:low
      hard_limits: false
      pulloff_mm: 3
      tmc_2209:
        uart_num: 1
        addr: 3
        r_sense_ohms: 0.11
        run_amps: 1
        homing_amps: 1
        hold_amps: 0.5
        microsteps: 16
        stallguard: 0
        stallguard_debug: false
        toff_disable: 0
        toff_stealthchop: 5
        toff_coolstep: 3
        run_mode: CoolStep
        homing_mode: CoolStep
        use_enable: false
        step_pin: gpio.33
        direction_pin: gpio.32
        disable_pin: NO_PIN
      limit_pos_pin: NO_PIN
      limit_all_pin: NO_PIN
  z:
    steps_per_mm: 100
    max_rate_mm_per_min: 500
    acceleration_mm_per_sec2: 50
    max_travel_mm: 150
    soft_limits: true
    homing:
      cycle: 2
      positive_direction: false
      mpos_mm: 0
      feed_mm_per_min: 200
      seek_mm_per_min: 500
      settle_ms: 500
      seek_scaler: 1.1
      feed_scaler: 1.1
    motor0:
      limit_neg_pin: gpio.15:low
      hard_limits: false
      pulloff_mm: 3
      tmc_2209:
        uart_num: 1
        addr: 0
        r_sense_ohms: 0.11
        run_amps: 1
        homing_amps: 1
        hold_amps: 0.5
        microsteps: 16
        stallguard: 0
        stallguard_debug: false
        toff_disable: 0
        toff_stealthchop: 5
        toff_coolstep: 3
        run_mode: CoolStep
        homing_mode: CoolStep
        use_enable: false
        step_pin: gpio.16
        direction_pin: gpio.17:low
        disable_pin: NO_PIN
      limit_pos_pin: NO_PIN
      limit_all_pin: NO_PIN
  a:
    steps_per_mm: 100
    max_rate_mm_per_min: 500
    acceleration_mm_per_sec2: 50
    max_travel_mm: 290
    soft_limits: true
    homing:
      cycle: 1
      positive_direction: false
      mpos_mm: 0
      feed_mm_per_min: 200
      seek_mm_per_min: 500
      settle_ms: 500
      seek_scaler: 1.1
      feed_scaler: 1.1
    motor0:
      limit_neg_pin: gpio.36:low
      hard_limits: false
      pulloff_mm: 3
      tmc_2209:
        uart_num: 1
        addr: 2
        r_sense_ohms: 0.11
        run_amps: 1
        homing_amps: 1
        hold_amps: 0.5
        microsteps: 16
        stallguard: 0
        stallguard_debug: false
        toff_disable: 0
        toff_stealthchop: 5
        toff_coolstep: 3
        run_mode: CoolStep
        homing_mode: CoolStep
        use_enable: false
        step_pin: gpio.14
        direction_pin: gpio.12:low
        disable_pin: NO_PIN
      limit_pos_pin: NO_PIN
      limit_all_pin: NO_PIN

spi:
  miso_pin: gpio.19
  mosi_pin: gpio.23
  sck_pin: gpio.18
sdcard:
  cs_pin: gpio.5
  card_detect_pin: NO_PIN
start:
  must_home: true
  deactivate_parking: false
  check_limits: false
PWM:
  output_pin: gpio.2

Startup Messages

$G
[GC:G0 G54 G17 G21 G90 G94 M5 M9 T0 F0 S0]
ok
$SS
<Alarm|MPos:0.000,0.000,0.000,0.000|FS:0,0|WCO:0.000,0.000,70.000,30.000>
[MSG:INFO: FluidNC v3.0.x (noGit)  (noGit)]
[MSG:INFO: Compiled with ESP32 SDK:v4.4.7-dirty]
[MSG:INFO: Local filesystem type is littlefs]
[MSG:INFO: Configuration file:config.yml]
[MSG:INFO: Machine EleksLaser with Fysetc E4 controller]
[MSG:INFO: Board Fysetc E4]
[MSG:INFO: UART1 Tx:gpio.22 Rx:gpio.21 RTS:NO_PIN Baud:115200]
[MSG:INFO: SPI SCK:gpio.18 MOSI:gpio.23 MISO:gpio.19]
[MSG:INFO: SD Card cs_pin:gpio.5 detect:NO_PIN freq:8000000]
[MSG:INFO: Stepping:RMT Pulse:2us Dsbl Delay:0us Dir Delay:1us Idle Delay:250ms]
[MSG:INFO: Axis count 4]
[MSG:INFO: Shared stepper disable gpio.25]
[MSG:INFO: Axis X (0.000,290.000)]
[MSG:INFO:   Motor0]
[MSG:INFO:     tmc_2209 UART1 Addr:1 CS:NO_PIN Step:gpio.27 Dir:gpio.26 Disable:NO_PIN R:0.110]
[MSG:INFO:  X Neg Limit gpio.34:low]
[MSG:INFO: Axis Y (0.000,150.000)]
[MSG:INFO:   Motor0]
[MSG:INFO:     tmc_2209 UART1 Addr:3 CS:NO_PIN Step:gpio.33 Dir:gpio.32 Disable:NO_PIN R:0.110]
[MSG:INFO:  Y Neg Limit gpio.35:low]
[MSG:INFO: Axis Z (0.000,150.000)]
[MSG:INFO:   Motor0]
[MSG:INFO:     tmc_2209 UART1 Addr:0 CS:NO_PIN Step:gpio.16 Dir:gpio.17:low Disable:NO_PIN R:0.110]
[MSG:INFO:  Z Neg Limit gpio.15:low]
[MSG:INFO: Axis A (0.000,290.000)]
[MSG:INFO:   Motor0]
[MSG:INFO:     tmc_2209 UART1 Addr:2 CS:NO_PIN Step:gpio.14 Dir:gpio.12:low Disable:NO_PIN R:0.110]
[MSG:INFO:  A Neg Limit gpio.36:low]
[MSG:INFO: X Axis driver test passed]
[MSG:INFO: Y Axis driver test passed]
[MSG:INFO: Z Axis driver test passed]
[MSG:INFO: A Axis driver test passed]
[MSG:INFO: Kinematic system: Cartesian]
[MSG:INFO: Connecting to STA SSID:EC-net-Guest]
[MSG:INFO: Connecting.]
[MSG:INFO: Connecting..]
[MSG:INFO: Connected - IP is 192.168.0.191]
[MSG:INFO: WiFi on]
[MSG:INFO: Start mDNS with hostname:http://fluidnc.local/]
[MSG:INFO: HTTP started on port 80]
[MSG:INFO: Telnet started on port 23]
[MSG:INFO: PWM Spindle Ena:NO_PIN Out:gpio.2 Dir:NO_PIN Freq:5000Hz Period:8191]
ok
<Alarm|MPos:0.000,0.000,0.000,0.000|FS:0,0|Ov:100,100,100>
$H
[MSG:Homed:XA]
[MSG:Homed:YZ]
ok
<Idle|MPos:0.000,0.000,0.000,0.000|FS:0,0>

User Interface Software

WebUI

What happened?

Expected behavior: After homing, I expect the MPos to be set to "MPos:3.000,3.000,3.000,3.000" since the machine homes at (0,0,0,0), and has a pulloff distance of 3 mm.

Observed behavior: However, the machine sets the machine position to "MPos:0.000,0.000,0.000,0.000" after the homing routine (including pulloff) is done. So now the limit switches are at (-3,-3,-3,-3) and out of reach of the soft limits of the machine.

Other thing I tried: If I set the mpos_mm of each axis to 3 mm, then the soft limits limit movement to (3 mm, max_travel_mm + 3 mm). However, I want the travel to be limited to (0 mm, max_travel_mm), with 0 mm being the limit switch location. Therefore, the pulloff distance needs to be used to set the machine position after the homing routine.

Why the expected behavior should make sense: The following page indicates that my expected behavior is what fluidnc should do, but I do not observe it in practice: http://wiki.fluidnc.com/en/support/machine_space_and_homing

GCode File

No response

Other Information

No response

MitchBradley commented 1 week ago

The wiki was misleading and inconsistent. I edited it to reflect the intended behavior, which FluidNC implements correctly. After homing, mpos_mm is set to one end of the travel range. pulloff_mm is a guard zone that is outside the travel range. When soft limits are enabled, you can travel all the way to mpos_mm without consideration of pulloff_mm

Quintenluyten commented 1 week ago

Would there be any way to allow the machine to travel past mpos_mm in to the guard zone when soft limits are enabled? My situation is similar to how a 3D printer bed works: the machine needs to be able to move all the way up to the limit switch during operation, and the limit switch cannot be placed further down the axis, since this would cause a collision.

In a 3D printer, this is needed since the nozzle needs to be able to get very close to the bed during normal operation. For my machine, I would like my cutting tool to cut very close to the CNC table.

One alternative is homing away from the table, but this will be less accurate

MitchBradley commented 1 week ago

Can you put the Z homing switch on the end away from the bed, and use the probe function to reference to the bed? Or not home Z at all but rather just probe that axis?

bdring / FluidNC