MakerGear Forum

Hi,

I thought I knew how to troubleshoot my printer, but I guess it that asked for troubles .

Short version: when I try to extrude the filament seems to "bunch up" inside the extruder guide and then get stuck (see picture). I verified that this is not a clogged head (problem repeats with new head).
Longer version:

I was traveling for more than a month, and so the printer did not work for a while. I came back and did few single-color prints (I have a dual head) without a problem. Yesterday I tried to print with the other extruder, and the print worked fine until mid way in a ~ 1.5 hr print.

When I came to check I found the head moving but not extruding. Stopping the print I didn't manage to retract the filament. I had to disassemble the extruder and found a nice dab of PTEG filament in the middle (similar to the pic above, but much worse). After clearing that up, I reassembled everything and set another print.

The second print got stuck at a similar stage of the print. I repeated the dis-assembly/reassembly, but this time decided to clean the head with eSUN cleaning filament. The filament would extrude a bit and then start coiling inside the extruder. If I stopped this in time I could retract. Otherwise, I had again stuck filament.

I went through this several time, different speeds and different setting of the extruder tension bolt. Eventually I decided that maybe the head is clogged. I replaced it with my spare one (another v4 head), and the problem repeated itself. I verified that the spare is not clogged by manually extruding through it without a problem.

I disassembled the extruder block and cleaned it thoroughly. The problem did not go away.

Other things I tried, I verified that the extruder tip is aligned with the head tube (not sure how you call this). Problem repeats also with ABS.

Ideas?

Thanks!

-Nir

Given the full explanation (and thanks for giving a full explanation, it helps a lot), I can guess what is happening based on at least one similar experience.

I think the hot-end is jamming, where a "jam" is better than a "clog" (not that there's any rigorous dictionary definition, mind you) because a jam is recoverable, and a clog requires you to take everything apart. In a jam, the filament is prevented from flowing, and eventually the extruder motor gear bites through the filament. If a jam is caught early on, you can retract the filament back out and start over without any problem. If left for too long, it won't retract out any more and you'll have to remove the filament drive to get it out.

PETg doesn't shrink as much as ABS, but it still suffers shrinkage, and prints that cover a large area of the bed, especially those that have long, straight vertical walls, can pull very forcibly off of the bed plate. I've had prints that would pull up several millimeters on one or more corners. When it pops, it rams the part up against the bottom of the nozzle, which is a good way to cause a jam.

The best way to prevent this is to print a very wide brim around the part to help keep it from warping. It will still likely warp and pull off the bed, but not nearly so much as when it's not firmly anchored. Printing on a raft may help, but also leaves open the possibility of having the raft warp and pull off of the bed. A single- or double-layer brim works better than a raft.

Tim wrote:Given the full explanation (and thanks for giving a full explanation, it helps a lot), I can guess what is happening based on at least one similar experience.

I think the hot-end is jamming, where a "jam" is better than a "clog" (not that there's any rigorous dictionary definition, mind you) because a jam is recoverable, and a clog requires you to take everything apart. In a jam, the filament is prevented from flowing, and eventually the extruder motor gear bites through the filament. If a jam is caught early on, you can retract the filament back out and start over without any problem. If left for too long, it won't retract out any more and you'll have to remove the filament drive to get it out.

PETg doesn't shrink as much as ABS, but it still suffers shrinkage, and prints that cover a large area of the bed, especially those that have long, straight vertical walls, can pull very forcibly off of the bed plate. I've had prints that would pull up several millimeters on one or more corners. When it pops, it rams the part up against the bottom of the nozzle, which is a good way to cause a jam.

The best way to prevent this is to print a very wide brim around the part to help keep it from warping. It will still likely warp and pull off the bed, but not nearly so much as when it's not firmly anchored. Printing on a raft may help, but also leaves open the possibility of having the raft warp and pull off of the bed. A single- or double-layer brim works better than a raft.

Tim, thanks for the reply. Indeed the initial problem started when the print got into long straight lines. I was planning to printing again with slower speed.

However, since then I replaced the whole head (hotend) and still cannot solve my problems. The new head did not get to print anything, it failed in the extrude stage.

Reduce the tension on the Filament Drive Screw. (Better yet, back the filament out and check the tooth marks. The bite needs to be under 15%.)

viewtopic.php?f=3&t=2694

And go sloooooooooow for PETG. (It do like to jam.)

nirfriedman wrote:Tim, thanks for the reply. Indeed the initial problem started when the print got into long straight lines. I was planning to printing again with slower speed.

However, since then I replaced the whole head (hotend) and still cannot solve my problems. The new head did not get to print anything, it failed in the extrude stage.

The same filament drive as before, or a new one?

Jules wrote:And go sloooooooooow for PETG. (It do like to jam.)

I print PETg at the same speed I print PLA. I have never had a PETg jam that was due to speed---it's always due to having the print lift off of the bed and press up against the nozzle. Maybe going slower alleviates that problem somehow? I've never tried it.

Jules wrote:Reduce the tension on the Filament Drive Screw. (Better yet, back the filament out and check the tooth marks. The bite needs to be under 15%.)

viewtopic.php?f=3&t=2694

And go sloooooooooow for PETG. (It do like to jam.)

Jules, I printed with settings that worked great with PETG for many prints (based on your great instructions).

Right now I got to a place where the filament get stuck regardless of the speed, screw tension, or type...

Tim wrote:

nirfriedman wrote:Tim, thanks for the reply. Indeed the initial problem started when the print got into long straight lines. I was planning to printing again with slower speed.

However, since then I replaced the whole head (hotend) and still cannot solve my problems. The new head did not get to print anything, it failed in the extrude stage.

The same filament drive as before, or a new one?

Same filament drive. I guess I can print a new one just to make sure. By visual inspection it looks fine (but maybe I am missing something).

nirfriedman wrote:Same filament drive. I guess I can print a new one just to make sure. By visual inspection it looks fine (but maybe I am missing something).

Maybe. Since it's a V4, you should be able to see the filament come out the bottom of the drive and go into the top of the hot-end. Is it getting that far? The most common place to get stuck is going into the hot-end, if the filament drive is out of alignment with the hot-end. If it's stuck in the filament drive, then there may be something there you can't see---but maybe try running filament through it a few times to make sure it goes through smoothy, before resorting to printing a new one. If it's getting into the hot-end and then getting stuck, and you're pretty sure the nozzle isn't clogged, then it's time to look at whether the heater is properly seated and the nozzle is getting up to temperature.

Tim wrote: Maybe. Since it's a V4, you should be able to see the filament come out the bottom of the drive and go into the top of the hot-end. Is it getting that far? The most common place to get stuck is going into the hot-end, if the filament drive is out of alignment with the hot-end. If it's stuck in the filament drive, then there may be something there you can't see---but maybe try running filament through it a few times to make sure it goes through smoothy, before resorting to printing a new one. If it's getting into the hot-end and then getting stuck, and you're pretty sure the nozzle isn't clogged, then it's time to look at whether the heater is properly seated and the nozzle is getting up to temperature.

Yes, the filament gets into the hot-end, and even extrudes a bit before jamming. When cleaning the drive, I run a filament through it to make sure the path is clear. "extruding" with the hotend removed works fine.

How do I check that the temperature is correct? Again, this problem repeated with two hotends - so two temp sensors. Is that a board problem?