Extruder skipping

Snimax

@dc42 What is a reasonable steps/mm value?

dc42

@dc42 What is a reasonable steps/mm value?

I suggest between 400 and 1000.

Snimax

@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.

Phaedrux

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.

Snimax

@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)

Phaedrux

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.

Snimax

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

Snimax

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

Phaedrux

@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.

Snimax

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.

dc42

@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?

Edgars Batna

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.

Snimax

@dc42 said in Extruder skipping:

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

Im using a MT-1703HSM168RE which should provide 2.5kg/cm in holding torque. I could try switching to E1 instead to see if the E0 driver is the problem.

@Edgars-Batna
Good point. Here is the gcode file I'm using: gcode file.

Here is the full config file as im trying the same print with E1 instead of E0:

; Configuration file for Duet WiFi (firmware version 1.21)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v2 on Thu Jan 31 2019 14:18:29 GMT+0100 (Central European Standard Time)

; General preferences
G90                                         ; Send absolute coordinates...
M83                                         ; ...but relative extruder moves
M665 L360.220 R214.972 H727.362 B110.0 X-0.121 Y-0.016 Z0.000   ; Set delta radius, diagonal rod length, printable radius and homed height
M666 X-6.661 Y-0.627 Z7.288 A0.00 B0.00                         ; Put your endstop adjustments here, or let auto calibration find them

; Network
M552 S1                                     ; Enable network
M586 P0 S1                                  ; Enable HTTP
M586 P1 S0                                  ; Disable FTP
M586 P2 S0                                  ; Disable Telnet

; Drives
M584 X0 Y1 Z2 E4                            ; Set extruder to use E1 instead of E0
M569 P0 S1                                  ; Drive 0 goes forwards
M569 P1 S1                                  ; Drive 1 goes forwards
M569 P2 S1                                  ; Drive 2 goes forwards
M569 P3 S1                                  ; Drive 3 goes forwards
M569 P4 S1                                  ; Drive 3 goes forwards
M350 X16 Y16 Z16 E16 I1                     ; Configure microstepping with interpolation
M92 X100.00 Y100.00 Z100.00 E:795          ; 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
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 P8 R0.6 H5 F1200 T6000 A1 B1           ; Set Z probe type to effector and the dive height + speeds, and turns off bed heater since the psu doenst have enough power
G31 P80 X0 Y0 Z-0.1                         ; Set Z probe trigger value, offset and trigger height
M557 R100 S10                               ; Define mesh grid

; Heaters
M307 H0 B0 S1.00                            ; Disable bang-bang mode for the bed heater and set PWM limit
M305 P0 S"Heat bed" T101200 B4267 R4700                 ; Set thermistor + ADC parameters for heater 0
M143 H0 S120                                ; Set temperature limit for heater 0 to 120C
M305 P1 S"Extruder 1" T100000 B4725 C7.06e-8 R4700        ; Set thermistor + ADC parameters for heater 1
M143 H1 S280                                ; Set temperature limit for heater 1 to 280C

; Fans
M106 P0 S0   I0 F500 H-1                    ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
M106 P1 S1 I0 F500 H T45                    ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
M106 P2 S1 I0 F500 H T45                    ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on

; Tools
M563 P0 D0 H1                               ; 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

M912 P0 S-5.8                               ; Calibrate CPU temperature
;M572 D0 S0.3                                ; Enable pressure advance
M501                                        ; Load config-override

Snimax

The problem still persists when I changed the stepper driver. I have not used the E1 driver before so I think it is unlikely that the stepper driver is faulty.

I'm going to try and print it without the heated (if I can manage to get good adhesion) to see if the problem is too low power.

dc42

Is the motor definitely skipping steps, not the hobbed shaft losing its grip on the filament?

Snimax

The power seems to be the last hurdle together with the other fixes since I've managed to print the whole tower without extruder stepper problems. The last sections are under extruded but it was expected from the filament properties.

I guess it means that it is time to bite the bullet and upgrade the last parts of the printer as well, but thank you all for your input and help.