Extruder sometimes cuts out in middle of long prints

brandonh

Thanks in advance - this issue is a bummer, where occasionally you lose a print many hours in, and don't have hard evidence for anything.

In long prints, I'm seeing occasional cases where my Duet WiFi (running 1.21 firmware) seems to stop driving the extruder motor, causing a print to fail, with no easy way to recover it. This has happened at least twice now, and I don't recall seeing this failure mode before the 1.21 release (but don't quote me). This issue has happened a few hours into each print but not at the same time. The file is known-good, and the printer has done multiple of these 5 hr prints (plantygons) successfully.

When it happens, the printer (a delta) keeps moving happily, but there's no extruder motion, and the last time I checked, the extruder motor even seemed fairly cool to the touch. The drivers are actively cooled and all were cool to the touch, so I don't think that's the issue. After pausing the print, the extruder had no issue. It extruded and retracted happily via the PanelDue right after. Plus, the pull I did after was fine.

One possibility is shown in the PanelDue log - around 8m I think was what the extruder stopped, so I have to wonder if this is in some way related to the WiFi reconnection. FWIW I rarely see that error, but it still seems like an unlikely connection.

I think next time it happens I'll again check the console log as well as check temperatures, but I don't recall temps being an issue. A faulty thermistor wire or heater wire could cause this, if the temp went too low and it stopped because of that, or if that happens and there's some latching. Or, an intermittent wire on the extruder motor itself (a PG35L) might stop motion, but it's been fine so far, and after one failure like this the next 2 5hr prints went fine. Or, it could be a software error.

Any other ideas for diagnostics to run next time this happens, besides the M122 report? I'd like to get some ideas before continuing to print. Thanks!

(edited to add ref to M122)

dc42

That's a strange problem. The usual suspects that would cause extrusion to stop - such as a hardware issue, or motor current getting set to zero, or extrusion factor getting set to zero, or a heater fault - would also prevent extrusion when you pause the print.

The factors that are stored separately for each GCode source are the feed rate, whether movement is absolute or relative, whether extrusion is absolute or relative, and whether volumetric extrusion is in use.

If your file was sliced using relative extrusion coordinates but somehow the firmware got into absolute extrusion mode, that would cause the extruder to move back and forth by small amounts, resulting in no extrusion after a little while. But in that case you would see the extruder making small back and forth movements, and I guess you didn't?

brandonh

@dc42 Yeah, I didn't see any extruder motion, both times, so I don't think that could be the cause. The first time the print had gone for about a half hour until I noticed, while the first time was only a few minutes.

whosrdaddy

This problem reminds me of this thread:

https://forum.duet3d.com/topic/3483/extruder-motor-stops-during-print

The crux of the problem was the fact there was static electricity generated by the spool holder causing problems with the extruder motor. Solution was to ground the extruder motor.

brandonh

@whosrdaddy said in Extruder sometimes cuts out in middle of long prints:

https://forum.duet3d.com/topic/3483/extruder-motor-stops-during-print

Thank you so much! tl; dr: I think I have the same issue.

The same problem happened again today 2 hrs in. Exact same symptoms as first two.

I'm using a PG35L too, like the D300VS in the link. My spool holder is a small vertical axis 2x-608 bearing PLA thing with a PTFE tube guiding the filament through to the frame; no PVC. Come to think of it, I don't think I've seen this issue before connecting the spool holder to the printer like it's connected now.

I'll see if a grounding wire fixes it and report back. Debug info below for posterity, but nothing that popped out:

9:32:29 PM
M906
Motor current (mA) - X:1000, Y:1000, Z:1000, E:450:450:450:450:450:450:450:450:450, idle factor 60%

9:30:33 PM
M122
=== Diagnostics ===
Used output buffers: 3 of 32 (10 max)
=== Platform ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 1.21 running on Duet WiFi 1.0 or 1.01
Board ID: 08D6M-95AK9-NG3SD-6JKDJ-3S46M-96R5X
Static ram used: 16152
Dynamic ram used: 100632
Recycled dynamic ram: 2000
Stack ram used: 1224 current, 7724 maximum
Never used ram: 4564
Last reset 02:28:23 ago, cause: software
Last software reset time unknown, reason: User, spinning module GCodes, available RAM 4432 bytes (slot 2)
Software reset code 0x0003 HFSR 0x00000000, CFSR 0x00000000, ICSR 0x0041f000, BFAR 0xe000ed38, SP 0xffffffff
Error status: 8
Free file entries: 9
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest block write time: 0.0ms
MCU temperature: min 26.5, current 27.0, max 28.7
Supply voltage: min 22.4, current 24.3, max 24.7, under voltage events: 0, over voltage events: 0
Driver 0: ok, SG min/max 0/323
Driver 1: open-load-B, SG min/max 0/357
Driver 2: ok, SG min/max 0/358
Driver 3: open-load-A open-load-B, SG min/max 0/1023
Driver 4: standstill, SG min/max not available
Date/time: 2018-05-07 21:30:32
Slowest main loop (seconds): 0.070072; fastest: 0.000046
=== Move ===
MaxReps: 30, StepErrors: 0, LaErrors: 0, FreeDm: 126, MinFreeDm 120, MaxWait: 4293730829ms, Underruns: 0, 0
Scheduled moves: 110300, completed moves: 110270
Bed compensation in use: none
Bed probe heights: 0.030 0.235 0.315 0.175 -0.006
=== Heat ===
Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1
Heater 0 is on, I-accum = 0.0
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 F1500" 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 1.21
WiFi MAC address 5c:cf:7f:2b:ea:77
WiFi Vcc 3.36, reset reason Turned on by main processor
WiFi flash size 4194304, free heap 15584
WiFi IP address 10.0.1.20
WiFi signal strength -57dBm, reconnections 0, sleep mode modem
Socket states: 2 0 0 0 0 0 0 0
=== Expansion ===

brandonh

@whosrdaddy said in Extruder sometimes cuts out in middle of long prints:

https://forum.duet3d.com/topic/3483/extruder-motor-stops-during-print

In 10 hrs of printing since adding grounding the extruder motor body (on a PG35L), with two prints, I haven't seen this issue recur yet. This isn't proof of a fix, but it's highly encouraging, since the MTBF seemed on the order of a few hours previously.

I used a wire that is tucked between the outer shell and the heatsink, and connected to the power supply ground.

Excited to be able to try other stuff now - updating to Duet firmware 2.0, trying out other slicers, etc!