Extrusion stops mid print  

Re: Extrusion stops mid print

Going to bring this threat back from the dead here as I am having the same problem.

I've been printing with a roll of PLA that has been doing exceptionally well at Prusa Slic3r default settings. We've used maybe a third of the roll so far without this kind of problem, and then suddenly, the extruder keeps notching the filament and getting it stuck. Here is what I've done so far:

Ive had about 4 prints in a row get about 1-2 hours in and fail because the notch in the filament stopped the extruder, and I can't figure it out. One of my hypothesis is that the extruder goes cold when I'm not around, halting the filament and creating the notch. Does anyone know of any evidence of this happening to a 3 month old printer?

Re: Extrusion stops mid print

This is happening with my mk2S too.

Have a sample of PLA that looks exactly like yours that I pulled out of the extruder on the last failed print - noticed 2 hours in which is a bit of a coincidence.

Like you I checked everything including stripping the hot end and checking for blockages etc. Found nothing, put it all back together re-calibrated and the print failed in pretty much the same place.

I marked the stepper shaft and the motor is definitely turning ok. I removed and checked the thermistor resistance and it matches the data sheet for the ambient temperature & tried moving the wires around to see if there is any intermittent connection issue and found none.

The wreckage from the failed print has lots of layer gaps indicating extrusion was becoming intermittent before it packed up completely. All the indications are the hot end temperature has dropped preventing extrusion. The LCD display was still showing 215 degrees. Before pulling the filament I tried to push it through the extruder and it wouldn't budge - given there was no blockage that as good as says the problem is the hot end temperature being wrong.

The temperature is regulated by a closed loop PID controller in the RAMBO. The thermistor resistance is converted to a temperature value and this is used to increase or decrease the average power delivered to the heater element and hence adjust the hot end temperature.

As the indicated temperature on the LCD was correct, this must mean the RAMBO is seeing (or thinks its seeing) the correct resistance for that temperature (from memory around 6 ohms - it was a few weeks ago and I don't have the exact value to hand).

As the temperature is actually low, it would indicate the reading is in error fooling the control loop into delivering less power than is actually required resulting in a cooler hot end than required.

Unfortunately this is where I have stopped in my investigation due to time. Having seen your post I now wonder if there is a common problem related to very long duration prints....

I still find it strange that after I removed the failed print and re-fed the filament, I could then print a small object with the same PLA on the same printer with the same settings without a problem. Kind of says if its a hardware problem its intermittent with time and now appears to be on more than on printer.

I'm planning on working on it further at the weekend, but would like to hear if others are having the same problem or, even better, have solved it?

Re: Extrusion stops mid print

I had a similar problem, but it not consistent like you both mention. My problem was with my first layer calibration. About 80% of the way through the calibration print, the filament stopped loading and had the same "notch" chewed into it by the extruder gear, coupled with a broken filament. It was a beast to get the broken filament out. However, once clear and cleaned, everything has been working fine. Everything fro 10 minute prints to 26 hour prints have been great. (Well, I had some layer separation/delamination with a 24 hour print, but that turned out to be a filament problem, not a printer problem).

One quick thing: the notch is not what is causing the problem, the notch is the result of filament getting stuck and the extruder gear chewing the notch into the filament. Not sure if this is what you were referring to or not.

Re: Extrusion stops mid print

I had similar issue. Here is my post. Is this a problem with the Heater/ thermistor?
A print stopped short and the next print would not extrude any PLA. I did a selftest which failed on Left Hot End Fan. When i raise the wire bundle to the hot end from the power supply the hotted the fan runs. There appears to be a broken wire in the Hot End fan. I is not visible but i can find the location by moving the wire. It is about 2 inch from the fan. I also get an error for the Heater/ thermistor which also comes and goes. I can not Load or Unload the PLA. No PLA exits when loading is attempted. The Wheel spins on the PLA. I have tried pushing and pulling the PLA when loading and Unloading. I have also try preheating at higher temperatures with no luck removing the PLA. Is the nozzle clogged or just not heating the PLA. Can i repair the Hot End or do i need to replace it along with the Hot end Fan? What is my next step the repair the Printer? What caused the problem and what can do to prevent form happing again. Any advice would be appreciated.

Re: Extrusion stops mid print

I've made some progress, and unfortunately have no good news. First, I may have left out some important info: I've constructed a hot box for my Prusa. I hadn't received a thermometer for it before this issue, but judging on the warmth of the plexi-glass, it wasn't getting to more than 40° Celsius. Second, this:
Extruder Motor Problem
I've followed their process to test both the fuse and the extruder motor cable. Both seem to be fine on my end. The coils are testing at 6.5 Ohms each, which, from some internet searching, seems perfect. The fuse is both intact and reading the correct resistance as well. However, our problems may not be the same problems, so this may be able to help one of you other users in this thread.

The temperature is regulated by a closed loop PID controller in the RAMBO. The thermistor resistance is converted to a temperature value and this is used to increase or decrease the average power delivered to the heater element and hence adjust the hot end temperature.

As the indicated temperature on the LCD was correct, this must mean the RAMBO is seeing (or thinks its seeing) the correct resistance for that temperature (from memory around 6 ohms - it was a few weeks ago and I don't have the exact value to hand).
I'm not confident enough in electronics to troubleshoot the RAMBO. I'm going to purchase another one, and another hot end. I'm going to have to play the swapping game until I find the culprit, and once I do I will have an electronics friend of mine delve deeper into the issue and I will post on the results.

Of course, the first thing that came to mind when Julian.P posted this was how PRUSA specified very clearly on how not to bind the thermistor wires, and I was careful to follow those instructions to a "T". I hope I don't have parts that have already worn out after only about 150 hours on the printer. It's a pain enough to have completely removed.

One quick thing: the notch is not what is causing the problem, the notch is the result of filament getting stuck and the extruder gear chewing the notch into the filament. Not sure if this is what you were referring to or not.
Donald.k6, if you were talking to me, I'm aware the notch is a symptom and not the cause. The notch indicates the filament has stopped moving. I'm diagnosing why the filament stopped moving only when the print reaches a certain time.

Re: Extrusion stops mid print

I've made some good progress

I've narrowed it down to the hot-end assembly. I ordered a new one and have it printing right now. It has made it past the 1 hour mark, which is where the last assembly would have already failed. My best guess is the thermister went bad somehow. I thought I would have gotten lucky, and noticed the thermister pole that inserts into the hot end was a bit corroded. I cleaned it with 600 grit sandpaper, and reinserted but that failed as well. Does anyone know how to test a thermister cable? I've heard of submersing it in boiling water for a time and taking periodic readings. I have a thermometer that connects to a K-type thermister, so I may try that later.

I'll keep you all posted.

Here is the hot-end I bought: https://e3d-online.com/v6 (1.75mm, With Bowden, 12v)

Re: Extrusion stops mid print

I have the same issue. My ABS prints are failing at a very consistent height. I increased the temperature of the head and got a few more millimeters before the extrusion stopped. Is there a fan setting I can fiddle to help with this?

[edit] I tried it again this morning even hotter, hot enough to see some side dribble, still jammed around 10mm high.

[2nd edit] I just successfully printed a different part for my assembly that is nearly 50mm tall with the same Slic3r settings. I have had six failures with the other part, fiddling with different variables.

Re: Extrusion stops mid print

I just want to share my bit about my issues and how I resolved them. For a while, I would either have to leave my enclosure open with the AC running, or I would have to make sure prints didn't run for a long time. Consistently I would have jams at near similar layer heights. For reference, this only occured with PLA. PETG and other materials that heated at a higher melting point did not experience this issues nearly as frequent.

What did I do to fix this? Well I did a few things. To preface this, I read through a lot of forums and tried a lot of work arounds without modding the printer. Then I started by replacing the PFTE tubing, insuring to have the end rounder off as described in the manual. Next, I disabled the filament sensor which unfortunately did not fix my issue as it seemed to fix somes.

What ultimately mitigated my issue was a combination of 2 things. The first thing I noticed was that the filament sensor would get very hot even to the touch. Sure, disabling would have fixed the issue completely, but I wanted the functionality. So I moved the 5v fan that is included in the printer to the top opening (originally mounted with zip ties - I am currently working on a part so this can be removed and reinstalled easier). Secondly, I installed a 12v Noctua fan where the old 5v fan on the left side was. I wired it like so: Direct connection to the 24v rail, which then was installed into a voltage stepper which stepped down the voltage to 12v, and then connected to the fan. This allowed for more air to flow over the "heat sink" (I am calling it a heat sink since the actual name for the tube is escaping me at the moment) which ultimately eliminated the heat creap issue.

Ever since doing these 2 (possibly 3, the PFTE tube might have contributed but I still experienced issues after that alone) simple modifications, I can report that I have had many successful prints that were not working prior. I used the same gcode files and everything, so these 2/3 things definitely helped a lot. Hopefully this will help someone else out, because believe me I was very frustrated with this.

Re: Extrusion stops mid print

Had the same issue but fixed it by re-aligning the extruder motor adapter and the spindle thing. I did it by removing the 2 screws with springs on them on the right side of the motor and untightening the adapter. Below is the picture of the 2 screws. Hope it helps!

RE: Extrusion stops mid print

Same problem on i3 MK3

Hi guys

I do have the exact same problem with my Prusa i3 MK3.
It started suddenly and since then I had no successful print anymore, which is very annoying.

From what I've read from this thread the problem could be resolved by replacing the Hotend assembly (at least for you, christopher-d8?):

I've made some good progress

I've narrowed it down to the hot-end assembly. I ordered a new one and have it printing right now. It has made it past the 1 hour mark, which is where the last assembly would have already failed. My best guess is the thermister went bad somehow. I thought I would have gotten lucky, and noticed the thermister pole that inserts into the hot end was a bit corroded. I cleaned it with 600 grit sandpaper, and reinserted but that failed as well. Does anyone know how to test a thermister cable? I've heard of submersing it in boiling water for a time and taking periodic readings. I have a thermometer that connects to a K-type thermister, so I may try that later.

I'll keep you all posted.

Here is the hot-end I bought:  https://e3d-online.com/v6  (1.75mm, With Bowden, 12v)

So to exclude this error I could theoretically use a Thermometer to check if the temperature at the extruder is correct? 

Did any of you had some more progress on this problem?

Really looking for your answers.

Best regards
Jonas

RE: Extrusion stops mid print

Posted by: christopher.d8

Here is the hot-end I bought: https://e3d-online.com/v6 (1.75mm, With Bowden, 12v)

Prusa uses direct drive, so the E3Dv6 12v without Bowden is the correct hot end for the MK2/S. Of course the Bowden tube can be repurposed into short lengths of PTFE - if it is the right diameters.