Question on Z-Offset and Start Script, Also Nozzle Adjustment.



  • Hello again!

    Hoping someone can help me.

    I just got the DuetWifi setup and everything is going pretty good except I can't figure out how to adjust the Z-Offset.

    I set the trigger height, but I believe my start script in Cura is ignoring/overwriting that.

    How do I set the Z-Offset and tell it to extrude a purge line at the front of bed without messing up the Z-Offset?

    Also, the nozzle is way off from where it should be. Is there a way to change this where it actually prints in the center of the bed instead of somewhere else even though the model is positioned in the center?

    Thanks!
    Justin


  • administrators

    @justinds89 said in Question on Z-Offset and Start Script, Also Nozzle Adjustment.:

    Hello again!

    Hoping someone can help me.

    I just got the DuetWifi setup and everything is going pretty good except I can't figure out how to adjust the Z-Offset.

    I set the trigger height, but I believe my start script in Cura is ignoring/overwriting that.

    If you are homing Z using the Z probe then setting the trigger height should be all you need to do. However, in some firmware versions the Z height can be off if you re-home Z when mesh bed compensation is applied. So either turn of mesh bed compensation when homing Z, or use recent firmware (2.01 is current).

    Also, the nozzle is way off from where it should be. Is there a way to change this where it actually prints in the center of the bed instead of somewhere else even though the model is positioned in the center?

    Use the M208 commands in config.g to define the position of the nozzle when the X and Y homing switches trigger. I make X0 Y0 the centre of the bed on all my printers, so on my Cartesian printer with 210x210mm bed I use:

    M208 X107 Y105 Z190 ; set axis maxima
    M208 X-113 Y-105 Z-1 S1 ; set axis minima

    meaning that the lowest reachable X position is 113mm left of bed centre (which is also where the X-min endstop triggers) and the highest reachable X position is 107mm right of bed centre; and similarly for Y. But you can make X0 Y0 the corner of the bed if you prefer.



  • @dc42

    Ah okay that cleared things up a bit and I think I actually have everything setup properly with a bit a of tweaking still needing done.

    I have one issue though that I don't really understand what is happening.

    When printing it is laying down the first few layers great, but after about 4 or 5 layers it stops laying down layers and just balling the filament up around the nozzle.

    Is this something in the firmware that could be wrong? I was wondering if the Z axis is moving too far and eventually gets too far away form the nozzle to properly lay the layer down.

    Thanks for the help!



  • @justinds89 Plastic balling up like that could be due to over extrusion. Have you calibrated your extruder to make sure the steps per mm are accurate?

    A photo of the problem could help diagnose the issue.



  • @phaedrux

    Yes I have calibrated it where it extrudes exactly 100mm of filament when that is what I select to extrude. Verified with measurements.

    I will run another print for awhile this evening and post back a picture as I really need to get this sorted and I'm a bit lost on where to go from here.

    I don't believe it is over extrusion though as it looks great up until that point.



  • What type of printer is it?
    Can you also post your config.g?
    Are you using anything like variable layer height in Cura?
    If you manually command the z axis to move 100mm does it actually move 100mm when measured?
    Are you using mesh grid compensation?



  • @phaedrux Thanks for the quick reply.

    This is a modified Flashforge Dreamer with E3D Titan being used.
    I will post my conf.g in about an hour as I do not have access to it right now.
    I do use variable layer height, but for testing I have just been using .1mm layer height.
    Not sure on the Z distance, that is one thing I was going to check. I have not yet though, but will here soon as I get a chance.
    I am using the Auto Compensation from Duet as I do not have a probe.

    Hopefully this helps.



  • @phaedrux My Z Axis was off .5mm during a 100mm test. I have since corrected this.

    It prints great for a few later and then it starts grinding through the filament and quits feeding. It didn't get balled up this time.

    0_1533159800943_MVIMG_20180801_163503.jpg

    0_1533159488250_config.g



  • @phaedrux

    It looks like it is messing up on the second layer every time now. First layer looks great!

    0_1533161438875_IMG_20180801_170830.jpg



  • What material are you printing? It looks like the second layer isn't bonding at all. I've seen that happen when trying to print ABS with too little heat and too much cooling fan.

    Does your nozzle have a blockage? Can you do an atomic pull on the hot end?



  • @phaedrux I'm printing with PLA. No blockage as I already checked and put in a new nozzle.

    It keeps grinding the filament after a layer or two.

    I'm not sure this is a problem with a setup of the board at this point.

    Not sure what could be causing it.



  • Can you extrude into free air without issue? Trying to eliminate the extruder as possible issue.



  • Can you run an M122 in the console and post resulting diagnostic?

    I notice in your config that you have 2 extruders specified. Are they the same? Some of the values differ.

    M350 X16 Y16 Z16 E16:16 I1                   ; Configure microstepping with interpolation
    M92 X100 Y100 Z400 E624:582                    ; Set steps per mm
    M566 X1200 Y1200 Z18 E300:300                ; Set maximum instantaneous speed changes (mm/min)
    M203 X6000 Y6000 Z180 E1200:1200             ; Set maximum speeds (mm/min)
    M201 X1000 Y1000 Z100 E5000:5000             ; Set accelerations (mm/s^2)
    M906 X1000 Y1000 Z1000 E1000:1600 I30        ; Set motor currents (mA) and motor idle factor in per cent
    


  • Do you have other filament to test with? Perhaps your PLA has gone stale.
    Or perhaps the hotend is not getting as hot as you expect it to? That could explain the poor adhesion.
    Can you verify the temperature of the hotend with a thermocouple?
    Are the temps stable?
    Have you run a PID tune on the hotends yet?
    Are you sure your thermistor values in config.g are correct?

    Sorry for the shotgun blast of ideas.



  • I only have one extruder so I'm not sure why it shows two or how exactly to fix that.

    As for extruding into free air. It appears to do this just fine (have extruded several hundred mms this way).



  • I can try with other filament yes even though before the build I was using this filament.

    I am using a PT1000 sensor and it shows the temp at room temperature is accurate. I'm not sure how to very if it is accurate when heated up though.

    The temps do remain stable.

    Here is the diagnostic.
    M122
    === Diagnostics ===
    Used output buffers: 4 of 32 (10 max)
    === Platform ===
    RepRapFirmware for Duet 2 WiFi/Ethernet version 1.21 running on Duet WiFi 1.02 or later
    Board ID: 08DGM-956GU-DJMSN-6J1FA-3SN6P-TUNZF
    Static ram used: 16152
    Dynamic ram used: 100448
    Recycled dynamic ram: 2184
    Stack ram used: 1224 current, 4512 maximum
    Never used ram: 7776
    Last reset 00:00:22 ago, cause: software
    Last software reset at 2018-08-01 18:15, reason: User, spinning module GCodes, available RAM 7776 bytes (slot 1)
    Software reset code 0x0003 HFSR 0x00000000, CFSR 0x00000000, ICSR 0x04417000, BFAR 0xe000ed38, SP 0xffffffff
    Error status: 0
    Free file entries: 10
    SD card 0 detected, interface speed: 20.0MBytes/sec
    SD card longest block write time: 0.0ms
    MCU temperature: min 27.0, current 27.5, max 28.4
    Supply voltage: min 24.3, current 24.4, max 24.6, under voltage events: 0, over voltage events: 0
    Driver 0: standstill, SG min/max not available
    Driver 1: standstill, SG min/max not available
    Driver 2: standstill, SG min/max not available
    Driver 3: standstill, SG min/max not available
    Driver 4: standstill, SG min/max not available
    Date/time: 2018-08-01 18:16:13
    Slowest main loop (seconds): 0.014056; fastest: 0.000046
    === Move ===
    MaxReps: 0, StepErrors: 0, LaErrors: 0, FreeDm: 240, MinFreeDm 240, MaxWait: 0ms, Underruns: 0, 0
    Scheduled moves: 0, completed moves: 0
    Bed compensation in use: none
    Bed probe heights: 0.000 0.000 0.000 0.000 0.000
    === Heat ===
    Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1
    Heater 1 is on, I-accum = 0.0
    === GCodes ===
    Segments left: 0
    Stack records: 1 allocated, 0 in use
    Movement lock held by null
    http is idle in state(s) 0
    telnet is idle in state(s) 0
    file is idle in state(s) 0
    serial is idle in state(s) 0
    aux is idle in state(s) 0
    daemon is idle in state(s) 0
    queue is idle in state(s) 0
    autopause is idle in state(s) 0
    Code queue is empty.
    === Network ===
    Responder states: HTTP(1) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0) Telnet(0)
    HTTP sessions: 1 of 8

    • WiFi -
      Network state is running
      WiFi module is connected to access point
      Failed messages: pending 0, notready 0, noresp 0
      WiFi firmware version 1.21RC4(08b3)
      WiFi MAC address 00:00:00:00:00:00
      WiFi Vcc 3.34, reset reason Turned on by main processor
      WiFi flash size 4194304, free heap 17088
      WiFi IP address 0.0.0.0
      WiFi signal strength -39dBm, reconnections 0, sleep mode modem
      Socket states: 2 0 0 0 0 0 0 0
      === Expansion ===


  • That is fine. I appreciate the help as I'm stuck on what to do.

    I am fairly certain I have the thermistor values correct in config.g.

    I have not PID tuned them and I'm not really familiar with the process.



  • According to this: https://duet3d.dozuki.com/Wiki/Connecting_thermistors_or_PT1000_temperature_sensors#Section_PT1000_sensors
    I don't think you have your PT1000 configured correctly.

    You currently have

    M305 P1 T100000 B4138 C0 R4700               ; Set thermistor + ADC parameters for heater 1
    

    but should have

    M305 P1 X501 R4700
    

    That could explain your actual temperature being different from what's reported.



  • Here is the wiki for tuning the heaters.

    https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control

    Getting the temps correct will be first step.



  • Okay, I will check this out and report back. Thanks!

    I can confirm it does the same thing with different filament.


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