7.5 hours into a print and filament stops flowing (notch)

Discussion in 'BigBox General Chat' started by AndyVirus, Sep 5, 2016.

  1. AndyVirus

    AndyVirus Well-Known Member

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    Hello,

    I know this is a bit of a "how long is a piece of string" question but here goes anyway:

    What would be the likely causes for extrusion to stop nearly 8 hours into a print? When i checked the filament had the loverly notch eaten out of it so i can only assume that it could not be pushed out of the nozel anymore so decided to feast on the filament. This is on a Titan Direct.

    I have had this before on shorter prints due to over extrusion but never after such a long period of time.

    It was E3D Everyday Black ABS 1.75mm. I am using a 0.4mm hardened steel nozzle with v6 hot ends.

    Fan was 0% so i would not expect rapid cooling preventing flow. I doubt over extrusion unless so minor it took 7-8 hours to build up.

    Any ideas?
     
  2. Kanedias

    Kanedias Well-Known Member

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    Are you printing at a high speed that the abs doesn't have a chance to melt quickly enough? Does it keep happening at the same time into any print or just once? If it's just once could be dirt, if it keeps happening then maybe more likely heat creep, cheek your extruder assembly and reapply thermal paste perhaps.
     
  3. Tom De Bie

    Tom De Bie Well-Known Member

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    If it happens after 8 hour I think it's probably because of a knot/twist on the filament reel.
    That makes it unpossible to untwine the reel of filament and then the extruder grinds away the filament until it has no more grip
     
  4. AndyVirus

    AndyVirus Well-Known Member

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    Printing was at 50mm per second. Will try slowing it down. Unfortunatly that was my longest print to date. Not made it past 4 hours before either just due to what i was printing or still calibrating/changing materials etc. So i have nothing to compare it to yet. If it was dirt (from another filament previously used) would i not have seen issues many hours before? The print was perfect up until that point (perfect i know is subjective). Ill try more and see if it occurs again then maybe look at heat creep. Thanks!
     
  5. AndyVirus

    AndyVirus Well-Known Member

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    Ill take a look at the reel. It seemed to be moving but it was late so swore at it and went to bed :). That was my first thought too, will have a propper look when home.
     
  6. AndyVirus

    AndyVirus Well-Known Member

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    Ok so im home... Looks like the nozel/hot end is pretty heavily clogged... No idea why but should do soon i hope...
     
  7. mike01hu

    mike01hu Well-Known Member

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    Do look at your retraction settings, if used, which should be less than 2mm. If higher then retraction can draw the melt into the heat-break where it can stick and cause a jam; even after a long print time environmental changes can influence the heat-break's effectiveness. Dropping the nozzle temperature a bit can help.
     
  8. AndyVirus

    AndyVirus Well-Known Member

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    I originally was using 1.5mm retraction which was default in the S3D profile for bigbox dual hybrid. I reduced it to 1.1mm a while back and all has been good (till now). I did see somewhere that E3D uses .6mm retraction distance for Everyday ABS so may give that a go. Heres some pics of the clogged mess... IMG_0540.JPG IMG_0539.JPG Acetone soak coming right up
     
  9. mike01hu

    mike01hu Well-Known Member

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    It does look like melt is heading back to the heat-break. How well does the PTFE tube fit, as there must be no free movement to allow a gap to appear at the heat-break?
     
  10. AndyVirus

    AndyVirus Well-Known Member

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    I thought it fitted pretty good but i have re-done it now and ensured it was in firm with the clip pulled up so it should not move. When i push the heat sink back into the carridge; will that push the clip back down allowing the ptfe tube to move again? Or should there be enough clearance by design? I assume there was some play as thinking about it i did hear clicking on retraction before, need to try again to see if it has gone away or it is just the natural noise if the titan on retraction.
     
  11. mike01hu

    mike01hu Well-Known Member

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    Without going back to the build instructions on assembling the Titan-direct, the tube cut to an exact length (83mm?) to ensure a tight fit. Others who cut the tube too short had jam problems; the manual is a bit confusing on this point. The clip should remain up if you insert the hotend carefully.
     
  12. AndyVirus

    AndyVirus Well-Known Member

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    I am pretty sure that i did cut it to the correct length described in the manual but i will check again ensuring it is 83mm exactly just incase. I have some spare PTFE tubing as i was planning a swappable dual head for volcano's once i am very confident (not to be confused with competent :) ) with standard blocks/nozzles, so if it is off i can at least cut a new piece. Thanks!
     
  13. mike01hu

    mike01hu Well-Known Member

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    Do make sure it is the tube with the smaller inside diameter.
     
  14. AndyVirus

    AndyVirus Well-Known Member

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    What? I did not realise there was different ID! Well i used the bit that came with the extruder kit so hopefully thats the correct ID. Will check now i know!

    Also the build guide is damn confusing on the length required as the "Hybrid" section says 63 for single and 66 for dual but then later after searching for "83mm" its further down in the "Titan" section... Right, now to strip it all out and check the length as i cant remember what i cut at build time... Good news is i have 2 spare v6 kits (planning volcano hot swap at some point) so should have 2 more lengths of the PTFE with the correct ID. What should the ID be for this? 2mm?

    Edit: OK, The tube was 82.1mm, now i have a pair of digital callipers i have cut an exact length of 83mm. This shows that i at least found the Titan section when i first built it, but on my spare i had cut a 66mm so promptly forgot about that :) ID is 2mm OD is 4mm
     
    #14 AndyVirus, Sep 11, 2016
    Last edited: Sep 11, 2016
  15. GeckoBox3D

    GeckoBox3D Well-Known Member

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    Filament being chewed is caused by alot of factors...

    -- Obstructed filament feed, eg, tangle, or friction in the system somewhere along the filament path.
    -- Motor too strong. Ideally, if your extruder can't push any more filament it should skip steps rather than chew filament. This is partially to do with hobbed bolt design as well. I've found the titans hobbed gear is a little chewier than a MK8.
    -- Too many retractions. Not an issue if you ask me. Tighter idler tend to stop this better than looser idlers on the extruder in my opinion. others may find differently, and again has a lot to do with hobbed bolt design.
    -- Retraction too long, I've not experienced this before on an E3D hotend unless I remove the filament manually and it forms a plug. mess around with retraction settings, or get a V6 lite.
    -- Hot end jamming. This is a discussion in its own right. But a weaker motor is good here, as a temporary obstruction means that you get skipped steps rather than chewed filament. I'd rather have some underextrusion for a layer and see a print finish, than waste 8 hours of print time / material.
    -- Hotend temp too low/too hot. Higher than necessary temps can cause heat creep (unlikely though), too low of a heat will cause underextrusion and possible jams. If the heat is too low, this will show up on the prints. they might be more brittle / poor layer adhesion.

    I might have missed something, but keep all these in mind and keep checking on your printer. Most of these issues should be noticeable even on short prints if you care to look for the symptoms (eg, flakes of 'chewed' filament around the extruder)

    *EDITED, added points to list*
     
    #15 GeckoBox3D, Sep 11, 2016
    Last edited: Sep 11, 2016
    mike01hu likes this.

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