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X offset print failure after long prints

Discussion in 'Troubleshooting' started by sterling baldwin, Jun 13, 2017.

  1. sterling baldwin

    sterling baldwin New Member

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    For my longer prints (20+ hours), so far I'm 3 for 3 with failed prints. See pictures below. In all the cases it appears as though the printer misses a tooth or something on the x axis belt, giving it an unwanted x offset. I created a previous thread the first time this happened http://community.robo3d.com/index.p...hat-could-have-caused-this.18667/#post-109844, but the issue hasn't gone away. Any suggestions? I think the tension in the x axis belt is slightly lower then the y axis which might be the issue?

    Note that I did pause the print several times to switch the filament, but in each case it started up again with no apparent problems, it was only after it had been running all day that it had its error.
     

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    #1 sterling baldwin, Jun 13, 2017
  2. Geof

    Geof Volunteer Moderator
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    Hi there,
    You will want to check the belt tightness (it should twang if you pluck it, not thud) and also check the set screws in the timing pulley on the stepper( its a good idea to check them all and a better idea to add some loctite to them )
     
    #2 Geof, Jun 14, 2017
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Adjusting the belts is a real challenge on the C2 (and R2 I imagine). However you can check the belts. They should be quite tight --

    http://docs.robo3d.com/en/latest/

    Says nothing about belt tension adjustment :(
     
    #3 mark tomlinson, Jun 14, 2017
    Last edited: Jun 14, 2017
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  4. sterling baldwin

    sterling baldwin New Member

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    #4 sterling baldwin, Jun 14, 2017
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    There are alternative belt blocks that @Geof sent me pictures of -- similar to the Robo, but adjustable tension. I guess worst case you could perhaps swap to one of those if the need arose. I see no easy way to re-tension belts in the C2/R2
     
    #5 mark tomlinson, Jun 14, 2017
  6. Geof

    Geof Volunteer Moderator
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    What size are the R2 blocks, belts and rods? I can likely measure and find a different OEM with adjustable if needed. Of course someone could always measure...cad...and print and post for the group too :D (someone with a R2)
     
    #6 Geof, Jun 14, 2017
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I can measure the C2 ones, I assume there is no difference in that part.

    Rough numbers: 42mm x 38mm x 15.6mm (WxHxD)
     
    #7 mark tomlinson, Jun 14, 2017
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  8. Geof

    Geof Volunteer Moderator
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    Oddball sizes. I'd look into UM style blocks. May gain a few mm of build volume :D
     
    #8 Geof, Jun 14, 2017
  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I agree those are not straightforward sizes... not square even.
     
    #9 mark tomlinson, Jun 14, 2017
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  10. jwmueller

    jwmueller Active Member

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    When you get a chance, can you watch each of your main X and Y axis rods at high speed? For example on the touchscreen set the movement to 100 or 200 and watch what your rods are doing.

    If you have a bent rod I wonder if the extruder is catching on your print, skipping either the belt or the stepper and then it stays off from that point. The reason I ask is your prints are showing the same ringing texture that I had, see the vertical marks in all your prints? That pattern is way too regular, so it reminds me of either thin walls where the infill pattern is showing through or a sine wave pattern from a bent rod if that makes sense. How I caught this on my machine was by running the gantry at a higher speed and watching the end gantry plates that attach to the main axis rods. Low speeds I could not see it, high speed you can see a wobble in the rod and the gantry.

    Can you upload an STL?
     
    #10 jwmueller, Jun 15, 2017

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