Lead screw delta and proper arm length



  • Hello,

    A week ago swapped the board on my delta printer from Lerdge to Duet, and I still cannot correctly set it up. So, the problem is following - if I put all the parameters that I have used on Lerdge to Duet config (with Delta_radius = printer_radius - slider_offset - effector_offset).

    Delta 6-factor autocalibration correct radius more or less okay, a deviation is ~0.005. But there is a problem with X and Y sizes, so I decided to adjust the arm's length, and the only way to get proper X and Y, I have to set arm length to 212.3125 while the physical length is 220, so it seems strange for me.

    So, do I have to set the arm's length to the real size and use M579 or keep it smaller than physical?

    PS: 7- or 9-factor autocalibration set unrealistic parameters, so I don't use them. Step\mm is definitely correct because I have a lead screw instead of belts.

    bed.g

    ; bed.g
    ; called to perform automatic delta calibration via G32
    ;
    ; generated by RepRapFirmware Configuration Tool v2 on Sat Feb 02 2019 19:10:31 GMT+0200 (Eastern European Standard Time)
    M561 ; clear any bed transform
    ; Probe the bed at 3 peripheral and 0 halfway points, and perform 3-factor auto compensation
    ; Before running this, you should have set up your Z-probe trigger height to suit your build, in the G31 command in config.g.
    G30 P0 X36.542 Y16.269 Z-99999
    G30 P1 X26.765 Y29.726 Z-99999
    G30 P2 X12.361 Y38.042 Z-99999
    G30 P3 X-4.181 Y39.781 Z-99999
    G30 P4 X-20 Y34.641 Z-99999
    G30 P5 X-32.361 Y23.511 Z-99999
    G30 P6 X-39.126 Y8.316 Z-99999
    G30 P7 X-39.126 Y-8.316 Z-99999
    G30 P8 X-32.361 Y-23.511 Z-99999
    G30 P9 X-20 Y-34.641 Z-99999
    G30 P10 X-4.181 Y-39.781 Z-99999
    G30 P11 X12.361 Y-38.042 Z-99999
    G30 P12 X26.765 Y-29.726 Z-99999
    G30 P13 X36.542 Y-16.269 Z-99999
    G30 P14 X40 Y0 Z-99999
    G30 P9 X0 Y0 Z-99999 S6
    

    config.g

    ; Configuration file for Duet WiFi (firmware version 1.21)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v2 on Sat Feb 02 2019 19:10:31 GMT+0200 (Eastern European Standard Time)
    
    ; General preferences
    G90                                         ; Send absolute coordinates...
    M83                                         ; ...but relative extruder moves
    M665 R110.855 L212.3125 B100 H171.671                     ; Set delta radius, diagonal rod length, printable radius and homed height
    M666 X1.53 Y-2.19 Z0.66             ; Put your endstop adjustments here, or let auto calibration find them
    
    ; Network
    M550 P"ScrewOne"                            ; Set machine name
    M552 S1                                     ; Enable network
    M586 P0 S1                                  ; Enable HTTP
    M586 P1 S0                                  ; Disable FTP
    M586 P2 S0                                  ; Disable Telnet
    
    ; Drives
    M569 P0 S1                                  ; Drive 0 goes forwards
    M569 P1 S1                                  ; Drive 1 goes forwards
    M569 P2 S1                                  ; Drive 2 goes forwards
    M569 P3 S0                                  ; Drive 3 goes backwards
    M350 X16 Y16 Z16 E16 I1                     ; Configure microstepping with interpolation
    M92 X400.00 Y400.00 Z400.00 E905.00         ; Set steps per mm
    M566 X1200.00 Y1200.00 Z1200.00 E1200.00    ; Set maximum instantaneous speed changes (mm/min)
    M203 X3000.00 Y3000.00 Z3000.00 E1200.00    ; Set maximum speeds (mm/min)
    M201 X50.00 Y50.00 Z50.00 E50.00            ; Set accelerations (mm/s^2)
    M906 X1000.00 Y1000.00 Z1000.00 E800.00 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30                                     ; Set idle timeout
    
    ; Axis Limits
    M208 Z0 S1                                  ; Set minimum Z
    
    ; Endstops
    M574 X2 Y2 Z2 S1                               ; Set active high endstops
    
    ; Z-Probe
    M558 P5 H5 I1 F120 T6000                       ; Set Z probe type to unmodulated and the dive height + speeds
    G31 P500 X0 Y37.7 Z2.94              ; Set Z probe trigger value, offset and trigger height
    M557 R30 S9                                 ; Define mesh grid
    
    ; Heaters
    M305 P0 T100000 B4138 R4700                 ; Set thermistor + ADC parameters for heater 0
    M143 H0 S120                                ; Set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4138 R4700                 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S280                                ; Set temperature limit for heater 1 to 280C
    
    ; Fans
    M106 P0 S0.3 I0 F500 H-1                    ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45                   ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Tools
    M563 P0 D0 H1 F2                               ; Define tool 0
    G10 P0 X0 Y0 Z0                             ; Set tool 0 axis offsets
    G10 P0 R0 S0                                ; Set initial tool 0 active and standby temperatures to 0C
    
    ; Automatic saving after power loss is not enabled
    
    ; Custom settings are not configured
    M557 R25 S10 ; probe within a radius of 25mm from the centre with a mesh spacing of 20mm
    M579 X1 Y1 ; 1.02
    M501
    

    config-override.g

    ; config-override.g file generated in response to M500 at 2019-02-04 20:48
    ; This is a system-generated file - do not edit
    ; Delta parameters
    M665 L212.3125 R110.709 H180.311 B100.0 X-0.876 Y-1.661 Z0.000
    M666 X0.700 Y-2.414 Z1.715 A0.00 B0.00
    ; Heater model parameters
    M307 H0 A90.0 C700.0 D10.0 S1.00 V0.0 B1
    M307 H1 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H2 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H3 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H4 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H5 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H6 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H7 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    G10 L2 P1 X0.00 Y0.00 Z0.00
    G10 L2 P2 X0.00 Y0.00 Z0.00
    G10 L2 P3 X0.00 Y0.00 Z0.00
    G10 L2 P4 X0.00 Y0.00 Z0.00
    G10 L2 P5 X0.00 Y0.00 Z0.00
    G10 L2 P6 X0.00 Y0.00 Z0.00
    G10 L2 P7 X0.00 Y0.00 Z0.00
    G10 L2 P8 X0.00 Y0.00 Z0.00
    G10 L2 P9 X0.00 Y0.00 Z0.00
    

  • administrators

    The rod length to use is the one that gives you best linearity. Print a grid pattern and pick the rod length that makes all the lines straight and evenly spaced. Then adjust scaling with M579.



  • @dc42

    thanks, I will try to do it. About rod length - is this okay if config will have the length that is different from the physical one if it provides good prints? May it affect somehow later?


  • administrators

    Sure, if using the wrong rod length gives you a flat bed height map and good linearity, go with it. It's probably helping to compensate for a geometrical error elsewhere in your printer.


 

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