Anycubic Mega SE motor swap

 I was getting Y-axis shifting on my printer even seen an X-axis shift since changing to Klipper.  After swapping out the belts and adding tensioning knobs to both axes, I decided the issue must be the motors.  It wasn't but that is now hindsight.  

I purchased the motors from Amazon.  When I pulled the original motors from the printer, I noticed the cables were not the same as the provided cables I received in the order.  In the image, the wiring on the left are wired straight-through from the controlling board.  The wiring on the right is crossed at the motor (Red-Black-Blue-Green) but aligned straight at the board (Red-Blue-Green-Black).  I swapped the original cables with the new cables. 

 

For the motors, the original has the pulley fused to the post.  I purchased the pulleys (6mm with 20 teeth and 5mm bore) for the new motors.  In the photo below, the original motor is on the left.  The newer motors appear to have a little more power.

After I installed the motors, I did a quick homing process in Klipper and the motors turn in the opposite direction from the original motors.  Klipper makes that an easy fix.  In my printer.cfg file, I changed the dir_pin from !PC5 to PC5 for the x stepper and !PC7 to PC7 for the y stepper.  

I think the new motors look good.  To keep the belt nearest the center of the 2040 rail, I installed the pulley in the direction you see in the photo.  

As for the shifting, it remained after the motor shift.  As of this writing, my fix for the shifting was setting the speeds in Cura slicer to match.  That is, the first layer speed, fill speeds, etc. are each set to the exact same value of 50mm.  I'll probably adjust that number since the quality of the print is a bit rough.  

Hope this helps.

My Anycubic Mega SE Klipper config is here.

Update:

Setting the slicer to a common speed did not fix the shifting in my latest print.  I'm determined to figure this out.

Update:

I was still using the same Cura settings for slicing that I used with the original firmware.  I kept working on the Klipper firmware settings since that was my change.  I believe the shifting issue is attributed to both Klipper and Cura settings.  I've re-leveled the printer to a wider gap than I used before Klipper.  I'm using 1.5mm feeler gauge for leveling.  I've also reduced the flow rate in Cura to be 75%.  Prior to Klipper, the shipping firmware was yielding nice results at 100% flow.  Klipper looks to be yielding really nice results with the reduced flow and gap I have for the bed and nozzle.  My shifting issue seems to be attributed to the nozzle scraping the top of the print.  The wider gap and reduced flow fixed that too.  I'm hopeful this is the fix and Klipper is good to go.  I'm sure I'll keep tinkering with settings to balance the gap and the flow rate.

Anycubic Mega SE firmware

Anycubic Mega SE

Using Klipper and Fluidd

I was receiving a warning message in Octopi concerning the shipping version of the Mega SE firmware.  I contacted Anycubic directly for updated firmware.  This was their response:

"MEGA SE's firmware can only remove the chip to update the firmware

Such an operation is difficult

Generally we do not let customers update firmware"

I also asked Anycubic if they could provide a schematic for the Mega SE and they didn't have one.  Surely someone at Anycubic has one.  

I decided to make a switch to Klipper firmware.  After some internet searches and tests, I've settled on the configuration below.  I'm still tweaking some settings but getting acceptable results.  Make sure you compile Klipper for the ATMega1284P controller.

I printed the Klipper tower to get the pressure advance value.  I also performed an extrusion calibration to set the rotation distance in the extruder section of the config file.  Make sure to run the PID tuning process to get better values for your system.

If you're in the same situation I was with Mega SE firmware, I hope this helps.  I'd like to hear from you if you find better settings.

my printer.cfg

# To use this config, the firmware should be compiled for the

# AVR atmega1284p.

# Anycubic Mega SE (Created 20220326)

# The PCB shows Mega Zero v0.4 on the surface

# The hotend on the tested printer was replaced with a Creality Ender 3 V2 hotend

# Note, a number of Melzi boards are shipped with a bootloader that

# requires the following command to flash the board:

#  avrdude -p atmega1284p -c arduino -b 57600 -P /dev/ttyUSB0 -U out/klipper.elf.hex

# If the above command does not work and "make flash" does not work

# then one may need to flash a bootloader to the board - see the

# Klipper docs/Bootloaders.md file for more information.

# See docs/Config_Reference.md for a description of parameters.

[stepper_x]

step_pin: PD7

dir_pin: !PC5

enable_pin: !PD6

microsteps: 16

rotation_distance: 40

endstop_pin: ^PC2

position_endstop: 0

position_min: 0

position_max: 230

homing_speed: 20

[stepper_y]

step_pin: PC6

dir_pin: !PC7

enable_pin: !PD6

microsteps: 16

rotation_distance: 40

endstop_pin: ^PC3

position_endstop: 0

position_min: 0

position_max: 235

homing_speed: 20

[stepper_z]

step_pin: PB3

dir_pin: PB2

enable_pin: !PA5

microsteps: 16

rotation_distance: 8

endstop_pin: ^PC4

position_endstop: 0.0

position_max: 250

[safe_z_home]

home_xy_position: 10,10

speed: 50

z_hop: 5

z_hop_speed: 20

move_to_previous: false

[extruder]

#  Extruder on the Anycubic Mega SE looks like a BMG clone

step_pin: PB1

dir_pin: PB0

enable_pin: !PD6

microsteps: 16

rotation_distance: 7.403

nozzle_diameter: 0.400

filament_diameter: 1.750

heater_pin: PD5

sensor_type: EPCOS 100K B57560G104F

sensor_pin: PA7

control: pid

min_temp: 0

max_temp: 260

# Used Klipper tuning to get Pressure Advance

pressure_advance = .380

# Tuned for 200 degrees Celsius

pid_Kp=21.488 

pid_Ki=1.291

pid_Kd=89.445

## Added

max_extrude_cross_section = 150

min_extrude_temp = 180

max_extrude_only_distance: 120.0

full_steps_per_rotation: 200

[heater_bed]

heater_pin: PD4

sensor_type: EPCOS 100K B57560G104F

sensor_pin: PA6

control: pid

min_temp: 0

max_temp: 130

# tuned for 60 degrees Celsius

pid_Kp=62.181 

pid_Ki=1.884 

pid_Kd=512.996

[fan]

pin: PB4

[mcu]

serial: /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0

[printer]

kinematics: cartesian

max_velocity: 300

max_accel: 3000

max_z_velocity: 5

max_z_accel: 100

[display]

lcd_type: st7920

cs_pin: PA3

sclk_pin: PA1

sid_pin: PC1

encoder_pins: ^PD2, ^PD3

click_pin: ^!PC0

######################################################################

# Start Print and End Print

######################################################################

# Replace the slicer's custom start and end g-code scripts with

# START_PRINT and END_PRINT.

[gcode_macro START_PRINT]

gcode:

    {% set BED_TEMP = params.BED_TEMP|default(60)|float %}

    {% set EXTRUDER_TEMP = params.EXTRUDER_TEMP|default(190)|float %}

    # Start bed heating

    M140 S{BED_TEMP}

    # Use absolute coordinates

    G90

    # Reset the G-Code Z offset (adjust Z offset if needed)

    SET_GCODE_OFFSET Z=0.0

    # Home the printer

    G28

    # Move the nozzle near the bed

    G1 Z5 F3000

    # Move the nozzle very close to the bed

    G1 Z0.15 F300

    # Wait for bed to reach temperature

    M190 S{BED_TEMP}

    # Set and wait for nozzle to reach temperature

    M109 S{EXTRUDER_TEMP}

[gcode_macro END_PRINT]

gcode:

    # Turn off bed, extruder, and fan

    M140 S0

    M104 S0

    M106 S0

    # Move nozzle away from print while retracting

    G91

    G1 X-2 Y-2 E-3 F300

    # Raise nozzle by 10mm

    G1 Z10 F3000

    G90

    # Disable steppers

    M84

######################################################################

# Beeper

######################################################################

# M300 : Play tone. Beeper support, as commonly found on usual LCD

# displays (i.e. RepRapDiscount 2004 Smart Controller, RepRapDiscount

# 12864 Full Graphic). This defines a custom I/O pin and a custom

# GCODE macro.  Usage:

#   M300 [P<ms>] [S<Hz>]

#   P is the tone duration, S the tone frequency.

# The frequency won't be pitch perfect.

###[output_pin BEEPER_pin]

###pin: ar37

#   Beeper pin. This parameter must be provided.

#   ar37 is the default RAMPS/MKS pin.

###pwm: True

#   A piezo beeper needs a PWM signal, a DC buzzer doesn't.

###value: 0

#   Silent at power on, set to 1 if active low.

###shutdown_value: 0

#   Disable at emergency shutdown (no PWM would be available anyway).

###cycle_time: 0.001

#   Default PWM frequency : 0.001 = 1ms will give a tone of 1kHz

#   Although not pitch perfect.

[virtual_sdcard]

path: ~/gcode_files

[gcode_macro _M300]

gcode:

    # Use a default 1kHz tone if S is omitted.

    {% set S = params.S|default(1000)|int %}

    # Use a 10ms duration is P is omitted.

    {% set P = params.P|default(100)|int %}

    SET_PIN PIN=BEEPER_pin VALUE=0.5 CYCLE_TIME={ 1.0/S if S > 0 else 1 }

    G4 P{P}

    SET_PIN PIN=BEEPER_pin VALUE=0

######################################################################

# Filament Change

######################################################################

# M600: Filament Change. This macro will pause the printer, move the

# tool to the change position, and retract the filament 50mm. Adjust

# the retraction settings for your own extruder. After filament has

# been changed, the print can be resumed from its previous position

# with the "RESUME" gcode.

[pause_resume]

[gcode_macro M600]

gcode:

    {% set X = params.X|default(50)|float %}

    {% set Y = params.Y|default(0)|float %}

    {% set Z = params.Z|default(10)|float %}

    SAVE_GCODE_STATE NAME=M600_state

    PAUSE

    G91

    G1 E-.8 F2700

    G1 Z{Z}

    G90

    G1 X{X} Y{Y} F3000

    G91

    G1 E-50 F1000

    RESTORE_GCODE_STATE NAME=M600_state

######################################################################

# BMP280/BME280/BME680 Environmental Sensor

######################################################################

# The macro below assumes you have a BME280 sensor_type defined in one

# of the applicable sections in printer.cfg, such as:

#

#[temperature_sensor my_sensor]

#sensor_type: BME280

#gcode_id: AMB

#

# Note the format of the parameter SENSOR in the macro below.  The BME280

# sensor status can be accessed using the format "bme280 <section_name>".

# The example section above is named "my_sensor", thus the bme280 can be

# queried as follows:

#

# QUERY_BME280 SENSOR='bme280 my_sensor'

#

# Since a default parameter is defined one could simply enter QUERY_BME280

# as well.

[gcode_macro QUERY_BME280]

gcode:

    {% set sensor = printer["bme280 my_sensor"] %}

    {action_respond_info(

        "Temperature: %.2f C\n"

        "Pressure: %.2f hPa\n"

        "Humidity: %.2f%%" % (

            sensor.temperature,

            sensor.pressure,

            sensor.humidity))}

######################################################################

# HTU21D family Environmental Sensor

######################################################################

# The macro below assumes you have a HTU21D sensor_type defined in one

# of the applicable sections in printer.cfg, such as:

#

#[temperature_sensor my_sensor]

#sensor_type: HTU21D

#

# Note the format of the parameter SENSOR in the macro below.  The HTU21D

# sensor status can be accessed using the format "htu21d <section_name>".

# The example section above is named "my_sensor", thus the htu21d can be

# queried as follows:

#

# QUERY_HTU21D SENSOR='htu21d my_sensor'

#

# Since a default parameter is defined one could simply enter QUERY_HTU21D

# as well.

[gcode_macro QUERY_HTU21D]

gcode:

    {% set sensor = printer["htu21d my_sensor"] %}

    {action_respond_info(

        "Temperature: %.2f C\n"

        "Humidity: %.2f%%" % (

            sensor.temperature,

            sensor.humidity))}

# SDCard 'looping' (aka Marlin M808 commands) support

#

# Support SDCard looping

[sdcard_loop]

# 'Marlin' style M808 compatibility macro for SDCard looping

[gcode_macro M808]

gcode:

    {% if params.K is not defined and params.L is defined %}SDCARD_LOOP_BEGIN COUNT={params.L|int}{% endif %}

    {% if params.K is not defined and params.L is not defined %}SDCARD_LOOP_END{% endif %}

    {% if params.K is defined and params.L is not defined %}SDCARD_LOOP_DESIST{% endif %}

    

[gcode_macro m205]

gcode:

  G4

[gcode_macro PAUSE]

description: Pause the actual running print

rename_existing: PAUSE_BASE

# change this if you need more or less extrusion

variable_extrude: 1.0

gcode:

  ##### read E from pause macro #####

  {% set E = printer["gcode_macro PAUSE"].extrude|float %}

  ##### set park positon for x and y #####

  # default is your max posion from your printer.cfg

  {% set x_park = printer.toolhead.axis_maximum.x|float - 5.0 %}

  {% set y_park = printer.toolhead.axis_maximum.y|float - 5.0 %}

  ##### calculate save lift position #####

  {% set max_z = printer.toolhead.axis_maximum.z|float %}

  {% set act_z = printer.toolhead.position.z|float %}

  {% if act_z < (max_z - 2.0) %}

      {% set z_safe = 2.0 %}

  {% else %}

      {% set z_safe = max_z - act_z %}

  {% endif %}

  ##### end of definitions #####

  PAUSE_BASE

  G91

  {% if printer.extruder.can_extrude|lower == 'true' %}

    G1 E-{E} F2100

  {% else %}

    {action_respond_info("Extruder not hot enough")}

  {% endif %}

  {% if "xyz" in printer.toolhead.homed_axes %}

    G1 Z{z_safe} F900

    G90

    G1 X{x_park} Y{y_park} F6000

  {% else %}

    {action_respond_info("Printer not homed")}

  {% endif %} 

[gcode_macro RESUME]

description: Resume the actual running print

rename_existing: RESUME_BASE

gcode:

  ##### read E from pause macro #####

  {% set E = printer["gcode_macro PAUSE"].extrude|float %}

  #### get VELOCITY parameter if specified ####

  {% if 'VELOCITY' in params|upper %}

    {% set get_params = ('VELOCITY=' + params.VELOCITY)  %}

  {%else %}

    {% set get_params = "" %}

  {% endif %}

  ##### end of definitions #####

  {% if printer.extruder.can_extrude|lower == 'true' %}

    G91

    G1 E{E} F2100

  {% else %}

    {action_respond_info("Extruder not hot enough")}

  {% endif %}  

  RESUME_BASE {get_params}

[gcode_macro CANCEL_PRINT]

description: Cancel the actual running print

rename_existing: CANCEL_PRINT_BASE

gcode:

  TURN_OFF_HEATERS

  CANCEL_PRINT_BASE

  

[display_status]

######################################################################

# Start Print and End Print

######################################################################

# Replace the slicer's custom start and end g-code scripts with

# START_PRINT and END_PRINT.

[gcode_macro START_PREHEAT]

gcode:

    {% set BED_TEMP = params.BED_TEMP|default(60)|float %}

    {% set EXTRUDER_TEMP = params.EXTRUDER_TEMP|default(200)|float %}

    # Start bed heating

    M140 S{BED_TEMP}

    M109 S{EXTRUDER_TEMP}

[gcode_macro END_PREHEAT]

gcode:

    # Turn off bed, extruder, and fan

  TURN_OFF_HEATERS