SOLVED Filament starts to get stuck and grind

Discussion in 'Calibration, Help, and Troubleshooting' started by Duncan Chivers, Nov 2, 2016.

  1. Duncan Chivers

    Duncan Chivers Well-Known Member

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    Strange problem since I swapped back to a partially used reel of filament - it seems to get stuck and start to grind, and then obviously stops feeding through. I'll post a couple of videos later to illustrate; I've tried different amounts of pressure on the extruder but it doesn't help.
    This filament was fine about a month ago and I've kept it in a bag with a silica pouch, but all I can think is that it has somehow become softer. But if that's the case why doesn't it do it all the time?
    If I extrude 30mm manually, it starts to fail about half way through.
    Help!
     
  2. Henry feldman

    Henry feldman Well-Known Member

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    Not to be silly, but you checked for a overlapping loop? This happened to me the other day with a ProtoPasta spool, where it was tangled over itself and had this exact behavior (although the Titan won and snapped the filament eventually).
     
  3. Duncan Chivers

    Duncan Chivers Well-Known Member

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    That's a very good point, I haven't checked that. I'll have a look when I get back, thanks.
     
  4. Henry feldman

    Henry feldman Well-Known Member

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    Took me 3 failed prints before I figured out (when the filament snapped in the PTFE tube).
     
  5. PsyVision

    PsyVision Moderator
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    I hate that, take the filament out of the PTFE and bam it coils back and overlaps itself. I can't reach the back of my machine very well so keep doing this :(
     
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  6. mike01hu

    mike01hu Well-Known Member

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    I always lift the reel off before pulling the filament out, then clip it before it decides it can wrap itself better than I can. :eek:
     
  7. Truman123

    Truman123 Active Member

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    I am having the same problem of it getting started fine then starting to grind away at the filament. I thought it may be the retraction doing it so i turned it off. turns out that wasn't the problem. any other ideas?
     
  8. mike01hu

    mike01hu Well-Known Member

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    Are you saying that grinding happens when you start a print? If so, your initial layer height is too small, possibly due o poor levelling.

    Retraction only happens on non-extrusion moves and, along with good temperature setting and control, helps prevent ooze and stringing. As you will read in this and other threads, retraction must be below 2mm to avoid hot filament from being drawn back across the heat break where it can stick and cause jams; this is a particular issue with PLA.

    To better help you need to provide more information about your setup, such as printer version, bed information, firmware version, nozzle size, filament used and temperatures. Pictures are a great help.
     
  9. Truman123

    Truman123 Active Member

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    The filament usually starts failing about halfway through. I have a big box dual hybrid, Bed at 50c, firmware is what came default with it, nozzle is the nozzle supplied with it, filament is the test that came with the printer(PLA i think), printing at 215c.
     
  10. Duncan Chivers

    Duncan Chivers Well-Known Member

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    I've found that increasing the nozzle temperature stops the grinding, but now I'm getting a completely different issue, which I've attached a picture of. I can't seem to catch a break!
     

    Attached Files:

  11. mike01hu

    mike01hu Well-Known Member

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    There seems to be a couple of problems here. I'll start with the bed and your preparation; if that is glue stick on the bed, then there is far too much as only the lightest of smear is required, preferably only in the area to be covered by the print job. My preference on glass was to use PVA juice, a 5:1 mix of water to PVA wood glue, lightly brushed onto a very clean bed, cleaned with alcohol. Next, your first layer seems to be thick and not being laid so that there is not good contact between individual tracks and the tracks and perimeter, so I would suggest checking the first layer height, extrusion width and perimeter overlap; to do this I print a single layer part and adjust the parameters as necessary and save them for this filament type, colour and maker for future reference and most slicers allow you to save various profiles. You do not say if you have cooling on or not, as for PLA it should be turned off for the first few layers. All of this assumes that your initial nozzle height is correct through the levelling process and that you are printing with a sensible speed; too high can cause similar issues for single small parts.
     
  12. Duncan Chivers

    Duncan Chivers Well-Known Member

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    Thanks, yes it's glue, I will clean it up and use less of it, I guess I have been lazy (slap wrist!). I'll also check the first layer height. I've already increased the overlap by 20%, and yes I've made sure that there's no cooling initially.
    I'm not sure where to go for extrusion width in S3D, unless you are referring to nozzle size?
     
  13. mike01hu

    mike01hu Well-Known Member

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    These are the typical settings I used for one job. The extrusion width is set to "Auto" so that S3D makes a guess as to how much filament to extrude based on layer height and the extrusion multiplier; the latter you can tweak to adjust the feed rate that is normally fixed by your extrusion steps setting in the firmware. I have in the past, for trickier filaments, switched from Auto to Manual and set a value for extrusion width but having been happy with my current setup the Auto setting seems to work fine now.

    2017-01-15 (1).png
     
  14. Duncan Chivers

    Duncan Chivers Well-Known Member

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    That's really useful, I'll have a look later and see how mine compare.
     
  15. Duncan Chivers

    Duncan Chivers Well-Known Member

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    Ok, so I think I may have found the problem (or at the very least another one!).

    I've realised during the course of trying to check the nozzle (for completeness), that the temperature doesn't seem to be calculating correctly - as soon as I turn on the device it reads as around 100 degrees at the nozzle. It's currently reading 133, but I can happily touch it without burning myself, it's room temperature. So I guess that it's probably not heating to anything like what I ask it to, but I have no way to be sure.

    I have the Titan upgrade and there's a PT100 amplifier wired up next to my Rumba, so I'm assuming that it needs the PT100 sensor, and would need a v6 heater block for sensor cartridges if I replaced that too?
     
  16. mike01hu

    mike01hu Well-Known Member

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    You certainly need the PT100.
     
  17. Duncan Chivers

    Duncan Chivers Well-Known Member

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    So it was definitely the temperature sensor. Removing it and ensuring that it has sufficient slack once it was put back (on the advice of Greg) solved the problem straight away. Further than that the prints are now coming out really well!
     

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