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Slicer problem?

Discussion in 'Troubleshooting' started by Lance Weston, Oct 4, 2020.

  1. Lance Weston

    Lance Weston Active Member

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    I am printing a tube about 1" in diameter and 1/8" thick. As I adjust the Cura 4.71 parameters for finish and the part moves around on the printing plate I get a flat on the outside of the tube.

    I could use some insight.
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Pictures help, but I assume (sight unseen) that it may be the layer endpoints all lining up in a row. In Simplify3D I keep Random Start and Endpoints selected. This is not a panacea since if there is in fact a minor glitch in the way the layer start or endpoints are getting put down (like a small gap) then it will still happen, but because it is all scattered it will not give you a "seam" on the outside. It may give you small randomized blobs and zits... But that is a different problem to solve (via: https://www.simplify3d.com/support/print-quality-troubleshooting/blobs-and-zits/)

    Sadly I am not a Cura user so I can't give you pointers there.
     
  3. Lance Weston

    Lance Weston Active Member

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    In Cura I am using a random z seam. The outside diameter is 1.122" the flat is only on one side an measures 1.107 flat to other side. The .015 flat does not show in the photos but is visible when holding the piece. The flat is not on the model. Right now I am upping my cooling, possibly some shrinkage?

    More info:

    Took the same Gcode and put it on a different machine, an R2 with the Partsbuilt board. The flat was gone. The machine with the flat has a Partsbuilt board but is dual Z and a 12" bed. The problem must lie in the Marlin code or corrupted Marlin code.
     
    #3 Lance Weston, Oct 4, 2020
    Last edited: Oct 4, 2020
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It could be mechanical related I suppose, but GCOde could be at fault if you resliced for each machine.
     
  5. Lance Weston

    Lance Weston Active Member

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    I do not think mechanical because I rotated the part 90 degrees and the flat stayed on the same location on the part. I used the same GCODE and did not reslice.
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    So the flat did not rotate with the part or it did? If it did not I'd lean towards mechanical, but if it did rotate with the part ... Yea, that is not mechanical. I am not sure it is GCode either, but it is as likely that as anything else I can think of. Odd issue.
     
  7. Lance Weston

    Lance Weston Active Member

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    The flat rotated with the part. The exact same gcode on a different machine had no flat. The machines have different bed sizes and the large bed size runs dual z steppers. The flat occurs on the larger bed. They both use the partsbuilt boards and the robo raspberry Pi code. I am starting to favor a round off error when using a larger bed or corruption in the Marlin code .
     
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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  9. Lance Weston

    Lance Weston Active Member

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    Thanks for your help Mark. I am printing properly now. I did two things: I replaced the custom assembly that was on the 6mm shafts that after a year and a half felt "stiff" with a new Robo ball bearing assembly, and I went into the Octoprint Robo profile and made the profile reflect the size of the bed.

    I suspect your first instinct that it was mechanical was correct. On closer inspection all four "sides" of the round part had flats on them. But 3 of the 4 I really had to look for. I have no clue what the mechanical problem was or how it could give me the flats, but none the less it did. I can't imagine what changed after a year and a half.
     
  10. tkoco

    tkoco - -.- --- -.-. ---
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    The obvious answers 1) (software) Cura has changed over the time frame and 2) (mechanical) wear and tear.
     
  11. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The way a slicer does arcs is complicated. Since the printer can't "do" circles (unless it is a delta) the slicer has to math it out in small segments and it is not impossible for there to be a math error.

    That said if you have one or more sides that is/are printing correctly and only one that is not... I'd go with mechanical first.

    I'd start by suspecting a spot/section of the gantry that is not smoothly moving -- 'stickage' or more friction at least.
     
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  12. Lance Weston

    Lance Weston Active Member

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    I would not be Cura, since I am using the same GCODE on all machines. It could be Marlin, but the most obvious is mechanical. I did fix it but do not know why the mechanical fix worked. I use oversize steppers so that dragging on the bearings will not be a problem. I had zero slop in the print head. Everything was perfect, it just did not work right anymore.
     
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The R2 gantry is complicated enough that a section/corner of it being not perfectly squared up and positioned correctly can be a potential problem. My C2 arrived with one of the (top) rods completely out of the flange bearing and that took a good bit of time to get it back in place and then squared back up /aligned. If you do align it use the tools that Robo sent and if you do not have them -- print them.
     
  14. Lance Weston

    Lance Weston Active Member

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    That would apply if I had touched the alignment, which I did not. This is my 3030 aluminum extrusion "R2" and the gantry design does not require external tools. It has the alignment built into the design and can be set more accurately than the Robo R2. The only thing that changed was I swapped out the bottom piece of the print head. I had printed out a custom piece that used bronze bushings that had been running 24/7 for a year and a half. The fit on the 6mm rods had zero play and gave me higher quality prints than the Robo design. I just put on new Robo parts with the 6mm slide bearings. It was an easy swap out, I had a spare new bottom piece from Partsbuilt.com. The Partsbuilt bearings did "feel" better than the bearings I got from eBay and China, and the resulting fit on the 6mm rods was tighter.

    Does make me scratch my head. The steppers are 48mm, part numbers ending in 01, so they are faster and I have to give them 30% more current for greater torque. If I put my hand on the print head while it was printing it took considerable force to make it stutter.
     

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