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Unresolved "Mid-air" prints

Discussion in 'Troubleshooting' started by LarryM, May 30, 2016.

  1. LarryM

    LarryM New Member

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    Printing has been working fine for months. Suddenly today on the second print, after auto-leveling, the head moved to about an inch above the bed and started printing. I canceled, restarted the machine and now the bottom layer is not "solid" as before. I started another print after that and the same "mid-air" printing occurred. 2 subsequent prints have rather poor bottom layers. No changes have been made to any settings. Any idea on how to resolve this mystery? Details: MatterControl 1.5, Robo 3D R1 Plus, medium quality, PLA
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Sounds like one or both of your Z axis home switches is out of position and mistriggering.
    I assume you did not reset your Z offset (normally 1mm or less).
     
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  3. LarryM

    LarryM New Member

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    Thanks for the quick reply. I did not reset anything. Z offset is currently 0 in the print area section. Is the "Z axis home switch out of position" something I can fix?
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yes, look at them (they are on the crossbar attached to the threaded rods) and raise/lower the Z and watch them. You can see when they get activated (the crossbar will lift up as the extruder is driven into the bed until one of the switches triggers).

    You want them to both be correctly positioned and triggereing at nearly the same position.
     
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  5. danzca6

    danzca6 Well-Known Member

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    Those Z switch mounts get loose and tightening them up and making sure they are pushed down over the nuts on both sides of the axis is a common issue.

    Another thing I have seen burn me before is when it is auto leveling it lifts the x a bit on one of the probe points like normal, but it would stick on one side of the x axis and would throw off the remaining probe points. The x axis has the motor on one side that actually makes for an imbalance of the axis. Also with the R1+ and leadscrew upgrade Robo introduced these new z switch connectors that have these vertical wings that for me it would rub enough to cause it to stick. It can be frustrating for sure.

    These are machines and need some TLC every once and awhile. Be patient and you will be a master soon enough.
     
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  6. LarryM

    LarryM New Member

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    The switch on the right has considerable rotational "play" it in. Anyone have instructions on tightening it? Auto-leveling seems fine still, but first layer printing is getting considerably worse. Also, I noticed that brass nut on the left is barely exposed while on the right, almost the entire nut is visible. Is this is what is meant by "pushed down overs the nuts"? (I can send pictures if that would help)
     
  7. LarryM

    LarryM New Member

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    Pictures for comment above

    left side left.JPG

    right side right.JPG
     
  8. danzca6

    danzca6 Well-Known Member

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    right side is wrong, too high on the nut. Loosen up the endstop bracket (screw and nut in back) and push it down onto the brass nut. It should be very similar to the left side. Retighten and then adjust the X to be as close to level as possible. Just turn the screws left or right by hand to get it to go up and down until you are close as you can. Use a ruler or a dial gauge. Closer to level the better. The ABL routine will take care of the rest.
     
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  9. LarryM

    LarryM New Member

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    Thanks for confirming. The screw for the left z axis faces into the machine (easy access) while for the right it faced the side of the machine. (wrong part installed?) This meant taking the housing off the machine to perform the "reseating". What a pain.
     
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Both nuts are on the same sides because the bracket is a standard part (and they only have one style).
    Yep a pain if you actually use the covers.
     
  11. danzca6

    danzca6 Well-Known Member

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    The old style adapter I think you could flip and have the screw head on the inside for both. The new adapter style "now with wings" makes that impossible.
     
  12. LarryM

    LarryM New Member

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    Thanks for all the replies. I have the z switch situation resolved but now I have a jam/clog. (wonder if a messed up z caused this next issue) I was able to unload the filament but can't reload. The gear starts to strip the filament 1 3/8" from the end. After about a dozen attempts, I am fearing a more drastic course of action is needed. For my R1 Plus, where should I begin? I've read numerous threads here and on other sites but hoping my brief description gives a clue where the problem lies and the best resolution. TIA.
     
  13. Geof

    Geof Volunteer Moderator
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    Hi Larry, my suggestion is to remove the nozzle and use a butane torch to melt out the filament. Then season the nozzle when reassembled.

    You must do this hot together the nozzle off so please be careful... It hurts :)
     
  14. LarryM

    LarryM New Member

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    After a complete dismantle, I found a piece of filament broke off inside the top of the extruder. Now back to solve the printing. The raft prints fine but the consistency of the part is very sporadic as if not enough filament is being extruded. When I loaded the filament after clearing the jam, it "oozed" out the bottom as I turned the gear as expected. Now after a few canceled prints, nothing is coming out. Does this sound like a Z distance issue? Time to dismantle again. :(

    Here are the first few layers before I stopped it. Previously I would get nice smooth, flat bottoms to my parts.

    bad layer.jpg
     
  15. danzca6

    danzca6 Well-Known Member

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    Taking things apart and puttering it back together could change the z offset needed. That could be what you are seeing. Also make sure everything is properly tightened and secured with the hotend its mounting. Don't want any wobble.
     
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  16. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    PLA? Probably microclogs. Season the hotend or add an oiler. There is a sticky thread on this.

    Sent from my Xtreme Play Tab v2 using Tapatalk
     
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  17. Geof

    Geof Volunteer Moderator
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    It may be a partial jam. Is the hotend fan running? (the small loud one on the extruder)
     
    #17 Geof, Jun 3, 2016
    Last edited by a moderator: Jun 4, 2016

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