Another heat creep jam problem  

Re: Another heat creep jam problem

have a look in this thread:

https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f64/getting-jams-caused-by-what-i-think-may-be-heat-cr-t23708.html

there are a lot of ideas there.

My solution was some thermal paste on the thread of the heatbreak, like in the e3d assembly instructions:

https://e3d-online.dozuki.com/Guide/V6 + ... ang=en#s76

Step 15

Re: Another heat creep jam problem

Thanks. I have gone through pretty much everything in that other thread, short of completely dismantling the hot end, which I guess I'll be doing soon. I agree that thermal paste is important, but does it suddenly fail? This printer has been running flawlessly for hundreds of hours.

Oh well, I guess I'll take it apart as soon as I get time.

Re: Another heat creep jam problem

Thanks. I have gone through pretty much everything in that other thread, short of completely dismantling the hot end, which I guess I'll be doing soon. I agree that thermal paste is important, but does it suddenly fail? This printer has been running flawlessly for hundreds of hours.

Oh well, I guess I'll take it apart as soon as I get time.

It was the same for me. I got one jam out of the blue and nothing worked after that until i used the thermal paste. And Prusa changed the Parts in R3 to improve the cooling of the cold end. So it seems that the noctua fan might be a little on the weak side.

Re: Another heat creep jam problem

Okay, it's been a couple of weeks. Here's everything I've tried.
- installed the R3 extruder
- swapped back to the original part cooling shroud
- replaced the PTFE tube with a capricorn tube, properly prepped with 30 degree bevel and reamed entry way
- added a collet clip to prevent the tube from moving
- increased print temp by 10 degrees
- loosened bondtech tension screws
- added new thermal compound
- added a silicone sock on heater block
- increased temp another 5 degrees

After each change, I attempted to print the sample benchy file that came with the printer, that I've printed many times with no problem. Most attempts failed at less than 10%. A couple went more than 50%, but all failed. Eventually, the nozzle clogs and it stops putting out plastic. To remedy, I just have to stop the print, preheat the nozzle, unload the filament, clip the little knob off the end of the filament, then reload. Works every time.

So what is going on here? I've changed everything I can think of. The only other symptom is that the extruder is getting really really hot. I guess I could put a fan or heatsink on it.

This was my favorite, go-to printer for everything, and now it can't print anything and I can't figure out why!

Re: Another heat creep jam problem

Have you tried replacing the nozzle with a brand new one? I'm just spitballing here, since it looks like you've tried a lot of things that haven't worked so far. Maybe there's some crud or wear on your nozzle that's causing intermittent clogs and isn't being removed by cleaning.

Re: Another heat creep jam problem

I ordered a new nozzle and heat break. I'll give them a try when they come in if I haven't resolved the problem. I am going to mount a blower fan (like the part cooling fan) in place of the noctua and see if that has any effect. I measured the speed of the noctua and it's turning at 4500 rpm, which I believe is its rated speed, but I want to see if a stronger fan might cool the heatsink better.

Re: Another heat creep jam problem

So I mounted a blower fan in place of the noctua. The first test print failed like the others, although a little later into the print (~70%). I kicked off another print, this time increasing the nozzle temp after the first layer to 230c, which is +20 over the original (I'm still using the benchy example file that came with the printer).

The printer just finished producing a perfect benchy.

Is there something that could have changed the temperature sensor calibration? I've had a couple of different cooling fan shrouds on it - currently have the original mk3 style on there - and I also have a sock on the heat block so I don't think it's the fan affecting the heat. It seems like the temperature is off by 20c.

Any ideas on what's going on here? I'm going to go back to the noctua fan and increase the temps and try another print for now.

Re: Another heat creep jam problem

Hi,
i got the same problem/issue, that it seems that my "real" temperature is round about 20 degree lower than displayed.

Any ideas?

Re: Another heat creep jam problem

I have the same problem. Though, I first thought it had to do with to high extruder motor temperatures. I was able to lower the motor temperatures a bit and it seems I don't have bolten PLA jams right at the entry to the PTFE tube going towards the hot-end. But I do have jams now what seems like in the heat-breaker / hot-end (not in the nozzle).

0.25mm nozzle :
So I stepped the game up a notch and installed the 0.25mm nozzle and set off to print some small DND characters.
I was amazed by the detail you can get! But I started to have problems again with printing. Specially when printing multiple characters in one go.

On thing I noticed is that when pulling out the jammed filament it did not grind the filament, and you could hear the motor stepping. It has perfect grip without grinding out the filament. Also when I would cut of the end of the pulled out filament and reload it again it would directly load without problems or jams. So the nozzle itself doesn't seem to get jammed with something. I inspected the pulled out filament pieces and noticed they all had a rather large bigger diameter chunk.

It almost seems like the filament is not getting liquid enough anymore to get pushed through the 0.25mm nozzle and starts to collect in the heating chamber. I tried to increase the temp from 210 to 220. It would print a bit longer in general but still get stuck. This all is with the prusa filament it came with (lovely silver for detailed DND character prints btw!)

So I started to think again it could be the filament, but it also printed fine a few day's ago... so that would be kinda strange.
I now have an other theory what might be the problem. My printing environment now is a bit high on humidity (61%). So it could be the filament cought up to much water? I opened a fresh spool of colorfabb PLA white. First print went perfect! See also the picture above, the white filament doesn't build up as much as the silver one.

Humidity test :
So I will try out an spool drying trick with the prusa PLA silver spool and see if that solves the problems I have with that spool.
Yesterday I put the gray filament in the oven @50C for a few hours (~3). Started the print again. But this morning (~12 hours in the print) it jammed again. I also see no noticeable difference, maybe a bit less stringy. Pulling the filament out it has an other one of those bigger diameter tips (like on the photo's before. And the nozzle itself oozed out fully. When loading white filament it directly started extruding white.

So, putting the filament in the oven and reducing the water % in the filament did not help with it getting stuck. I think the silver prusa filament is just not that good for 0.25mm nozzles. And might contribute to hotter motor's since it will create an growing half molten blob on the end of the filament that it needs try to move to the point where it causes so much friction that it won't move down enough anymore to be molten again.

Again a blocking tip, nozzle oozed out fully as can be seen direct extruding white as I loaded white filament (only little dot of gray at the start).

Re: Another heat creep jam problem

Here is another update on my jamming problem. In my last update, I mentioned that I was going to try going back to the noctua fan while using the increased temps. That did not work, it still jammed. So I reinstalled the radial fan for the heat sink cooling and used it that way for a couple of weeks, which worked fine, as long as I used increased temps.

A couple of days ago I replaced the nozzle and heat break. The nozzle is a genuine E3D and the heat break is a micro swiss, both high quality pieces. I'm still having to use increased temps, but I have at least been able to go back to the noctua fan.

Since the problem seems to be that the temperature is reading too low, it seems that the only causes left are a faulty thermistor or the Einsy board. I've ordered a new genuine E3D thermistor and will give it a try when it comes in.

Re: Another heat creep jam problem

Here is another update on my jamming problem. In my last update, I mentioned that I was going to try going back to the noctua fan while using the increased temps. That did not work, it still jammed. So I reinstalled the radial fan for the heat sink cooling and used it that way for a couple of weeks, which worked fine, as long as I used increased temps.

A couple of days ago I replaced the nozzle and heat break. The nozzle is a genuine E3D and the heat break is a micro swiss, both high quality pieces. I'm still having to use increased temps, but I have at least been able to go back to the noctua fan.

Since the problem seems to be that the temperature is reading too low, it seems that the only causes left are a faulty thermistor or the Einsy board. I've ordered a new genuine E3D thermistor and will give it a try when it comes in.

Thanks Karl.t
Keep us updated on your findings.

Re: Another heat creep jam problem

I got the same problem. Recently all long print fail after perhaps 7-8 hours. first time this happen I had a 18 hour print and it failed after 16 hour.
Cut the gcode and started the print for a nice top. I missed a bit on the Z height, so i popped off the top part and started again with spot on Z height for a print part 2. It then suddenly failed after an hour ruining my print.
I suspected my Octoprint, so i sliced again and loaded on a sd card where I also increased the speed a bit and reduced infill to speed up the print. This also failed around 50% in the print like the previous.
Print up to the fail are "flawless" and look great, so it is really painfull to come home and see the printer just moving in the air without flow.
I could warm up, unload and clip the end and then load to make another print without any issues. The flow are a bit clogged at first where the filament curl up to the nozzle while extruding, but this is gone after 4-5 loading sequences.
I have replaced heating block, heat break, thermistor and heat element since I had a bad case of clog earlier where my wires broke for the heating element.

Re: Another heat creep jam problem

I want to add my comment here, I am experiencing what seems to be the exact same problem... perfect prints out of the box, and then a sudden increase in failures where benchy prints fine until it reaches the deck level and starts making retractions, after which it under-extrudes with all signs pointing to heat creep, eventually jamming if the print isn't stopped. I am going to try turning up my temperatures and seeing what happens.

Re: Another heat creep jam problem

Could it be a break in the hot end wiring?, try positioning the benchy on different sides of the bed (Left and Right) and see if there is any difference.

Re: Another heat creep jam problem

Hi,

I have been having the same issue. Did you ever find a solution? This is not the only post I found about this issue but after trying the stuff listed in my post on this topic: https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f64/printer-jamming-clicking-sound-after-a-while-print-t27344.html I am at my wits end.

Re: Another heat creep jam problem

I received my MK3 early last year in March, and I was pretty active here for awhile trying to troubleshoot problems like the people in this thread are having. I ended up having to replace my entire hotend with official parts from PRUSA once, which worked for a few weeks then I got the same problems again, and I didn't want to spend over $35 on shipping again just to have the same thing happen. Even my Bowden tube was melted and deformed, my extruder motor was constantly overheating, and I was getting jams very similar to the photos I've seen in this thread.

I tried a LOT of things. I ended up installing a new heatbreak and nozzle from microswiss as well as new Capricorn PTFE bowden tubing rather than what Prusa uses, getting a special cutter to make sure the bowden tube cuts were as straight as humanly possible. This still didn't solve my issue. I also installed a stainless steel nozzle made for specialty filaments just to be able to print PLA without clogging often. I took apart and rebuilt and recalibrated the extruder assembly dozens of times, spending days just working on my MK3 trying to get an even print without clogs. I resorted to using ceramic thermal paste to attach a raspberry pi heatsink to my extruder motor in an effort to keep it cool.

After that nightmare I broke down and bought a Dremel printer just so I could fill order for the 3D printed things I sell and not have to deal with out of country customer support with high shipping prices and slow response times for official support (However, this forum was very helpful in offering possible solutions, without this forum I would have truly given up on my Prusa Printer a long time ago)

Around 3 months ago I decided to give my MK3 another chance, I updated to the newest firmware and miraculously it's been running fine ever since, except in one certain situation, where I think part of the problem lies. That situation is when the nozzle has to pass over several centimeters of detailed ridges as the extruder moves to the next layer. There seems to be a few micrometers of space where the nozzle will grind against large areas of detailed parts (not infill, but printing something with a lot of small protrusions and flat space like a textured phone case). This only occurs on certain prints with a lot of flat space and finely textured areas, like printing a lithophane of a photograph (something I like to make in Cura).

I can't say for certain how my printer suddenly got over the terrible months-long plague of issues that almost killed my interest in 3D printing, but I know the most recent changes were the firmware upgrade, new Capricorn bowden tubing, and new steel nozzle. I know the firmware changes did something to the motor power which solved my extruder motor heating issues, combined with the new bowden tubing, heatbreak, and nozzle where likely what finally fixed most of my heat creep jamming issues.

Re: Another heat creep jam problem

Just wanted to add something I know / found out about fans. It seems many people are trying to swap the standard fan (40x40x10mm) for a thicker version (40x40x20mm) and are reconstructing their whole extruder assembly for that purpose.
But such a fan is not necessarily better. The critical value in case of the heatsink fan is not the cfm or m³/h which indicate the moved air volume, but rather the static pressure, usually given in mmH2O or InH2O. As other forum users might have explained already, this value indicates the ability of a fan to push air through an obstacle.
The standard fan used by the Prusa i3 Mk3 is a Noctua NF-A4x10 5V which has a static pressure of 1,78 mmH2O at 4500rpm.
After searching a bit I found a fan from Panasonic which claims to move about the same amount of air but with a pressure of 3.47 mmH2O at 5500rpm with the same dimensions! 😮
The higher speed surely raises the noise level a bit, but that's not an issue for everyone. I haven't tried this fan yet myself - partly because it's not cheap - but as my Mk3 sometimes suffers from probably heatcreep related jams too, I'm thinking about giving it a try.
Keep in mind that if you swap a fan, it has to have the same nominal voltage (5V in this case) as the original one.

Re: Another heat creep jam problem

Were there any updates for this? I just started having the same issues with Clear PLA from Fillamentum.

I've replaced the PTFE tube, checked the gears, tried slower, faster, hotter, cooler and the jam only happens after a lot of retractions then I have to unload, snip and reload and it prints fine for a bit.

Re: Another heat creep jam problem

The images of the cold pulls don't look very convincing. Also looks like the tension on the drive gear is a bit on the high side (tooth marks are extreme).

Common issues 1: small nozzle and fancy filament usually non-compatible. 2: filament has a particle in it smaller than 1.75mm but larger than nozzle: sometime metal, sometimes a different plasitc with a high melt point. 3: debris in the heat break compacts and jams filament. Requires nozzle removal and airing out the heat break filament path.