Suddenly started dropping tools, getting worse !

Discussion in 'Getting Started' started by Yakeru, Apr 9, 2020.

  1. Yakeru

    Yakeru Member

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    Hello,

    So i was using my TC rather intensively these past few weeks, and it was working very well.
    I was mostly using a single extruder.

    Then I started a print using two extruders, and everything started going downhill...
    I never managed to finish my print, despite several tries, I wasn't looking at the printer so I didn't now why it failed each time. But sometimes the printhead shifted by 5 cm or so, sometimes a tool dangling from it's cable...

    Then when watching the whole print, I saw that It sometimes was dragging the tool out of its holder after unlock, and droped it, so I cleaned and lubed everything and it worked well again for 2h and started dropping tools again.

    After tinkering for a while, I ended up starting from scratch : I re did the commissioning, installed RRF 2.0.5.1, got the last files from e3D on github to start from a "clean" SD card and a recent firmware. No change. When alternating between T0 and T1, occasionally, it would miss and either drop the tool or completely mess up it's positioning by hitting the post when trying to park a badly held tool ...

    So, trying to understand what the printer was doing, I ran the lines from tpre0 one by one, looked fine ... then tried again after modifying tpre0.g to reduce the speed significantly (from 50000 to 10000 for starter), and it got worse, after that change in tpre0, after a Home all, (which behave a bit strangely as well) If I ask to grab T0 , it moves vaguely up to the centre of the build plate, slowly, jerkyly, and tryes to grab air :/ I never managed to grad a tool since then.

    No idea what's happening, don't know where to start to troubleshoot...

    Please help ! :)

    PS : By home all that behaves trangely I mean : home Y looks ok, but while homing X, Y moves around to, which I never noticed before, then at the end when parking the head at the front, it often hits, looks like Y is messed up. Once the home all is done, if I push the head by hand, it moves diagonaly : the back left motor resists, but not the back right.
    Could it be that something with the hardware/current/driver went bad ?

    PS2 : Yep, after issuing a command like G1 X100 Y100, it moves. But once stopped, I can again push the head by hand diagonaly, easily, back left motor resists, but not the back right. They should both be energized equally right ?

    PS3 : Using another controller for motor B (the one not resisting) didn't help. Could it be that I burnt a motor ? !!

    PS4 : HAAA found the issue ! Gear on motor B's shaft just got loose :D
     
    #1 Yakeru, Apr 9, 2020
    Last edited: Apr 9, 2020
  2. Nibbels

    Nibbels Well-Known Member

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    Hello, I had kind of the same experience.

    I lost steps when attracting the tool.
    Thatwhy I boost the amps to 600mA only when changing. See:
    https://forum.e3d-online.com/threads/from-rrf2-to-rrf3-on-duet2-wifi.3500/page-2#post-35781

    Additionally I got the stall detection up and running some time ago. But every time after some days or weeks I had to increase the current for doing this. Lately it was quite stable then but yesterday I recognized that my "fallback" = "homing without stall detection after stall detection failing" did happen.

    That means that something changes over time. Yes, I use lubrication... And I even lubricated the gears of the motor after things got worse.

    Before that I got great results by perfectly adjusting the dock position for each tool. If you are off in X-Y-Z when attaching the tool it gets harder to attract it. The docking position should be perfect!
     
  3. Yakeru

    Yakeru Member

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    Hey I didn't see your answer ! So I continued editing my first post :)

    I found the issue, the gear on motor B got loose !! (only one grub screw, no thread lock apparently)

    After fixing that, I got back to the state where everything was moving normally again, but occasionnally dropping a tool.

    So like you said, I am testing various values for Y in tpre0, and changed from 242 to 243, for now it seems to be working fine.

    Will continue testing :)

    Thanks !
     
    Nibbels likes this.
  4. Yakeru

    Yakeru Member

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    Now I must admit that it is a bit worrisome that things move a bit over time, to the point where it gets from working perfectly for days to, dropping tools all over the place 1 hour later ! I am tempted to write a little macro that runs a dozen tool changes, at reduced speed, so that I can have a look before starting a long print to check that everything looks and sounds right :)
     
  5. Spoon Unit

    Spoon Unit Well-Known Member

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    I just posted something about my challenges with tool collection to the end of this thread. Maybe there's something useful in there. Bottom line, you'll probably do better when you redo all your collection gcodes and manually tweak them to perfection.
     
  6. Yakeru

    Yakeru Member

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    Yep, that's what I am doing right now !

    I had to increase max Y by one mm for tool 1. I'm using a value slightly above 243mm.
    What I am doing basically is going back and forth on Y until I hear a little "clik" when the grabber advances in the tool, so until it touches something, then I remove 0.1 mm and use that as the position to grab the tool. So I go as far as possible without touching anything.
    I also increased the current to the servo to 600 mA just while it locks as Nibbels suggested.
    Now I an waiting for my silicon/ptfe grease to arrive because I can hear a little bit of squeaking when the servo locks the tool 1.

    Now it seems to be functioning well again, did a print in PLA with PETG support, so it was changing tool at each layer for 3h and no issues. Back to 100% reliable again it seems.

    But I'm surprised by the change I had to make to the tool 1 Y positioning, almost 1 mm, and suddenly, out of nowhere ... I will keep an eye on that !
     
  7. Spoon Unit

    Spoon Unit Well-Known Member

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    I think a little click is OK. You just don't want a CLUNK. So I keep that 0.1mm that creates the click. I see my coupler current is at 500. Hadn't looked at it for a while. I think this is because I gave up trying to configure stalling, and just happily let the lower current fail to drive it when it reaches the max. Then I know I'm homed.

    It's possible the 'out of nowhere' was simply down to a change in usage. Either not homing before the print, or switching between tools in a different order. Or switching tools at all.
     

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