Delta calibration first step

  • Hi all,

    I replaced a old Rumba board in a Tripodmaker bpack editing to a Duet 2 WiFi. Everything worked out so far, but I am stuck on calibrating the machine.

    I measured the delta's geometry as accurately as possible:
    L: 335mm
    R: 185mm

    I checked these measurements several times and they are correct. For some reason, the vector plate moves very clearly in an arc (difference of about 5-10mm between center and periphery). Did I configure the delta parameters wrong?

    What can I do to get the vector plate to move horizontal?

    Thanks in advance.


    ; Configuration file for Duet WiFi (firmware version 3)
    ; executed by the firmware on start-up
    ; generated by RepRapFirmware Configuration Tool v3.1.3 on Tue Jun 30 2020 00:49:16 GMT+0200 (Midden-Europese zomertijd)

    ; General preferences
    G90 ; send absolute coordinates...
    M83 ; ...but relative extruder moves
    M550 P"3DPrintert" ; set printer name
    M665 R185 L355 B115 H350 ; Set delta radius, diagonal rod length, printable radius and homed height
    M666 X0 Y0 Z0 ; put your endstop adjustments here, or let auto calibration find them

    ; Network
    M552 S1 ; enable network
    ;M552 S2 ; enable access point mode
    M586 P0 S1 ; enable HTTP
    M586 P1 S1 ; enable FTP
    M586 P2 S0 ; disable Telnet

    ; Drives
    M569 P0 S0 ; physical drive 0 goes forwards
    M569 P1 S0 ; physical drive 1 goes forwards
    M569 P2 S0 ; physical drive 2 goes forwards
    M569 P3 S0 ; physical drive 3 goes forwards
    M584 X0 Y1 Z2 E3 ; set drive mapping
    M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation
    M92 X133.33 Y133.33 Z133.33 E400.49 ; set steps per mm
    M566 X1200.00 Y1200.00 Z1200.00 E1200.00 ; set maximum instantaneous speed changes (mm/min)
    M203 X18000.00 Y18000.00 Z18000.00 E1200.00 ; set maximum speeds (mm/min)
    M201 X1000.00 Y1000.00 Z1000.00 E1000.00 ; set accelerations (mm/s^2)
    M906 X1400 Y1400 Z1400 E1400 I10 ; 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 S1 P"xstop" ; configure active-high endstop for high end on X via pin xstop
    M574 Y2 S1 P"ystop" ; configure active-high endstop for high end on Y via pin ystop
    M574 Z2 S1 P"zstop" ; configure active-high endstop for high end on Z via pin zstop

    ; Z-Probe
    M558 P5 C"!" H5 F120 T6000 ; set Z probe type to unmodulated and the dive height + speeds
    G31 P500 X-7 Y-24 Z2.05 ; set Z probe trigger value, offset and trigger height
    M557 R85 S20 ; define mesh grid

    ; Heaters
    M308 S0 P"bedtemp" Y"thermistor" T100000 B3950 ; configure sensor 0 as thermistor on pin bedtemp
    M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0
    M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit
    M140 H0 ; map heated bed to heater 0
    M143 H0 S120 ; set temperature limit for heater 0 to 120C
    M308 S1 P"e0temp" Y"thermistor" T100000 B4725 C7.06e-8 ; configure sensor 1 as thermistor on pin e0temp
    M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
    M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit

    ; Fans
    M950 F0 C"fan0" Q500 ; create fan 0 on pin fan0 and set its frequency
    M106 P0 C"BOTTOM" S0 H-1 ; set fan 0 name and value. Thermostatic control is turned off
    M950 F1 C"fan1" Q500 ; create fan 1 on pin fan1 and set its frequency
    M106 P1 C"EXTRUDER" S1 H1 T45 ; set fan 1 name and value. Thermostatic control is turned on
    M950 F2 C"fan2" Q500 ; create fan 2 on pin fan2 and set its frequency
    M106 P2 C"BED" S1 H-1 ; set fan 2 name and value. Thermostatic control is turned off

    ; Tools
    M563 S"Printhead 1" P0 D0 H1 F1; tool 0 uses extruder drive 0 and heater 1
    G10 P0 S0 R0 X0 Y0 ; set tool 0 temperatures and offsets

  • Moderator

    I'm not a delta expert, but I can point you at these docs in case you haven't seen them yet.

  • Thank you for your reply. I've read both of the documentation pages entirely and thoroughly.

    I'm just not managing to get my calibration on the right track. My main issue is that before any calibration my vector plate already moves in a clear arc, so something is off. Next to that my printer has an adjustable bed with three screws, which I somehow need to get flat. Because my vector plate is not moving horizontally this is not possible to do manually by adjusting the screws. Auto calibration seems to do something very weird when I use 8 factor to calculate bed tilt.

    I'm using a NPN inductive probe that's fairly far from the nozzle, so before doing any auto calibration I wanted to test it's repeatability. I don't get however how I could manage that with a vector plate that's not moving straight and a tilted bed 😅.

    Where should I start?

  • administrators

    1. Check that you have entered the rod lengths (measured between bearing centres) correcty in the M665 command.
    2. Start with 4-factor auto calibration to get the effector moving approximately horizontally. You will need to set the dive height (M558 H parameter) high temporarily to avoid collisions with the bed, until you have an approximate calibration.
    3. Then measure the probe trigger height (measured nozzle height above the bed at the point where the probe triggers) at various places across the bed. You will need a set of feeler gauges. If it is not consistent (which is quite likely with an offset probe), then auto calibration is not going to work well for you until you sort that out.

  • Thank you for the response!

    I measured the diagonal rod length and horizontal distance a few times already and they seem to be right. What could be the cause of my vector plate moving in an arc?

    How could I set my build plate as horizontal as possible before doing an auto calibration? If the build plate is tilted before doing an auto calibration the delta geometry parameters will be adjusted to this tilt right? Isn't that bad?

    Should I perform the 4-factor auto calibration with my sensor or use manual mode? To be able to use the sensor I would have to know the trigger height already right?

    Just to be sure that I get the procedure you are proposing:

    • auto calibrate with 4 factors to get the delta geometry to get closer to its true values.
    • once vector plate is moving horizontally I can start testing the repeatability of my probe.
    • If probe is not okay I'll have to replace it or use manual calibration.

    Thanks for the help!

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