Extruder skipping



  • I've recently rebuilt my printer to a clone of dc42:s precision kossel, but haven't switched heatbed yet and still running at 12v (planning to upgrade in the future). I'm using my old (small) 12v heatbed atm to try and get the printer working until I'm able to upgrade all the parts, but I'm having a problem that my extruder is skipping steps after 10-20 layers every print. Im trying to print a temperature tower in PLA (210 down to 170 degrees) but the print fails before lowering the temperature once. (https://www.thingiverse.com/thing:2493504)

    I'm using one of e3d:s titan extruders with a ~500mm bowden tube, with a smart effector. Pressure advance is not enabled. I've done multiple cold pulls, and there isn't any junk in the nozzle nor on the fillament, and I can see through it afterwards.
    Any ideas of what I have missed?

    Relative settings:

    M350 X128 Y128 Z128 E128 I0                 ; Configure microstepping without interpolation
    M92 X800.00 Y800.00 Z800.00 E6413.18        ; Set steps per mm
    M566 X1200.00 Y1200.00 Z1200.00 E600.00     ; Set maximum instantaneous speed changes (mm/min)
    M203 X18000.00 Y18000.00 Z18000.00 E3600.00 ; Set maximum speeds (mm/min)
    M201 X1000.00 Y1000.00 Z1000.00 E1000.00    ; Set accelerations (mm/s^2)
    M906 X1300.00 Y1300.00 Z1300.00 E1300.00 I30; Set motor currents (mA) and motor idle factor in per cent
    

  • administrators

    That sounds like insufficient hot end heatsink cooling. Check that the hot end heatsink fan is running smoothly when the hot end temperature exceeds 45C, that it is a 12V fan (not 24V), and that you have fitted it the right way round (label on the inside).



  • The fan is a 12V 30mm fan, fitted to blow air into the heatsink(label on the inside and arrow toward the hotend).

    Edit: the hotend fan is wired to an allways on pin, so its allways running at maximum speed.


  • administrators

    If you are using a thermistor to sense the hot end temperature, check your M305 P1 parameters. For the E3D thermistor it should be:

    M305 P1 B4725 C7.06e-8

    The online configurator incorrectly generates B4388 at present.



  • Ah, that might have been the culprit. I'm going to try the new values now.



  • @snimax said in Extruder skipping:

    M350 X128 Y128 Z128 E128 I0 ; Configure microstepping without interpolation

    I wouldn't be surprised if you're missing steps on retractions with those high microstepping values.

    Can you run an M122 after experiencing the skipping and post the result here?

    I'd suggest reverting to x16 microsteps with interpolation and trying again.



  • With the new values, the print makes it further but, I've still to finish a single print.

    @phaedrux said in Extruder skipping:

    I wouldn't be surprised if you're missing steps on retractions with those high microstepping values.

    Can you run an M122 after experiencing the skipping and post the result here?

    I'd suggest reverting to x16 microsteps with interpolation and trying again.

    I haven't investigated retraction skipping, retraction is disabled for now. I'm having problems with just normal print extrusion, but im going to try lowering to 16x microstepping and using interpolation instead.

    Here is a printout of M122:

    === Diagnostics ===
    RepRapFirmware for Duet 2 WiFi/Ethernet version 2.02(RTOS) running on Duet WiFi 1.02 or later
    Board ID: 08DAM-9K9K2-NGNSN-6J9D6-3SJ6S-T5U3M
    Used output buffers: 3 of 20 (20 max)
    === RTOS ===
    Static ram: 25524
    Dynamic ram: 98660 of which 0 recycled
    Exception stack ram used: 424
    Never used ram: 6464
    Tasks: NETWORK(ready,544) HEAT(blocked,1232) MAIN(running,656) IDLE(ready,200)
    Owned mutexes:
    === Platform ===
    Last reset 00:44:42 ago, cause: power up
    Last software reset time unknown, reason: User, spinning module GCodes, available RAM 6660 bytes (slot 0)
    Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0440f000 BFAR 0xe000ed38 SP 0xffffffff Task 0x4e49414d
    Error status: 12
    Free file entries: 9
    SD card 0 detected, interface speed: 20.0MBytes/sec
    SD card longest block write time: 0.0ms, max retries 0
    MCU temperature: min 35.9, current 36.2, max 36.5
    Supply voltage: min 11.0, current 11.8, max 11.9, under voltage events: 0, over voltage events: 0, power good: yes
    Driver 0: ok, SG min/max 0/254
    Driver 1: ok, SG min/max 0/252
    Driver 2: ok, SG min/max 0/176
    Driver 3: ok, SG min/max not available
    Driver 4: standstill, SG min/max not available
    Date/time: 2019-02-16 20:06:21
    Cache data hit count 4294967295
    Slowest loop: 3.18ms; fastest: 0.08ms
    I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0
    === Move ===
    Hiccups: 14, StepErrors: 0, LaErrors: 0, FreeDm: 135, MinFreeDm: 122, MaxWait: 0ms, Underruns: 0, 0
    Scheduled moves: 6877, completed moves: 6847
    Bed compensation in use: mesh
    Bed probe heights: -0.047 -0.091 -0.086 -0.089 -0.064
    === Heat ===
    Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1
    Heater 0 is on, I-accum = 0.5
    Heater 1 is on, I-accum = 0.4
    === GCodes ===
    Segments left: 1
    Stack records: 2 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 doing "G0 F7200 X19.209 Y-0.024" 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 ===
    Slowest loop: 201.05ms; fastest: 0.08ms
    Responder states: HTTP(0) 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 6
    WiFi firmware version 1.22
    WiFi MAC address 5c:cf:7f:f8:2b:e7
    WiFi Vcc 3.37, reset reason Turned on by main processor
    WiFi flash size 4194304, free heap 28096
    WiFi IP address 192.168.0.3
    WiFi signal strength -51dBm, reconnections 0, sleep mode modem
    Socket states: 0 0 0 0 0 0 0 0
    

  • administrators

    @phaedrux said in Extruder skipping:

    @snimax said in Extruder skipping:

    M350 X128 Y128 Z128 E128 I0 ; Configure microstepping without interpolation

    I wouldn't be surprised if you're missing steps on retractions with those high microstepping values.

    Can you run an M122 after experiencing the skipping and post the result here?

    I'd suggest reverting to x16 microsteps with interpolation and trying again.

    I agree, the E steps/mm is extremely high.



  • @dc42 What is a reasonable steps/mm value?


  • administrators

    @snimax said in Extruder skipping:

    @dc42 What is a reasonable steps/mm value?

    I suggest between 400 and 1000.



  • @dc42 should I use any interpolation or only microstepping?
    My towers are using 1.8 degree stepper motors and the titan is running a 0.9 degree stepper. If I understand the documentation correctly its only possible to set the same interpolation for all the drives, causing the steps/mm for the extruder way above the range.



  • You can set interpolation for x16 microstepping only. You can do it on a per drive basis if you wish, but there is likely no need.

    If you set your steps per mm for x16 microstepping the interpolation doesn't enter into it at all. The driver will just take the 16 microsteps and insert additional steps for the motors causing them to run smoother and quieter.



  • @phaedrux So if I set the microstepping to 16 on each drive with interpolation I should still use 16 in the calculation for steps?
    steps/mm = (200 * (16 or 128))/(2 * 16)



  • Yes it's always best to use x16 for calculation of the steps per mm, because if you set the steps per mm based on x16 the firmware can do the calculations for you automatically if you decide to change the microstepping later.

    For example

    ; 16i steps extruder config
    M350 X16 Y16 Z16 E16 I1	; Configure microstepping with interpolation
    M92 X200 Y200 Z6400 E805   ; Set steps per mm for x16 microsteps
    
    ;higher extruder microstepping
    M350 E64 I0	; Configure higher microstepping without interpolation for extruder.
    

    The second M350 for the extruder will automatically recalculate the steps per mm value without me having to do anything.



  • @phaedrux Ah okey, thanks for the example. I'm going to recalibrate the extruder for 16 microstepps and try again.



  • So I followed your recommendation to run with 16 microstepping and interpolation and made it halfway through the temperature tower before the extruder started skipping again at 195 degrees. There was still no debris in the nozzle and i can push material through the nozzle with ease.

    The new steps/mm settings:
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X100.00 Y100.00 Z100.00 E:795 ; Set steps per mm

    Heater settings:
    M305 T100000 B4725 C7.06e-8 R4700

    I did run a temperature tuning after changing to the correct B and C values which produced:
    M307 H1 A629.4 C282.2 D4.4 S1.00 V11.7 B0

    Here is a M122 printout from when the extruder started skipping this time:

    === Diagnostics ===
    RepRapFirmware for Duet 2 WiFi/Ethernet version 2.02(RTOS) running on Duet WiFi 1.02 or later
    Board ID: 08DAM-9K9K2-NGNSN-6J9D6-3SJ6S-T5U3M
    Used output buffers: 3 of 20 (20 max)
    === RTOS ===
    Static ram: 25524
    Dynamic ram: 98660 of which 0 recycled
    Exception stack ram used: 432
    Never used ram: 6456
    Tasks: NETWORK(ready,544) HEAT(blocked,1232) MAIN(running,632) IDLE(ready,200)
    Owned mutexes:
    === Platform ===
    Last reset 02:13:26 ago, cause: software
    Last software reset time unknown, reason: User, spinning module GCodes, available RAM 6616 bytes (slot 2)
    Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0440f000 BFAR 0xe000ed38 SP 0xffffffff Task 0x4e49414d
    Error status: 12
    Free file entries: 9
    SD card 0 detected, interface speed: 20.0MBytes/sec
    SD card longest block write time: 5.0ms, max retries 0
    MCU temperature: min 35.0, current 35.9, max 36.7
    Supply voltage: min 11.0, current 11.8, max 12.0, under voltage events: 0, over voltage events: 0, power good: yes
    Driver 0: ok, SG min/max 0/293
    Driver 1: ok, SG min/max 0/302
    Driver 2: ok, SG min/max 0/276
    Driver 3: ok, SG min/max 0/1023
    Driver 4: standstill, SG min/max not available
    Date/time: 2019-02-16 23:43:33
    Cache data hit count 4294967295
    Slowest loop: 17.83ms; fastest: 0.08ms
    I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0
    === Move ===
    Hiccups: 0, StepErrors: 0, LaErrors: 0, FreeDm: 141, MinFreeDm: 120, MaxWait: 180350ms, Underruns: 0, 0
    Scheduled moves: 86403, completed moves: 86375
    Bed compensation in use: mesh
    Bed probe heights: 0.029 -0.016 -0.049 -0.052 -0.012
    === Heat ===
    Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1
    Heater 0 is on, I-accum = 0.6
    Heater 1 is on, I-accum = 0.4
    === GCodes ===
    Segments left: 1
    Stack records: 2 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 doing "G1 F1200 X10.819 Y-1.059 E0.00483" 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 ===
    Slowest loop: 200.65ms; fastest: 0.08ms
    Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0) Telnet(0)
    HTTP sessions: 2 of 8
    - WiFi -
    Network state is running
    WiFi module is connected to access point 
    Failed messages: pending 0, notready 0, noresp 1
    WiFi firmware version 1.22
    WiFi MAC address 5c:cf:7f:f8:2b:e7
    WiFi Vcc 3.37, reset reason Turned on by main processor
    WiFi flash size 4194304, free heap 27000
    WiFi IP address 192.168.0.3
    WiFi signal strength -52dBm, reconnections 0, sleep mode modem
    Socket states: 0 0 0 0 0 0 0 0
    


  • @snimax said in Extruder skipping:

    Supply voltage: min 11.0, current 11.8, max 12.0

    Does your power supply have an adjustment knob to dial it up slightly?

    What extruder motor are you using? Your motor currents should be around 70-85% of the rated max. Too low a motor current could cause skipping.

    How fast are you trying to print? Dropping the temperature and printing fast (high volumetric flow rate) can cause insufficient melting and increased back pressure, causing skipping.

    Are you confident that the temperatures being reported are accurate? What thermistor are you using and are you confident you have the right values for it? It's possible that the real temperature is much lower than reported.



  • Does your power supply have an adjustment knob to dial it up slightly?

    No, Im using a ATX power supply (Corsair VS550) which should be able to provide the required power.

    What extruder motor are you using? Your motor currents should be around 70-85% of the rated max. Too low a motor current could cause skipping.

    Im using this e3d motor rated at 1.68A and I'm currently using 1.3A to supply it.

    How fast are you trying to print? Dropping the temperature and printing fast (high volumetric flow rate) can cause insufficient melting and increased back pressure, causing skipping.

    I'm trying to print in 40 mm/s with the first layers at 20mm/s

    Are you confident that the temperatures being reported are accurate? What thermistor are you using and are you confident you have the right values for it? It's possible that the real temperature is much lower than reported.

    I'm using a standard e3d thermistor. The configuration I got from the web configurator was wrong which was pointed out by dc42, so for the last 5 tests I've been using M305 P1 B4725 C7.06e-8.


  • administrators

    @snimax said in Extruder skipping:

    So I followed your recommendation to run with 16 microstepping and interpolation and made it halfway through the temperature tower before the extruder started skipping again at 195 degrees. There was still no debris in the nozzle and i can push material through the nozzle with ease.

    That suggests insufficient torque from the extruder motor, or just possibly a partially-blown extruder stepper driver. Which motor are you using?



  • Post a gcode of the print so we can try reproducing the problem. The model alone is not enough and the thingiverse link takes an hour to load for me at the moment.

    We also don't see your entire config.g.


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