Why is my extruder suddenly retracting/extruding a ton of filament?

Got a strange problem with my home-built Prusa i3 with Sanguinololu running Marlin. I've had this problem for a long time, but it doesn't happen very often. Basically in the middle of a print, the extruder will suddenly retract at high speed for a few seconds or sometimes extrude. The result is that either the filament is ejected out of the extruder, or I get a blob of plastic in the middle of my print.

At first, I suspected this issue might have been due to a dodgy SD card, so every time I printed, I used to format the card before hand and this seemed to have avoided the issue. A few days ago, I decided to finally check the SD card and used the free software h2testw (http://sosfakeflash.wordpress.com/h2testw/) to check if the SD card was working fine and it passed successfully. So, I stopped formatting the card before every print and just put new gcode files on. This has worked for for several prints now, except the last one yesterday which was an 8 hour print (typical) that failed half-way through because it ejected the filament.

So I'm not really sure what's up here. Is there a bug in Marlin (If it is, it's been present both in the latest version I downloaded and compiled yesterday and the old one I've been using for months and months)? Does Marlin have a problem when the SD card has several files in it? Is it a hardware issue? Is it the slicer (Cura)? Could it be the controller board?

Anyone come across this problem before? Any thoughts?

Amr

Edited 1 time(s). Last edit at 11/26/2014 11:47AM by amrbekhit.

Here's a video of it happening again:

[youtu.be]

In the description I've included links to the times of the various problems. At the beginning you can see the extruder suddenly retract all the filament out at high speed. It then proceeds to move for a bit and the extruder stops moving for a period of time.

I've uploaded the gcode file here:

[drive.google.com]

I extracted all the Extruder values and plotted them using DatPlot (fantastic software btw!), but couldn't see anything particularly obvious.

Any thoughts?

Edited 1 time(s). Last edit at 11/26/2014 06:37PM by amrbekhit.

I couldn't get in to the gcode, permission problem. I've had that happen a few times, but mine is always at the beginning of the print. I would guess it is a slicing thing. When it happens try reslicing and see if it continues, if it does then I would suggest reloading firmware.

Ok quick update: I checked the gcode using the fantastic gcode.ws site, and there was nothing apparently wrong. I've tried two different SD cards, reslicing, updating Marlin to the latest version but to no avail.

In the end, I installed Repetier Firmware, got it set up for my printer and then printed the same gcode file from the same SD card without any problems.

So in summary, I could only conclude that this is a long running issue with Marlin that has transcended version updates, and it seems that Repetier doesn't have this problem, and I've managed to get my print to complete successfully.

I'm also having the same problem on my i3 + Ramps 1.4

Anyone here to address this on the Marlin Firmware, Yes it happens exactly. the symptoms are exactly the same.

Any Help shall be much appreciated.

My suggestion is to just use Repetier Firmware. I've been using it for several months now with no problem. It does the job just fine, and I don't need to worry about dodgy print issues.

Will it be possible to share the Working Repeitier FW via Drop Box, I will change my parameters, Im frustrated, Does not want to take a chance again.

Much appreciated.

Did you use slic3r? I've seen strange behavior in files produced by slic3r even though the gcode looks OK, the printer does some crazy things.
Slic3r has some sort of instability that will occasionally cause it to do weird things- I don't know if some windows or library updates are breaking it or some other problem, but it has behaved this way for a couple years. Signs of problems include slic3r ignoring changes to printer/filament/machine settings (save them and the newly entered value is gone), very long slicing times, and weird printer behavior such as the extruder moving away from the print then moving back even though gcode viewers do not show that in the gcode. When it misbehaves the only thing I've found that helps is to reinstall (sort of like windows!). It seems to work most reliably when compiled from source code under linux.

yes slicr3 on windows, i will try your suggestion.

This can happen when you have your slicing program set to use absolute extrusion coordinates, but your printer is set to use relative extrusion coordinates. See the M82 and M83 commands in [reprap.org], and the "Use relative E distances" checkbox in the slic3r printer settings.

Edited 1 time(s). Last edit at 04/19/2015 03:41AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

One more confirmation, is I had a successful 8 Hrs print via PC, and this behaviour happens only via LCD Controller. So something to do with LCD and Firmware.