Smoking hotend!!!

Discussion in 'E3D-v6 and Lite6' started by TheJimReaper, Jul 26, 2018.

  1. TheJimReaper

    TheJimReaper Member

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    Hi guys,

    Please bear with me with the long explanation of what I did, but could do with some advise on why this happened and what might have caused it.

    I've just replaced my V6 hotend with a new one, everything was printing perfectly, and had a really nice looking bottom half of a benchy. Then the filament snapped just before going through the filament detector which then did it's thing and paused the print. Changed the filament and set it going again. It stopped again before even printing again and spat the new filament out. I reinserted the filament, made sure some was coming out and set if off again. It printed half a layer and spat the filament out again! This time when I tried to insert the filament, it would only go so far into the hotend before it appeared to get stuck on something! So I pulled it out, trimmed the end again, and stuck the filament back in. Again it got stuck! So killed the print! Thought there maybe a clog of some sort so heated the nozzle, as the nozzle settled at 200°C we could smell burning, turned around to look at the printer and saw smoke coming from around the heat block and nozzle!!! Turned everything off and whilst it was still hot removed the bowden tube and put the unclogging needle down which went straight through but when it came back out a bit of stringy filament that hadn't melted came out with it!! Other that this little bit of stringy filament there didn't seem to be anything clogging the nozzle and I can't see anything around the hotend that would cause it to smoke. Everything was assembled per the E3D V6 assembly instruction, and did a PID tuning. The firmware is that I'm using is the TH3D one which I installed when I fitted the first V6 hotend back in May.

    Any ideas as to what I need to do would be appreciated.

    Thanks
     
  2. Old_Tafr

    Old_Tafr Well-Known Member

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    Lots of questions....

    The filament snapped? How? as it takes a lot to snap it when cold !

    When you changed the filament how did you do this? e.g. just push it through the heat sink into the heat break and heater block?
    OR
    Took the whole assembly apart and examine the insides?

    After a number of problems with filament jamming/not extruding a wrote a few posts on how I prepared the ptfe, and other parts of the hot-end assembly which can be found elsewhere in this forum, although Google gets much better search results that the inbuilt search engine here.

    The sort of things I found useful to concentrate on were...

    1. The way the ptfe is cut which can restrict the ID
    2. Removing the bend in the ptfe due to storage on a roll
    3. Slightly countersinking the end of the ptfe to allow entry of the filament

    A little more in this post...

    https://forum.e3d-online.com/threads/e3d-v6-wont-even-extrude-more-than-once-help.2753/
     
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  3. TheJimReaper

    TheJimReaper Member

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    Hi Old_Tafr Thanks for the reply and the help, it's much appreciated.

    Not sure how the filament snapped, all I can say is one end went through to the printer whilst the other end was left wrapped around the spool with the rest of the filament! I've had the the filament in question quite a while so I don't know whether it was already like that, or whether it's something to do with being sat in the back of a cupboard for about a year or so!

    Anyway, To answer your other questions, whenever I've changed filament I always trim the end at an angle and push it through until it starts pushing a little of the old filament out. Which is what I did this time and have never had a problem before doing it.

    I went through what you said about the ptfe tube above and in the other thread and in another thread I found you had posted to. The ptfe tube I have fitted is from the previous V6 hotend I had fitted. It's pretty straight, but I straightened it further, re-trimmed the end, and added a little countersink at the end the filament enters from.

    I also stripped everything down, cleaned all the little bits the previous filament had left behind and put it all back together.

    Before trying the same filament again, I tried printing with a regular one I use and although the benchy didn't print perfectly it did come out pretty nicely. So I currently have it printing something else, if all goes well overnight, I'll go back to the other filament and give that another go.

    Fingers crossed whatever it was that caused this has been corrected and other than adjusting my setting to improve print quality I'll be back in action, I've got a lot of catching up to done with printing.

    Thanks again for the help and advice, it is very much appreciated.
     
  4. Old_Tafr

    Old_Tafr Well-Known Member

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    Hope things are working well.

    A couple of other thoughts, E3D sent an Email a while ago mabe called "cold pull" although a search of Email does not find this. Searching Google on "E3D cold pull" does find quite a few articles including this from E3D themselves...

    https://e3d-online.dozuki.com/Wiki/V6_Troubleshooting

    which is well worth a read. It reminded me that there are a number of factors on getting the cooling right. Although E3D mention the duct they don't mention something I found after building my BigBox and having problems similar to yours.

    Specifically the blue fan shroud they supplied with the build kit is asymmetric, ........and fits either way up.......... the result being fitted the wrong way up it affects how much air flow there is towards the bottom of the heat sink, i.e. as you approach the heat break. I edited the BigBox WiKi to mention this.

    On the breaking filament; at one time I found that the filament was crossed on the spool and after a lot of pulling by the stepper motor against more and more resistance it pulled completely tight. I had to keep freeing up a yard or two to allow the print to continue. It has not happened again but it could happen particularly on a partly used spool where the loose end had been allowed to spring free and get mixed up with the coils on the spool. I had thought to build a serpent type series of spring loaded pulleys with a sensor to detect the filament pulling tight but it has not happened again.
     
  5. TheJimReaper

    TheJimReaper Member

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    Unfortunately I got up this morning to a thermal runaway error. So this morning I have be looking into ways of rescuing what had been printed so it doesn't go to waste.

    As far as the thermal runaway is concerned I think I know why. When I did the PID tuning I did it with only the heat sink fan running. I'm assuming having the part cooling fan running at it's usual running speed (30%) will also affect the temps. So I'm running that now, and we'll see how that works out.

    Thanks for the link, I'll give that a read.

    I'd be interested to hear how your pulley system with sensors works out, I had a recent experience with filament getting tangled and being pulled off the spool holder!
     
  6. Old_Tafr

    Old_Tafr Well-Known Member

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    From memory "Thermal Runaway" I and others had was too low a temp, just a confusing term in the firmware.

    The answer in a number of cases including mine was that the print cooling fan not the heat sink cooling fan, and quite likely nothing to do with PID (more in a mo on that).

    After my original and almost instant success with Benchy I tried a different print, result ........."thermal runaway"...........This was caused by the print cooling fan blowing on the heater block/nozzle. I had simply installed the fan as part of the build with no attempt to "position" it; (Why Bench worked no idea!) Moved this fan to not blow on the nozzle, problem went away; this is not unknown, in fact I think I was pointed at the solution here somewhere.

    PID Rusty on this but I'm sure the heat-sink fan has to be on but the print cooling fan is off. Heat-sink on is certain and it is defined in the firmware to come on at a set temp maybe 40oC? PID is best (must be) done in still air, my initial PID attempt was made with the window open on a nice sunny day, result PID was wrong. Tried again with windows and door closed in still air, success, I'm not the only one to find this, there was a post a few weeks ago on same subject and same cause of failure. Also remember to save the PID settings once you have entered them. Lots of posts on this with some initial mistakes but right in the end.
     
  7. TheJimReaper

    TheJimReaper Member

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    Yeah I've found that the Thermal runaways I been getting were due to the temps dropping, in some cases by 10+°C and staying there for a while before the firmware kicks in and kills the print. In other cases the temps have dropped drastically 30+°C and couldn't get the temp back up in time before shutdown.

    I'm using fangs for part cooling, which other than installing don't require any 'positioning'. They're the same fangs I used on the previous V6, and I didn't get any thermal runaway errors! I did think something similar to the 'air blowing onto the heater block/nozzle' where the airflow from the fangs could be 'bouncing' off the printing bed or part that's being printed and back onto the nozzle causing it to cool, but then I would have at this with the previous V6 as well!

    That leaves doing the PID tuning in still air. I don't know where your from, but with the hot weather we're having in the UK at the moment all our doors and windows are wide open, and we have an air con unit blowing cold air around the living room where my printer is located. This as with your experience could very well be causing the issue!

    I'll redo the PID with everything closed and turned off. Luckily today is a lot cooler, so I can get it done before my wife starts moaning she's too hot and needs everything opening and the air con back on!!
     
  8. TheJimReaper

    TheJimReaper Member

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    Right just got back and redone the PID, there wasn't much difference between the earlier figures for the P and I, about 2.8 higher for the P, 0.01 for I, but the D was 16 higher.

    I'll do another print and see what happens.
     
  9. TheJimReaper

    TheJimReaper Member

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    Well I didn't get round to do the print until this morning, and I'm doing nothing but bang my head against the wall!! I started a print off, heated up fine, got halfway through the first layer and filament stopped coming out! With the LCD screen saying the temp of the nozzle was 210 my first thought was I was maybe back to my first problem that started this whole thing off. However, after stopping the print and heating the nozzle so I could check for clogs, the filament started to slowly come out of the nozzle, so no clogs and after extruding a little everything seemed fine.

    No, my problem now is the nozzle won't heat up!! If I unplug the heater cartridge and plug it back in then it will heat up, which tells me it could be a loose connection. Could this have been the issue all along?

    Going back to the PID tuning once again. I've been using the command M303 E0 S210 C8 as in the assembly instructions it says "Typically you will use" and the results have all been around P32.89 I2.61 and D87.7 until I did it again with the doors and windows shut and the AC turned off the D went up to 103.07. P and I only varied a small amount.
    I did another PID this morning, when this mornings problems started. However this morning, I can't explain why, I just used the M303 command and it ran the PID with the nozzle at 150°C instead of 210. And as expected the results were completely different.

    So which command do I use for the PID tuning?
     
  10. Old_Tafr

    Old_Tafr Well-Known Member

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    Have a look at this post...

    "https://forum.e3d-online.com/threads/pid-tuning.731/"

    Which has a lot of good info on PID including...

    One further point here for those with a Dual. Each hot end might require different PID tuning. Tune each PID with

    M303 E0 S230 C8

    and

    M303 E1 S230 C8

    There are a bunch more posts on PID try a Google or Duckduckgo search on "e3d forum PID tuning"

    ==========================================================================================

    All the leads leading to the extruder....

    • Fan connections
    • Temperature sensor
    • Heater

    Are prone to wear and tear in normal use, more so when it comes to hotend maintenance where there is considerable risk of damaging the wiring when dismantling/reassembling especially where it enters the heater or sensor. Intermittent connections are going to be a LOT less noticeable for say a heater (30 watt or 40 watts? the lower may have trouble keeping up regardless of bad connections)

    I had hoped a separate part of the WiKi would be a ref for particular info and problems, this never happened, in effect the forum needs an index!

    In lieu of that you need a list of electrically connected items like the various heaters temperature sensors etc. and the resistance value to expect. Again a host of posts on this forum just needs a little searching. For measurements a good digital meter is better in this case than an analogue one.

    There are a number of posts on adding connectors to the various wires............. fan, heater and temp sensor.........(take care some of the RS component part numbers are wrong) ... also now some of these come new from E3D with connectors. This makes maintenance much easier as you can just disconnect everything to then take the heat sink heat break etc apart.

    What I'm saying here is that it is quite possible that the heater has a bad connection and the first check is to remove the connections from the controller and check the resistance.
     

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