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Print trail shifts whilst printing

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  • michalko99michalko99 Posts: 153Member, 🌟 Super Member 🌟
    Hi. Yes you answered, but there was no real result as nobody seen behavior and clear result. Maybe trying Pronterface method would be leading to some conclusion
  • MattMatt Posts: 314🌟 Super Member 🌟
    Ok. Though I guess that neither a footage could have been able to match what is the real behavior.
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    Could an eventually worn belt be also a culprit? I remember that I substituted already a stepper, which was the one of the z axis. Andm, substituting bearings looks very difficult (no tutes around).
    Post edited by Matt on
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    I try to connect with com3 @ 115200, but it says that it can't due to invalid baudrate.
    My observation is still this: if it is just a matter of mechanics, why the issue appears regularly around the same moment? and, I stiffened the belt, and it appears later: I losened the belt and it appears earlier.
    Post edited by Matt on
  • michalko99michalko99 Posts: 153Member, 🌟 Super Member 🌟
    edited March 2021
    I looked in Marlin configuration and COM speed shall be 250000. I am not using serial port for A5, so I just put value which I set on my other printer..

    Do not think much what it could be. Just try how it behaves and post results. Best would be to see video. Share it on Youtube, you can delete it later. And please do not make video which will be 3 seconds long. Nobody can focus on such a short footage :smile:

    Hmm..You never mentioned that you replaced stepper before...

    Thanked by 1Samuel Pinches
    Post edited by michalko99 on
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited March 2021
    Solving the problem requires systematic elimination. Possible causes:

    1. Motherboard stepper driver malfunction
    2. Loose Cables
    3. Stepper motor fault
    4. Bearings jam
    5. Pulley Slip on Motor
    6. Belt slip on pulley

    To verify 1, suggested to swap E and Y axis stepper drivers.
    To verify 2, have checked all cables inserted firmly.
    To verify 3, suggested to swap stepper motor between E and Y.
    To verify 4 I suggested to do slope bed test to measure angle, and also manually move bed by hand to feel for jams.
    To verify 5, need to check the grub screws on the motors.
    To verify 6, need to inspect the entire belt for worn/damaged regions.

    My guess is still a bearing jam. A long video recording of the printer showing the print process (including both good y action and defective y action) would be useful.

    If you do not perform systematic elimination the problem will take a long time to find --Β  it has been one month on this problem already.
    Post edited by Samuel Pinches on
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    1. Just in january I finally replaced one of the z steppers (the printer is 3 years old) which went broken some 9 months ago: I had to wait for the right stepper after many trials...): thereupon, I substituted also the drivers, but in installing them one of them burned out and ruined the original mainboard... So I had to order other drivers and another mainboard... Then it came to flashing the firmware, and I faced other issues, between weird firmwares sent from them and not so precise instruction to flash... Now it came to this problem with the bed.
    2. I'm unable to make this program work.
    1. drivers swapped: the malfuntion persists.
    2. Cables ok.
    3. Β This test was in my mind for today: I have other steppers spare, but I guess they wouldnt work, 'cause of wiring difference (alas: they could have worked as substituted...). Though, must I physically swap the stepper of just put the wire of the Y on the E? (which is hard: I have to unglue the Y...).
    4. I cannot fathom this fact: I cannot realize how much of a friction shold be to be correct. Anyway, the bed starts to move at 13Β° and runs down from the slope once inclined at 27Β°.
    5. Didn't checked it, but they look both good: I bought a wire camera, hope I'll be able to footage the inner behavior asap.
    6. The belt looks fine
    Still, a thing baffles me, I refrain: if it is just a mechanical problem (either stepper, belt cog/pulley, bearing), then why the issue begins to appear always around the same moments and place? Always when beginning to print the diagonal filling of the base layer. When I loosened the belt, it began since printing the perimeter of the cube. When I tightened her, it began later than usual, still when printing the filling, but it happened anyway.
    Thanked by 1Samuel Pinches
    Post edited by Matt on
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    Case opened, dismounted Y stepper. First: the belt looks somewhat mangled in some parts. Second: the belt extremity to the belt lensioner from the other side is wrapped just around a couple of bearings! I guess that it had had bneen better if wrapped around another cog like the one of the stepper (or not?). In case, which is the type/nome of the cog which I should buy?
    Test finished. The pop is diminished. Perhaps the real culprit is not the stepper, but the system cog+belt.
    Post edited by Matt on
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited March 2021
    Hi Matt, you could replace those bearings with a pulley idler, but I think the existing design is sufficient. The belt is fixed to the y carriage in the middle, so when it is tight, there is not much room for it to walk side to side.
    Next thing to do might be to replace the belt, and see if that improves the print quality. It sounds like that (#6 on my list) might be the culprit?
    It is hard to evaluate the damage without photos, feel free to upload some if you have time.
    Post edited by Samuel Pinches on
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    Hi friend. Well, we proceeded by exclusion, and we had to dismantle the whole printer to aknowledge it (the most boring part is to open it each time when trying a new operation...). Anyway, let's see: I'm about ordering 5mts of a 2gt 6mm belt (please look whether it is any good https://www.amazon.it/gp/product/B07BSK9Q52/ref=ox_sc_act_title_1?smid=A3BI8G9NTBZUKM&psc=1). On amazon so it arrives sooner. Perhaps a steel core had been better?
    As for the cog: please allow me to test this too: I need the specs for both the stepper cog (I'll substitute it too) and for the cog to substitute the current bearings on the tensioner pulley (the bearings may squeze/deform/slipper the belt's teeth, being not toothed).
    Whiltst I'm about buying, how must I search for the knobs of the leveling bed? One of them got a chipped thread and doesn't keep the screw line.
    Post edited by Matt on
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    Changed the belt, reduced the vref to 4.4 and 4.1, and the result embettered: but ths "clik" was still there and the print went not so good. So I changed it at 3,7, and the probblem became more evdent, as much as when the vref was at 5,5. It seems thus that the vref must be set around 4 or 4,1: but it seems anyway that it isn't the complete solution. Surely it isn't a matter of stepper, due I swapped the Y with the E.
    Post edited by Matt on
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited March 2021
    Great job Matt. I think that this is some good progress. In my mind now all signs are pointing to #4 as the culprit. If the bearing jams, the motor might stall and grind against the belt, wearing it out.
    Post edited by Samuel Pinches on
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    Well... But... Why it happens always while doing the same operation? How could the bearings be the culprit, if the tuning of the vref has been proven to affect the most of the slipping? The bearings are a mechanical part: if they might fail, the failire should appear at any times, not yet always during a precise phase of the printing.
    Btw, since 2 weeks I'm still in wait for the jg crew to gather from his "techs" the correct vref...Β Β 
    Post edited by Matt on
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited March 2021
    Ok. Vref for A4988 stepper driver is on the wiki. No need to wait for JG. Up to 0.7V max on y axis, but 0.6V should be fine. So I conclude: I think this is a mechanical problem.
    You did the slope test, and it stopped part way -- this is a mechanical issue. Your videos during printing have sounds when the y-axis moves: most likely a mechanical sound.
    I have said that I think this is the bearings multiple times in this thread,and I still think this is the case.
    Please try this:
    1. Β Ask someone else to record you, so the camera can be held still and steady, and so we can see the whole situation at once, in focus. Please record the following tests.
    2. Do the tilting test I suggested before, again. Please show the bed starting to move, and show where it stops part way. Then, slowly increase the angle until it starts to move again. Do not change the tilt angle while the bed is moving.
    3. Please place the printer on the table, flat. Please move the bed by hand slowly, over the full range. It should be smooth over the whole range. If it gets stuck somewhere, then the bearings are at fault and must be replaced.
    You can also disassemble the entire y axis further, and remove the bearings, and the smooth rods. If you slide the bearings on the rod back and forward (maybe with some twisting load with your hand) you should be able to tell if the bearings are smooth, or defective.

    Best,
    Sam

    Post edited by Samuel Pinches on
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    Another test: Try to print a small 20x20mm cube on the printer. Try to print it in several different spots on the bed, and see if the printing location, affects the print quality.
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    Hi Sam.
    • I know it's on the wiki: but I've guessed that they had had know it better than anybody else, also for testing their seriety and solicitation in real help (which looks to me rather kinda farce).
    • I bought an endoscopy cam, and I scoped what happened inside when printing. Nothing anomalous was seen: though the cog played smoothly, but the rumors of the click/pop came apparently from the side of the stepper (which cannot be the culprit though, due now it is the one which was on the extruder and viceversa).
    • I'll check the slope anyway again and hope the bearings will help, once they'll arrive.
    • Already did the spot test: nothing changes.
    • I'll try also to put in the smoothers again, with new bearings...
    See you. Best.
    Thanked by 1Samuel Pinches
    Post edited by Matt on
  • MattMatt Posts: 314🌟 Super Member 🌟
    I cannot find any gt2 pulleys for the Y stepper: what is the default one?
  • michalko99michalko99 Posts: 153Member, 🌟 Super Member 🌟
    ah Matt. Why are you still writing something what do you think, instead of printing what Sam asked for. There is no real help from your side while you are doing your own investigations without any evidence. Sorry, but in that long time that you are "solving" issue, somebody would build its own printer. Sorry, but I had to write it,...
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    • Already did the spot test: nothing changes.
    Post edited by Matt on
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited March 2021
    @Matt -- before or after changing the belt?
    Post edited by Samuel Pinches on
  • MattMatt Posts: 314🌟 Super Member 🌟
    Unfortunately, both.
  • MattMatt Posts: 314🌟 Super Member 🌟
    While I'm searching for spare parts, I would like to substitute also the toothed pulley: but I didn't found that kind of part in the wiki. What is its name?
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    @Matt I don't understand your question. Please take the part out and count the number of teeth on it. There is it's name?
  • MattMatt Posts: 314🌟 Super Member 🌟
    I meant the gear fitted to the stepper's shaft, which rotates the belt.
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    Yes, the motor pulley.
  • MattMatt Posts: 314🌟 Super Member 🌟
    Yes. How do I search for it? Pulley 20 teeth gt2?
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited March 2021
    Exactly. The only other thing you need to add is the internal hole diameter -- for nema 17 stepper motors that is usually 5mm bore. So search "GT2 20 5mm pulley" - just obviously avoid the idler ones with bearings as they are for the non-motor end.
    Post edited by Samuel Pinches on
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    Ty friend. I'll get the ones with grain screw, of course. Btw I anyway bought also the idlers (ones with bearings: I have intention to try a mod for substituting the simple bearings on the tensioner: I guess ther are 3mm bore). Apropos of bearings, hope that I'll have not to substitute even the bearings' shafts...
    Post edited by Matt on
  • Samuel PinchesSamuel Pinches Posts: 2,997Administrator
    edited March 2021
    You're welcome. I don't know about grain screw, you may call them grub screw or set screw.
    Post edited by Samuel Pinches on
  • MattMatt Posts: 314🌟 Super Member 🌟
    edited March 2021
    Yes, grub screws: I bought a batch of them and in the chinese page they was called "grain".
    Post edited by Matt on
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