[Solved] Original E3D v6 Randomly Skipping

Discussion in 'E3D-v6 and Lite6' started by Thorinair, Aug 14, 2017.

  1. Thorinair

    Thorinair Member

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    Okay, so I guess I am getting a bit annoying with these help threads, but this is getting a bit out of hand.

    So, I assembled my bowden setup with the original E3D v6 hot end, and I am getting seemingly random skips on my extruder motor. Not skipping in the hob, but completely skipping steps (going back like half of a turn), The image below shows my printer along with some images of the hot end setup.

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    I've originally used a different hot end mount which I thought didn't allow for enough air circulation, but that doesn't appear to be my issue.

    Here are the symptoms:
    • The extruder motor will seemingly randomly skip steps, probably half a turn, but hard to measure, moving backwards as the filament bounces back.
    • It doesn't matter if I print stuff which has a lot of retraction or no retraction at all.
    • It doesn't matter which temperature I print on, getting exactly the same amount of skips on 190 and 210 °C.
    • The skips sometimes get worse with time and then suddenly stop, just to return half an hour later.
    • I am printing PLA, specifically Devil Design's black PLA.
    Here is a full list of things I tried and verified:
    • The cooler fan blows inwards towards the heat sink and is plugged into the always on port on my mainboard. I used a multimeter to verify that it always gives 12V.
    • There is plenty of airflow space for the fan to blow the air in and out.
    • The heat sink is only slightly warm to the touch. The top (where the bowden tube enters) reads around 32 °C on my IR thermometer, and the body around 40 °C.
    • The hot end is properly assembled, with plenty of thermal paste used and the heat break tightly screwed into the heat sink.
    • There is enough pressure in the bowden extruder. The motor itself skips, not the hobbed gear (using an original E3D hob).
    I also tried to do the cold pull. I heated it up to 210 °C, lowered the temperature the 80 °C and kept pushing the filament through as it was cooling. Once at 80, I tried to pull. Nothing was happening, so I kept upping the temperature by 10 °C, and went up to 140 still without any success. Had red marks on my fingers at this point from all the pulling. When I tried to print again, I found the hot end to be completely clogged.with practically zero extrusion. I tried to up the temperature to 230 °C, pushed it with motor, heard a loud snap and then it started extruding again. Maybe this helps diagnose the issue.

    Honestly, I am completely lost. My printer is effectively useless right now, and I don't know what to do to fix this. I bought the original because people said they had jamming issues only with clones. If anyone has any ideas or advice, I am willing to listen. I heard that some people add canola oil?
     
  2. Antoine

    Antoine Well-Known Member
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    Can I ask what speeds you are printing at? This sounds like your motor is struggling, not the hotend. Check the voltage.
    You can also print PLA at up to 220°C with the V6. As it is not PTFE lined, you get slightly more resistance compared to PTFE hotends.
    You might also want to check your bed levelling. If the nozzle is too close to the bed on the first layer, your plastic will have difficulties getting out of the hotend.
    The accelerations might cause this issue. I would also advise to slow everything down until it works and progressively increase the speed. This might help you isolate the cause of the skipping issue.
     
  3. Thorinair

    Thorinair Member

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    • Motor is struggling, just as much as my hand is. Increasing the current won't help here as the motor is already very warm. Pushing it manually with my hand doesn't help at all, the jumps back feel extremely violent, making the whole printer shake.
    • I am printing relatively slowly already, 32 mm/s outer parts, 48 mm/s inner parts. I can push the filament out of the hot end at 4x that speed with no clogs at all. Except for the same random skips that happen every now and then.
    • The clogs don't happen on the first layer, only later on during the print. There are no bed leveling issues. Check the image below for the shiny first layer.
    • The accelerations I am using are 400 mm/s2 on both X and Y with 200 mm/s2 starting acceleration (in Marlin firmware), 1000 mm/s2 for the extruder. Jerk is set to 8 mm/s3.
    • At 210 °C, I already get very ugly results because it is too warm for the filament I am using. 200 °C seems like the sweet spot, and 190 °C gives it a nice matte finish.
    EDIT: Forgot to mention that the skips usually happen more on long continuous extrusions.

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    #3 Thorinair, Aug 15, 2017
    Last edited: Aug 15, 2017
  4. Ephemeris

    Ephemeris Well-Known Member

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    "the skips usually happen more on long continuous extrusions."

    That sounds like over-extrusion. This is especially bad on layer one. If you command it to push out more plastic than there is room for it to go, something has to give. When they hydraulic pressure gets high enough, either you strip the filament, or the stepper will rotate backwards a bit.

    Try reducing your extrusion multiplier and see if the problem becomes less pronounced.
     
  5. Thorinair

    Thorinair Member

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    I already calibrated my extrusion rate. Any lower than current, which is exactly 100%, and I get holes on top layers of my prints. I also calibrated the extruder's steps before trying out different multipliers. Also, if I can push out 4x more volume of filament over same period of time with no problems, why would this be related to overextrusion?

    To me, this whole thing stinks of PLA getting sticky and stuck on the walls of the all-metal hot end. I've read plenty of threads where people suggest using something like canola oil (or any other vegetable oil which has a high enough smoking point) and using an oiler through which the filament is ran. This apparently creates a polymer coating on the inside of the hot end, creating a slick surface with no drawbacks.

    Here is a link to one such thread: http://community.robo3d.com/index.p...hotend-jam-clogs-seasoning-and-an-oiler.3564/
     
  6. Thorinair

    Thorinair Member

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    Here is how my prints look like when there are no skips. This was printed at 210 °C. It may skip like, once during this whole print. It is very rare, but enough to ruin prints. First image is the top layer, then the bottom and finally side. I would say that that is quite a nice print.

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  7. Ephemeris

    Ephemeris Well-Known Member

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    Switch to a different roll of filament for a while. There are rolls with bad sections that nothing will help with. If you are sure you're extruding the right amount and that layer one is not too tight, you might want to manually verify your temperature is reasonable.

    With the hotend well above the work surface, disengage the idler, and try to manually feed the filament. Verify at what indicated temperature it seems to flow freely. Once that's done, reengage the idler and feed filament using the printer interface. If you can successfully feed a meter or two then I'd say the problem is not the hotend/extruder. Assuming that test was successful, change your temperatures in your slicer to match what you just determined, and do a test print. If it jams again, I'll still suspect over-extrusion, but let's cross that bridge when you get there.
     
  8. Thorinair

    Thorinair Member

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    I've already manually fed it multiple times and had no issues. I explained the temperatures I tried and what worked and what didn't in the original post. At 210 °C, I get a complete mess on a print like this because it is simply too warm, not from retraction, but because it just melts all over when tip of the hot end goes back and forth: https://www.thingiverse.com/thing:2080224
     
  9. Thorinair

    Thorinair Member

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    For example, this same retraction test at 200 °C is the most beautiful print that ever came out of my printer.

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  10. Thorinair

    Thorinair Member

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    If it helps anything, I have taken a closeup shot looking down into the hot end from the top with the PTFE tube removed.

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  11. Rob Heinzonly

    Rob Heinzonly Well-Known Member

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    Decrease the current of the motor and see what happens, looks like the motor is overheating.
     
  12. Thorinair

    Thorinair Member

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    Happy to say that I fixed all of my issues by oiling the filament exactly like most of the internet is raving about. Been printing for two days now with absolutely no skipping at all ever since I added the oiler.

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    Everything has been working perfectly, and I was even able to increase my speed a lot. And even while printing faster, I have never been getting prints as beautiful as I do now.

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  13. Spoon Unit

    Spoon Unit Well-Known Member

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    Oiling with what?
     
  14. Thorinair

    Thorinair Member

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    I have explained it previously in the thread. I use sunflower oil for frying, which has a high smoking point so it doesn't burn in the nozzle.
     
    Spoon Unit likes this.

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