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Unresolved Excessive Bed Flex On Left Side

Discussion in 'Troubleshooting' started by cybershipley, Jul 14, 2016.

  1. cybershipley

    cybershipley Member

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    I have 2 Robo3d R1+ printers at work. One of them works just fine, but for the other one... I have never been able to get the bed leveling correct, and have resulted in just using a dial indicator to level the bed.

    I finally had some time today to look more closely at the problem, and the only thing I notice is that the bed flexes a great deal on the left hand side when performing the G29 auto level. As a result, I think this causes that side to scrape the bed because the software thinks it sits lower than it really does.

    Could this be the reason the bed leveling is off? If so, is there any fix for this or something below the glass to look for. I looked and didn't notice anything, but I didn't know what to look for. I did a G28 and then the M119 see if the switches were being depressed, and they are. I know the bed is pretty level to begin with, the switches are in the correct orientation, and I use a dial indicator before every few prints.

    If there is no fix, can someone recommend an easy replacement (not another Robo3d bed as the last one I had shipped was cracked upon arrival) such as a piece of aluminum (how thick) and a new heater that's compatible (I know it's 12v), but what would you guys recommend? At a loss here. I really hate having to use the dial indicator all the time and adjust the offset for this machine.

    Thanks in advance, you guys are awesome.
     
  2. Geof

    Geof Volunteer Moderator
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    Have you done a paper leveling to level the x to the bed ?
     
  3. cybershipley

    cybershipley Member

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    Yes, that's what I do with the dial indicator.
     
  4. Geof

    Geof Volunteer Moderator
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    So if that side is still high you can shim under the magnet on the other side to manually level it so auto level works :)
     
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  5. cybershipley

    cybershipley Member

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    I can level it manually, but leveling using G28...Z offset...G29 doesn't work. The left side really bows down when the nozzle pushes down on that side (doesn't happen on the other printer). I have shimmed the back because the y axis was off.
     
  6. Geof

    Geof Volunteer Moderator
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    I'm talking about physically leveling the bed. Not the x axis. Double check your magnets are all there.
     
  7. cybershipley

    cybershipley Member

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    I have physically leveled the y axis. I'll do the same with the x tomorrow. The magnets are there. I don't know why it bows so much on that side.
     
  8. Ryan TeGantvoort

    Ryan TeGantvoort Active Member

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    I had a similar issue and after removing the Y-Axis smooth rods to install new rods, one of the stock rods (left side when looking at the front) was terribly bent causing high numbers front and back and a low number in the middle. This only occurred on one side because the opposite rod was still straight.

    After installing the new straight smooth rods and bearings, I have been getting much better numbers for auto-level.

    Something to check I guess?
     
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  9. Geof

    Geof Volunteer Moderator
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    I'm very interested in seeing this. Could you share a photo? Does it bow if you just push on that side?
     
  10. cybershipley

    cybershipley Member

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    I'll post a video tomorrow, as it's at work.
     
  11. Geof

    Geof Volunteer Moderator
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    Thank you very much! Intrigued to see whats happening.
     
  12. Rigmarol

    Rigmarol Well-Known Member

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    Eagerly following this one. I'm having a similar issue. No matter what I do (I've read all the suggestions) the left side of the bed is higher than auto level thinks it is. I'm going to look close to see if mine bowing during auto level too.

    I've been just pausing the print and turning the left z screw (rod?) and resuming and repeating until it's what I want then the rest of the print job is fine.
     
  13. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Once Marlin 1.1.0 is released the new MESH leveling scheme will be a good solution to flexible beds as it does not use the probes for anything but homing.
     
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  14. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Bed flex can be caused by anything loose -- magnets not seated well, rod holders/bearing housings loose (they can work their way loose). So start by lifting the bed and making sure everything is seated nice and tight.
     
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  15. cybershipley

    cybershipley Member

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    I tried to take a video, but it really doesn't show what's happening clear enough. The left front bows alot, while the back right doesn't hardly bow at all. After I finish this print, I'll take another look under the bed.
     
  16. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Pay attention to the bearing blocks the rods run through and make sure they are firmly in place.
    Look for anything cracked too...
     
  17. cybershipley

    cybershipley Member

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    Everything looked ok under the bed as far as I could tell. I just can't understand why the glass is being pushed down so far in the front left corner. I really think this is causing that corner to print so close to the bed when auto leveling. I guess I'm gonna have to get a heater/piece of aluminum to see if that fixes it. In the meantime, I'll just level using the dial indicator. Hmmmm. Suggestions where I could get a piece of aluminum, what size, thickness, and a heater core to go with it? I have HVAC tape and cork for a heater already. Guess I'll look at it one more time at work on Monday.
     
  18. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If it moves down something is 'giving' and allowing the moment :)
    The rails if firmly mounted are not going to just flex.
    Lift the bed and try to push down on the rails in that corner and see what is moving
     
  19. cybershipley

    cybershipley Member

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    I have decided to replace the 8mm rods and bearings for the y axis (left side). I think this may be the root cause (a bent rod or bad bearing). What's the easiest way to get this done? I did print out extra pillow blocks, tensioners, and ends incase I need them.

    Thanks in advance.
     
  20. Geof

    Geof Volunteer Moderator
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    Its a bit of a chore but power off and remove power cord. take off the y belt and ribbon cable clamp. Take the glass off and set someplace it wont be broken. Remove the bottom cover, mind the small fan with way to short of wires. You will see nuts on the bearing blocks. Remove all the nuts and take off the bed assembly. Replace what parts you need and reassemble
     
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