Jerky movement in X axis when carving



  • I just did my first real carving since setting up my custom CNC and it seems to move very jerky in the X axis direction while carving. When i move it from location to location its great, super smooth no issue but when its doing a 3d carving moving slow in the X direction it seems to struggle then jump.


  • Moderator

    More technical details please.



  • @chichirod by 3d carving do you mean all 3 axis moving at the same time? If so post the g code program for those moves



  • @3DPMicro The machine is only moving the X axis and Z axis when the jerkiness seems to happen. When its running at a consistant level its very smooth but as it lifts to carve a piece it jumps instead of being a smooth transition. Here is the Gcode:Eagle rough 2 0.25em.gcode


  • Moderator

    Config please. Sounds like Z speed settings could be too low



  • @Phaedrux The machine is only moving the X axis and Z axis when the jerkiness seems to happen. When its running at a consistent (not lowering or raising the Z axis) level its very smooth and quick, but as it lifts to carve a piece it jumps instead of being a smooth transition.



  • @Phaedrux ; Configuration file for Duet 3 (firmware version 3)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v2.1.8 on Fri Mar 06 2020 14:56:26 GMT-0700 (Mountain Standard Time)

    ; General preferences
    G90 ; send absolute coordinates...
    M83 ; ...but relative extruder moves
    M550 P"Duet3 CNC" ; set printer name

    ; Network
    M552 P0.0.0.0 S1 ; enable network and acquire dynamic address via DHCP
    M586 P0 S1 ; enable HTTP
    M586 P1 S0 ; disable FTP
    M586 P2 S0 ; disable Telnet

    ; Drives
    M569 P0.0 S1 ; physical drive 0.0 goes forwards
    M569 P0.1 S0 ; physical drive 0.1 goes backwards
    M569 P0.2 S0 ; physical drive 0.2 goes backwards
    M569 P0.3 S0 ; physical drive 0.3 goes backwards
    M584 X0.0:0.3 Y0.1 Z0.2 ; set drive mapping
    M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation
    M92 X80.00 Y80.00 Z400.00 E80.00 ; set steps per mm
    M566 X900.00 Y900.00 Z12.00 E900.00 ; set maximum instantaneous speed changes (mm/min)
    M203 X12000.00 Y12000.00 Z1800.00 E12000.00 ; set maximum speeds (mm/min)
    M201 X500.00 Y500.00 Z20.00 E500.00 ; set accelerations (mm/s^2)
    M906 X2800 Y2800 Z4200 E2800 I30 ; set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout

    ; Axis Limits
    M208 X0 Y0 Z0 S1 ; set axis minima
    M208 X2498 Y1245 Z140 S0 ; set axis maxima

    ; Endstops
    M574 X1 S1 P"io0.in" ; configure active-high endstop for low end on X via pin io0.in
    M574 Y1 S1 P"io1.in" ; configure active-high endstop for low end on Y via pin io1.in
    M574 Z2 S1 P"io2.in" ; configure active-high endstop for high end on Z via pin io2.in

    ; Z-Probe
    M558 P0 H5 F120 T12000 ; disable Z probe but set dive height, probe speed and travel speed
    M557 X15:215 Y15:195 S20 ; define mesh grid

    ; Heaters
    M308 S0 P"temp0" Y"thermistor" T1 B4138 ; configure sensor 0 as thermistor on pin temp0
    M950 H0 C"out0" T0 ; create bed heater output on out0 and map it to sensor 0
    M143 H0 S0 ; set temperature limit for heater 0 to 0C
    M307 H0 B0 S0.00 ; disable bang-bang mode for the bed heater and set PWM limit
    M140 H0 ; map heated bed to heater 0

    ; Fans

    ; Tools

    ; Custom settings
    M307 H1 A-1 C-1 D-1 ; Disable Heater 1 so we can use it for a tool
    M453 P0 R24000 F400 ; Set to CNC mode, using Tool 0, 24000 Max RPM, PWM Frequency 400hz

    ; Miscellaneous
    M501 ; load saved parameters from non-volatile memory
    M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss


  • Moderator

    Yes increase your zspeeds acceleration and jerk. Do some testing to see if it's still in the limits and try again. Dry run first.



  • @Phaedrux Awesome, thank you. Any recommendations on how high to go to?


  • Moderator

    That's what the testing is for, but Start with 10x your current values. It's the 12mm/min jerk that is the biggest problem I think.



  • @Phaedrux Ok, I just wanted a starting point. Ill start playing. Thank you



  • @Phaedrux That was definitely it. It moves way better. A bit more tweaking and its all good


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