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Odd 'latticing' in a print

Discussion in 'Troubleshooting' started by kick4h4, Jul 15, 2017.

  1. kick4h4

    kick4h4 New Member

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    Hi,

    I'm experiencing a print failure mode I don't recall seeing with my old printer. I'd rather not gather an extensive objective pile of evidence as to how repeatable this odd behaviour is, so I thought I'd run this by the collective and see if anyone can spot my obvious user error.

    I wanted to try a somewhat larger print that I had been doing, and decided to give this a try:
    https://www.thingiverse.com/thing:1023303
    This is titled the "Spiral Twister Storage Box". It looks like it is a decent test of a 'larger' print.

    I'm using Inland PLA, orange, purchased from MicroCenter at the same time as my printer. I have done a few smaller prints with this filament, and did not have any issues. I did have to dial in the slic3r print settings and raise the temp a little to avoid over-extrusion and slight partial nozzle blocks, but I think I've got that in hand at this point.

    I'm printing at just about 200C, and not running very quick, only 40mm/sec print speed. I don't think I'm straining the printer in any way.

    The box lid, 25mm, printed just fine, and the surface quality is very nice. Much better than I was usually getting with my Flashforge Creator Pro.

    However, when I ran the box body, this happened.
    20170715_124830-scaled.jpg

    Sorry for the stupid offset ruler, the bad behaviour started at just about 55mm from the bottom of the print.

    I don't recall reading much in the literature about intermittent latticing like this.

    I suppose it could be temperature related, but I've printed a couple of my standard test garden gnomes, which are 78mm tall, and they printed fine. They are basically tapered hat by 55mm, so they are not the same sort of figure.

    Do you fine folks have any suggestions as to what might cause this, and possible resolution? I'm willing to accept user error as a possibility...

    Thanks in advance for any advice.

    Cheers,

    John

    p.s.: Here's my standard garden gnome. I used this to test new spools of filament.
    https://www.thingiverse.com/thing:90171
    The photo in the object listing is hideous, the gnome looks pretty good. I have a nicely painted instance named "Gerald" who is my traveling gnome, and who goes with me everywhere.
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    That looks like some microclogging got you.
    PLA will do that. Seasoning the hotend is the best approach.
    If it is not that I am not really sure, it certainly was still extruding, but just not enough so I would tend to think it is a clog. Not a complete one.
     
  3. kick4h4

    kick4h4 New Member

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    For what it's worth, I always start my printer with a 'load filament', and let any platic in the hot end just spool out. After about 3 minutes or so, I hit the next button and get a clear ribbon of filament. If that ribbon doesn't look like it's .4mm, I'll repeat.

    My curiousity about microclogging is that the print is rock solid up until it isn't.

    I'll try to do a cold pull with the robo pla spool that came with the printer, and do a seasoning on it.

    Thanks.
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    PLA "just does this" when used with a brass nozzle :)
    It is slightly better with a steel one, but still subject to it.
    It is all about the way PLA is as a material.

    I just added a oiler to all of my machines and usually leave it on for all filament types.
    Stopped the whole problem. Well, until I forget to add more oil :)
    It takes a long time (weeks) for the oil to need to be 'refreshed' and I just forget sometimes.
    It is only a few drops added at a time so easy to forget.

    Not immediately fatal since the seasoning (just like a cast iron skillet) stays on for a good while.
     
  5. kick4h4

    kick4h4 New Member

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    I seem to recall seeing a discussion about that here. I wasn't sure where one would mount the oiler on a C2, though. Not a lot of places to clip things to.
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It is a challenge on the C2, but not quite a bit a one as our delta printer which has a 5 foot bowden :)
    You need to mount it before the bowden feed essentially.
    Before or after the filament run-out sensor... those are the easy spots.

    You can just season it though (without the oiler) and see if you can complete that print.
    A good seasoning will get you through half a dozen reasonably sized prints (on average).
    I am just too lazy to want to worry about redoing it.

    The thread you are looking for is here: http://community.robo3d.com/index.p...hotend-jam-clogs-seasoning-and-an-oiler.3564/
     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Bear in mind that the oiler does not end up (if done correctly) putting a LOT of oil into the mix. A correctly done oiler will put a very FINE sheen on the filament as it exits the oiler. Not a lot of oil at all. Just enough to maintain the seasoning.
     
  8. Kilrah

    Kilrah Well-Known Member

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    Never had such an issue with PLA.
    What I've had though is heat creep that softened the PLA at the extruder motor level and causing an improper amount to be pushed out, and it would look quite a bit like that.
    Seems pretty much impossible with the C2/R2 head design where the motor is so far from the nozzle though. Might still be worth checking the extruder fan is running properly.
     
    #8 Kilrah, Jul 16, 2017
    Last edited: Jul 16, 2017
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  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The C2 at least does not really have the motor very far from the nozzle on the primary extruder (the second one if you add it -- yes).
    So heat creep is a very real possibility, but only if your extruder cooling fans are not working correctly. They are easy to hear/feel so you can check those. I do not mean the fans that blow air on the bed to cool the print, but the ones that pull air across the hotend itself.
     
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  10. Kilrah

    Kilrah Well-Known Member

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    Well depends on your references I guess - I believe the R2/C2 use the same head, and the motor is 16cm away from nozzle / 6cm away from the first part that's supposed to be warm... On the printer I had an issue with (once, and becasue the fan wasn't running AND it was a low flow part) it's only 5cm/2cm!
     
  11. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The R1 had it at least double the distance, but it was not a direct extruder (geared -- GregsWade) and as I may have mentioned our delta has direct extruder and a 5 ft gap between motor and hotend :) Still a NEMA-17 just slightly more torque.
     
  12. Kilrah

    Kilrah Well-Known Member

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    Actually I was wrong, I did have such an issue once on my R2 - was reminded because it happened again just now.

    It's actually with terrible filament, I've got a copper spool that just melts at an insanely low temp, it already gets soft at around 40°C. The other day I printed a casing that failed so all I had was the ~3mm thick cover, and when I removed it it was surprisingly flexible... let it cool where it became better but still visibly soft, and just putting it back on the still warm bed (45°C or so) for a couple of minutes I could bend it 180° again.

    I'm now "wasting" it to print a couple of ornamental things because while it looks good it's obviously unusable for anything functional (the case was supposed to be for an electronic board that heats up quite a bit - turns out it would just have melted on me so once I noticed I switched material to reprint it).

    It was a bit surprising to have 4 hours or so of printing come perfectly clean and then stop extrusion. I think I understand why though - it's not heat creep from the extruder, it's actually the extruder stepper getting warm, which gets the shaft warm, which gets the filament warm and you're done if you've got one of those super soft materials.

    I'll now try removing the extruder cover next time I use this thing, hopefully it's enough airflow to keep things cool. Or I try to find a fan laying around.

    Note I've printed

    20170717_000654.jpg 20170717_000636.jpg
     
    #12 Kilrah, Jul 16, 2017
    Last edited: Jul 16, 2017
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Hah, heat creep from the stepper... that is a new one :)
     
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  14. Kilrah

    Kilrah Well-Known Member

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    All steppers seem to be run at quite a high current and get significantly warm after a while, maybe 40-50°. On my previous printer they never went much above ambient.
    Well they weren't encased either, so that probably plays somewhat of a role too.
     
  15. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Believe it or not the real key to that heat is the drive current. Our delta is the worst it needs a lot of drive current and those puppys run hot. Hot enough I added heat sinks. On a RAMPS board you could tweak the stepper drive current down and reduce heat, even a RAMBO will let you do that (but in the firmware). I suspect the Smoothie is like that as well. Regardless I see no adjustments on the C2/R2 boards... you could heat sink them if you think they are getting too hot.
     
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  16. kick4h4

    kick4h4 New Member

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    Thanks for all the input, folks. I just made a moai glasses holder as a gift for one of my siblings. 125mm tall, rock solid print all the way.
    (gold inland filament that had been stored in a Lowe's bucket for a year with a dessicant pack).

    I like the C2. :)

    Cheers,

    John
     
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  17. OutsourcedGuru

    OutsourcedGuru Active Member

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    I've actually printed a part from that original box. Mine turned out fine but I'll note how very thin the walls were on this design. You can see through the part walls at all edges.
     

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