PLA Suddenly Jamming Mid-Print

[Ryuluce]

I recently switched back to using PLA after I got tired of trying to use ABS (warping, de-lamination, et cetera) and I've started having issues with jamming.
My printer is the QIDI Tech (the version with the ATMEGA128 controlling chip) that has been re-flashed with Sailfish ver. 7.1.
The slicer is use is Slic3r.

So, this is what happens:

I load the filament in normally and without issue first. The filament during the loading extrudes out without any evident obstruction.
I then try to print a test piece ( http://www.thingiverse.com/thing:342198 this to be exact) and the HIPS/PLA start without problem. (the little test line at the start is smooth and clean)
I leave the print, and when I check on it halfway through I find that the PLA has stopped extruding.

Above is a picture of the failed print, see how the extrusion became wispy. By the point I had noticed, the printer wasn't extruding at all.
This was actually my third attempt with this print, the first one I stopped to modify some settings, and the second one jammed in a similar fashion (the build plate was also poorly leveled during the second print, which I fixed for the third).

Above is a picture of the first print (still on its HIPS raft). See how much better the print is.
The only difference between this print and the third one's settings is the fact that I turned on the filament cooling fan (as far as I can remember).

Above are pictures of the filament I pulled out of the printer after the jam.

This link is to a ZIP file containing all the pictures of the prints and the removed filament: https://www.dropbox.com/s/95glrp2yg5...shoot.zip?dl=0
This link is to a .ini config bundle file for Slic3r which contains my current settings for PLA: https://www.dropbox.com/s/f2v88z6kbe...onfig.ini?dl=0
In the configuration bundle, untitled is for the PLA and untitled 2 is for the HIPS.

[Labbo1979]

I found this article about jammed extruders mid print and how to save em.. Maybe it helps? https://3dprinterchat.com/2016/05/ex...ow-to-save-it/

[Ryuluce]

I found this article about jammed extruders mid print and how to save em.. Maybe it helps? https://3dprinterchat.com/2016/05/ex...ow-to-save-it/

I'm afraid that that article didn't provide much help. I tested some of its theories, but I am still having clogging issues.

Also worth noting: I tried printing at 190c, 200c, 210c, and 220c. I still had clogging at various layers.

[Ryuluce]

An update on what I've tried:

I took off the nozzle and cleaned it out using physical methods (I didn't do a chemical bath).

I also tried resetting the extrusion widths in the advanced print settings, but that didn't seem to help.

[Geoff]

An update on what I've tried:

I took off the nozzle and cleaned it out using physical methods (I didn't do a chemical bath).

I also tried resetting the extrusion widths in the advanced print settings, but that didn't seem to help.

I think it's the filament I'm afraid to say. PLA absorbs moisture rediculously fast, there is a slight fat section that won't go down the extruder pipe and gets blocked at the top, while the hobbed gear just keeps pulling away at it. See how you have that long stretched section? your PLA was a bit gooey and there was a bubble in it it got caught and the rest kept getting pulled down until it lost extrusion and stops spitting out plastic.

The fact it's pulling it tells me that the problem is on the top end, not the bottom end. If it was some old ABS stuck in there, you would just get a grind out and the filament would get blocked and you hear "click click click click" from the stepper motor. In this case, its not a problem of going into the pipe, it's a problem of a bulge in your PLA that won't go down the very first hole it needs to go into, the holy just above the hobbed gear.

[Ryuluce]

I think it's the filament I'm afraid to say. PLA absorbs moisture rediculously fast, there is a slight fat section that won't go down the extruder pipe and gets blocked at the top, while the hobbed gear just keeps pulling away at it. See how you have that long stretched section? your PLA was a bit gooey and there was a bubble in it it got caught and the rest kept getting pulled down until it lost extrusion and stops spitting out plastic.

The fact it's pulling it tells me that the problem is on the top end, not the bottom end. If it was some old ABS stuck in there, you would just get a grind out and the filament would get blocked and you hear "click click click click" from the stepper motor. In this case, its not a problem of going into the pipe, it's a problem of a bulge in your PLA that won't go down the very first hole it needs to go into, the holy just above the hobbed gear.

Hmm. That'd suck if that's the issue. Are there some good ways to test if that is definitely the problem? I don't have "popping" which I've heard is a common symptom of PLA hydration.

Though, I wouldn't be surprised if the moisture is the cause, because I do live in a fairly humid environment. But I was using the PLA before I started using ABS and it was working quite well for at least over a month without any special containment. Although, that was during the winter and subsequently a drier part of the year.

I just want to isolate if that is absolutely the cause, since that will allow me to more directly address the problem.

By the way, what do you mean by "pulling"? If you're referring to how stretched the filament is, I think that's because of how I pulled out the filament when I was removing the blockage. Most other times I removed the filament, it wasn't like that.

[Ryuluce]

So, I've got some more footage and pictures to show about the printer.

First:

As I said, the filament would extrude without trouble when I load it.

Above is a video of the printer extruding PLA when I ran the load filament script.

The pictures above are of the extruded filament.

Second:

I decided to try a print so I could take photos of the jammed extruder from the inside.
Note: The first several layers printed without any trouble and very cleanly. Also, it seems that the printer jams when printing the infill, not the perimeters.

Above are photos of the inside of the extruder after jamming.

Here is the end of the filament after I ran the unload script and removed it.

Above is a photo of the incomplete print still on the bed.

Again, here's a link to a ZIP containing all the pictures in higher resolution: https://www.dropbox.com/s/aofvk4gja2...t%202.zip?dl=0

[Ryuluce]

So, since I hadn't gotten any responses to this problem in a long time, I decided to try recording an entire print up until the point of jamming.

(I'm sorry for the relatively poor quality)
The video above is timelapsed during the majority of the print for time's sake. If anyone wants, I can provide an unedited video of the print. Be warned, it's over an hour long.
I forgot to photograph the filament after removing it, but it looked fairly similar to the removed filament in my last post, except there was no small bend in the filament near where it was in the hot end.

[Alibert]

Is the heatbreak/throat PTFE lined or an all-metal one?

[Ryuluce]

Is the heatbreak/throat PTFE lined or an all-metal one?

PTFE lined. I actually fairly recently replaced the PTFE lining with a spare that came with the printer.

BUT, this is the more important part: I actually got a print to finish!
The print is soaking at the time of writing in limonene to remove the HIPS.

Here's what I did that made it (I think) work: I turned off the direct filament cooling.
So far, my theory is that the cooling apparatus was cooling the nozzle of the PLA extruder making the gear grind down the filament.
I plan to upload photos of the print when the support material is done. I haven't gotten a second print done yet to make sure it was not a fluke yet because I was having some trouble getting the PLA to stick to the raft of this other test print. I don't have the time to mess with it at the time of writing, but I'll likely give it another shot after some tweaking tomorrow.