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  • Off the build plate

    Hello All
    I have an issue with one of my printers. It was printing great. I needed to move it for a short time so moved it to another work bench got it powered up and when i went to run a print it now printing off the front of the build plate. I'm not sure what would have changed in that short time.
    Thanks Marc

  • #2
    Hi Marc
    There are lots of things that may affect machine functionality. In your case - maybe - the belt has been loosen, the homing was not right, the stepper is undercurrent. Can you show us in a sort video what are you experience?
    Thinking simple is the hardest way.....

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    • #3
      With mechanical endstops you always can get slightly different positions on every print. While for X and Y this is not an issue, even the slightest change on Z can decide between printing success or fail. I prefer my printers set up a little to close to the bed. This way the minor tolerances in Z will not affect the reliability of the printers. The first layer always is nailed down and never gets loose.

      Also make sure you endstops are mounted properly. The printer is frequently bumping into them and even if there is a leaver catching a real impact, there is always force applied to the switch itself and those tiny M2 screws usually used are not a real match for any kind of force.

      I also noticed that non CoreXY printers (The ones with a shaking bed) can easily decalibrated, when during transport or just setting it down a little to harsh, one spindle of the bridge part (z axis) turns while the other donĀ“t. Result is a print bed to close on one side and to far away from the nozzle on the other. This of course depends on how the printers are build. These Z Rod timing belt solutions are no use for normal printing, but help a ton, when moving your printer around.
      Last edited by Geit; 08-20-2020, 05:14 AM.

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      • #4
        Often, when one of my printers suddenly fails, I find a cable that came loose. Check the cables on all of your end stops and stepper motors. Check that the wires in the cable connectors are going all of the ways into the connectors.

        A good skill to learn for diagnosing 3d printer issues is how to use a USB connected terminal emulator. There are many alternatives and I have used a number of these in my videos about GCODE, but probably the easiest to set up is MatterControl from MatterHackers. Completely free and works with most printers. Don't worry about selecting the exact 3d printer you have since if you are only using it for the terminal features this will not matter much.

        Then try issuing some standard G Code commands. For example: G28 --- which will home the printer. You can learn a bit more about gcode in this video:

        https://youtu.be/cJlre1lEdcQ

        The following video demonstrates a Chrome APP that you can use as a USB 3d printer terminal:

        https://youtu.be/lR5QjnohsRk

        Both of the above videos have examples of how to use gcode.

        Once you understand how to connect to your printer and issue gcode command you can use these to diagnose issues.

        Hope this helps. Irv

        P.S. Make use you use a high-quality USB cable. The low-end cables sometimes only have the power pins connected and not the data pins.

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        • #5
          Thanks for the tips. I did have a video but it was to big for here so I will try again.

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          • #6
            I don't think you can upload videos to this forum at all; only photos.

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            • #7
              Well, if you print off the plate, then this sound that it doesen't homing correctly. I trust mechanical endstops than optic or magnetic. The reason that chacks twice the endstop position, is beacuse it measures the steps from the returning off the first hit fo the endstop and back. If the endstop luck of signal in 20 steps - this is just an example - and powers up in 23 or 25 step ( 5 steps more ) then the controller will accept it because there in no encoder to feed back the loosing steps. More than 5 steps, then will show up a Homing error. Somewere in the firmware, you can configure the homing steps tolerances as well. If this sound too much, then you can just check the endstops manually as well as the belt tightness and the pulleys fasteness too. Mostly this problem has to do with mechanical lucks than software's.
              Hope this helps.

              P.s. upload video in Dropbox and post here the link for us to download it/them.
              Thinking simple is the hardest way.....

              Comment


              • #8
                I'm not sure if this could be the issue or not. When I home the printer this is what I see. Shouldn't they all be at 0?

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                • Vassili Finellis
                  Vassili Finellis commented
                  Editing a comment
                  Z -0.19 means that it looses 0.19 mm ( 190 microns ) off. Afterall this is negligible.

              • #9
                I don't have your printer but that looks like the z-offset distance. As long the first layer sticks!

                Cheers
                Last edited by Alan; 08-25-2020, 09:56 AM. Reason: Typo

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                • MarcSchuh
                  MarcSchuh commented
                  Editing a comment
                  The bed is leave very well. Just printing the wrong place and I rally don't know who to get the back to 0.

              • #10
                Originally posted by MarcSchuh View Post
                I'm not sure if this could be the issue or not. When I home the printer this is what I see. Shouldn't they all be at 0?
                I don't believe the Z distance would have anything to do with printing outside of the bounds of the print bed. Z is the height, not the width or length. So, even if it was 0, I doubt it would make a difference. As Alan says, as long as the 1st layer is adhering to the bed nicely, then the Z value is OK.

                Now, as to your problem, when the printer is homed, where is the hotend? Is it in a place that makes sense?

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                • MarcSchuh
                  MarcSchuh commented
                  Editing a comment
                  That is what got me so confused. It at the lower left and right were it should be.

              • #11
                I think you need to test movement of the hotend. Connect a computer to the printer using USB. I don't know how large your print bed is, but use a metric ruler to mark off several distances on a piece of graph paper: 100,100; 100,10; 10,100; 150,150; etc. Fasten the graph paper to the print bed, putting the 0,0 point right where the hotend is located when it's homed. Then, run Pronterface. Tell Pronterface to connect to the printer. Once connected, tell the hotend to move various distances by issuing commands like G1 X100 Y100. See where the hotend winds up. Take notes.

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                • MarcSchuh
                  MarcSchuh commented
                  Editing a comment
                  Thanks,I will give that a try

              • #12
                Stupid question. How did you slice the model? You need to tell the slicer how big the bed is and the offset from 0/0 till the bed starts.

                So, could it be that you simply used a wrong printer profile to slice the part? If the printer has a bigger print volume than yours, it will start to print outside, as the printer itself is stupid and has no max endstops. Since a slicer will place the part into the center, it is possible that this centered position is not on your build plate.
                Last edited by Geit; 08-25-2020, 05:33 AM.

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                • Vassili Finellis
                  Vassili Finellis commented
                  Editing a comment
                  Not stupid question, but the best question !!!!!!!!!!!!

              • #13
                Excellent point Geit. So my idea of verifying the positioning of the hotend, combined with yours to make sure the correct printer profile is being used, should confirm whether the printer is working or defective.

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                • #14
                  Yes was using the right profile. I have been printing great until I moved the printer to a new bench. But yes something to look at but it looks good to me.

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                  • #15
                    Originally posted by MarcSchuh View Post
                    Hello All
                    I have an issue with one of my printers. It was printing great. I needed to move it for a short time so moved it to another work bench got it powered up and when i went to run a print it now printing off the front of the build plate. I'm not sure what would have changed in that short time.
                    Thanks Marc
                    I know this sounds weird but check to see if there is a cable or something that is hitting the limit switch between the bed and the switch itself. Sounds like the limit switch is being triggered before it should be making the printer think the bed is all the way back before it truly is. The fact that you moved it further supports that it might be more likely to be a physical problem then a software setting. Or maybe the switch got bent? Just a thought.
                    Last edited by Larry; 09-08-2020, 02:30 PM.

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