Extruder clicking/going backwards



  • So, i have runned into an issue on my corexy build and i dont have a clue on what might be the problem.

    When i try manually tell the printer to extruder, no problem at all, but when printing the extruder clicks, and i have figured the pattern that it clicks.

    For example, imagine a flat square, when its doing the solid infill as soon as it reaches the edge line of the square and goes backwards the extruder clicks, if its a small section and has to do that really fast a lot of times the extruder clicks so much that its going backwards.

    I have tried with filament and tried motor without pushing filament. I even tried a different motor with same results. I have changed the current on the motor from 0.8 to 0.5 and still the same.

    I manage to print part of a print before, but it always clicked somehow, but now its even worst.

    Im using the Duet 2 Maestro with the latest 2.03 build.



  • @pedromelim said in Extruder clicking/going backwards:

    I have changed the current on the motor from 0.8 to 0.5 and still the same.

    Please post your config.g, the specification of your hot end thermistor, and the make/model your extruder motor, extruder and hot end. This may help to track down the problem.

    Regarding motor current, you probably want to increase the current on the extruder motor, not decrease it, but this will depend on the motor, though 500mA is low. I'd expect the clicking noise is the motor skipping, as it doesn't have enough torque to push the filament. You can usually see this by watching the filament feed into the extruder; it will bounce back rather than feed in as the motor clicks. When extruding into air (with space below the nozzle), there is a lot less force on the extruder compared to when it is printing, as the nozzle is effectively blocked by the bed (for the first layer) or the previous layer. So your extruder motor, and the extruder's grip on the filament, needs to be strong enough to overcome this. And it gets worse as speed increases.

    One simple test is to increase the hot end temperature. If you have not set your hot end thermistor correctly, the temperature may be over-reading, so you may not be hitting a high enough temperature to extrude consistently.

    However, there may be a multitude of other problems that cause an increase in extrusion pressure: incorrectly assembled hot end causing heat to creep up the feed tube, friction in Bowden tube, weak extruder and/or motor, partially blocked hot end, etc etc. It really could be anything!

    Ian



  • @droftarts said in Extruder clicking/going backwards:

    @pedromelim said in Extruder clicking/going backwards:

    I have changed the current on the motor from 0.8 to 0.5 and still the same.

    Please post your config.g, the specification of your hot end thermistor, and the make/model your extruder motor, extruder and hot end. This may help to track down the problem.

    Regarding motor current, you probably want to increase the current on the extruder motor, not decrease it, but this will depend on the motor, though 500mA is low. I'd expect the clicking noise is the motor skipping, as it doesn't have enough torque to push the filament. You can usually see this by watching the filament feed into the extruder; it will bounce back rather than feed in as the motor clicks. When extruding into air (with space below the nozzle), there is a lot less force on the extruder compared to when it is printing, as the nozzle is effectively blocked by the bed (for the first layer) or the previous layer. So your extruder motor, and the extruder's grip on the filament, needs to be strong enough to overcome this. And it gets worse as speed increases.

    One simple test is to increase the hot end temperature. If you have not set your hot end thermistor correctly, the temperature may be over-reading, so you may not be hitting a high enough temperature to extrude consistently.

    However, there may be a multitude of other problems that cause an increase in extrusion pressure: incorrectly assembled hot end causing heat to creep up the feed tube, friction in Bowden tube, weak extruder and/or motor, partially blocked hot end, etc etc. It really could be anything!

    Ian

    I have tracked it down. I disabled Pressure advance and the clicking stopped instantly. I even tried enabling it afterwards mid print and the clicking started again.

    Probably my values for speeds accelerations and jerk are probably interfering with pressure advance?

    I will leave the values here to see if anyone can get some insight, as i wanna take advantage of the pressure advance.

    ; Drives
    M569 P0 S0 ; physical drive 0 goes forwards
    M569 P1 S0 ; physical drive 1 goes forwards
    M569 P2 S0 ; physical drive 2 goes forwards
    M569 P3 S0 ; physical drive 3 goes forwards
    M584 X0 Y1 Z2 E3 ; set drive mapping
    M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation
    M92 X80.00 Y80.00 Z400.00 E409.31 ; set steps per mm
    M566 X900.00 Y900.00 Z60.00 E3000.00 ; set maximum instantaneous speed changes (mm/min)
    M203 X15000.00 Y15000.00 Z300.00 E8000.00; set maximum speeds (mm/min)
    M204 P6000 T6000 ; Set printing and travel accelerations
    M201 X6000.00 Y6000.00 Z60.00 E3000.00 ; set accelerations (mm/s^2)
    M906 X800 Y800 Z800 E500 I30 ; set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout



  • The values for the extruder look ok. What pressure advance value were you trying to use?



  • @Phaedrux said in Extruder clicking/going backwards:

    The values for the extruder look ok. What pressure advance value were you trying to use?

    Tried S0.1 and S0.2 and both gave the same problem.



  • Those are fairly high values. How did you arrive that them?

    Is this a bowden or direct drive setup?

    What is the max rated current of the extruder motor? 500ma is fairly low.



  • The behaviour you observe with the extruder is normal when using PA. The clicking sound you hear is most likely backlash if it's a geared extruder or possibly an extruder bearing issue. My E3D Titans used to do it, my Bondtech BMGs do not.



  • @Phaedrux said in Extruder clicking/going backwards:

    Those are fairly high values. How did you arrive that them?

    Is this a bowden or direct drive setup?

    What is the max rated current of the extruder motor? 500ma is fairly low.

    Its a bowden setup. Im not sure about the current, asked already about the datasheet to the vendor.

    @deckingman said in Extruder clicking/going backwards:

    The behaviour you observe with the extruder is normal when using PA. The clicking sound you hear is most likely backlash if it's a geared extruder or possibly an extruder bearing issue. My E3D Titans used to do it, my Bondtech BMGs do not.

    Its a BMG clone.

    The thing is, i tried the motor without being in the extruder, just to see if without load of pushing the filament would act the same, and it does the same thing.



  • turn off pressure advance. and check again.



  • @pedromelim said in Extruder clicking/going backwards:

    The thing is, i tried the motor without being in the extruder, just to see if without load of pushing the filament would act the same, and it does the same thing.

    It will. It's normal behaviour with PA. The important thing is how does it print? Have you actually got a problem with print quality or is it just that the extruder is doing what looks like strange things but print quality is otherwise fine. ?



  • @Veti said in Extruder clicking/going backwards:

    turn off pressure advance. and check again.

    Thats what i tested after first post, works fine without pressure advance.
    What i think its too weird and not at all normal to be happening, its that even if the motor is not on the extruder, even sitting on the desk by itself it does that.

    @deckingman said in Extruder clicking/going backwards:

    @pedromelim said in Extruder clicking/going backwards:

    The thing is, i tried the motor without being in the extruder, just to see if without load of pushing the filament would act the same, and it does the same thing.

    It will. It's normal behaviour with PA. The important thing is how does it print? Have you actually got a problem with print quality or is it just that the extruder is doing what looks like strange things but print quality is otherwise fine. ?

    With PA Enabled? Severe under extrusion. Without it, corners are looking horrible. Thats why i turned it on and tried to tune the rinter. Im gonna try tunning it better without PA, but eventually would want to turn it on again.

    I used S0.1 and S0.2 because it was what was advised on the wiki as a standart for bowden tubes of about 400mm.

    Also im gonna try get my speed, acceleration values and jerk values tuned as what i used was based from someone else.



  • @pedromelim There is an interaction between extruder instantaneous speed change (jerk) and PA. You need to set extruder "jerk" really high - it won't have any adverse effects if you set it too high. I use 3600.

    But yes, you should tune speeds, accelerations and carriage "jerk" first. Then also determine the best temperature to print at. Only then should you introduce PA. Note also that with PA enabled, you will likely need less retraction. Also, anything which affects the viscosity of the filament (e.g. temperature) will have an effect on the amount of PA required.

    Just ignore what the extruder does - it's print quality that counts.

    HTH.



  • @deckingman Tks, will try adjusting my Speed, Acceleration and speed change.

    Probably the retraction is causing the problem even more, as in the beggining when i turned PA on it wasnt that bad, but once i started changing values in the slicer in the day after, it went really worst.

    When i get to PA again i will try changing the retraction settings and see what i can get from it.



  • @pedromelim The "problem" is that the extruder clicks when going in reverse (as per your title) yes? It manifests itself during retraction or with PA enabled. In both those cases, the extruder can run in reverse. So stopping the extruder from doing those types of moves, or limiting the amount of reverse movement won't cure the problem. It'll merely help to hide it. As I said before, it's likely backlash in the gears or possibly a faulty bearing. It might be worth checking that the grub screws holding the hobbed gear on the motor shaft is tight. If it was a genuine BMG then I'm sure that Bondtech would advise, supply replacement parts, or even replace the entire unit if it was under warranty. You could try approaching the supply of the clone to see if they would offer the same service.



  • @deckingman said in Extruder clicking/going backwards:

    @pedromelim The "problem" is that the extruder clicks when going in reverse (as per your title) yes? It manifests itself during retraction or with PA enabled. In both those cases, the extruder can run in reverse. So stopping the extruder from doing those types of moves, or limiting the amount of reverse movement won't cure the problem. It'll merely help to hide it. As I said before, it's likely backlash in the gears or possibly a faulty bearing. It might be worth checking that the grub screws holding the hobbed gear on the motor shaft is tight. If it was a genuine BMG then I'm sure that Bondtech would advise, supply replacement parts, or even replace the entire unit if it was under warranty. You could try approaching the supply of the clone to see if they would offer the same service.

    As said before...the noise and the clicking still happen when the motor is not attached to the extruder. Thats why it doesnt make sense how much it is happening.



  • can you try adding
    M569 P3 D2
    and see if it still clicks.



  • I think I encountered and tried to explain the same problem a while ago. TL;DR: Duet CPU can max out given enough steps per mm, speed, acceleration and print resolution.

    I suppose that stepper control is no longer fluid, probably due to too many interrupts? The only way to solve it is to reduce print speed, disable PA, move to direct extrusion, reduce print resolution (or get another board, ha, except there aren't any really better ones other than Duet 3).

    You might try slowing your printer down and it might help enough so that it prints. Lower the speed, increase the X, Y, Z jerk, perhaps.



  • @pedromelim said in Extruder clicking/going backwards:

    As said before...the noise and the clicking still happen when the motor is not attached to the extruder. Thats why it doesnt make sense how much it is happening.

    I must have missed that. So it's the motor that makes a clicking noise, not the extruder yes?



  • @Veti said in Extruder clicking/going backwards:

    can you try adding
    M569 P3 D2
    and see if it still clicks.

    Tried it and its the same, but seems less prominent.

    @deckingman said in Extruder clicking/going backwards:

    @pedromelim said in Extruder clicking/going backwards:

    As said before...the noise and the clicking still happen when the motor is not attached to the extruder. Thats why it doesnt make sense how much it is happening.

    I must have missed that. So it's the motor that makes a clicking noise, not the extruder yes?

    Ya, well...the "clicking sound" only happens when attached to the extruder but the motor on its own does the same movement.

    Probably all of this is just bad config speeds jerk etc. My experience with pressure advance was only on a Prusa Mk2.5 and i had none of these issues.



  • @pedromelim said in Extruder clicking/going backwards:

    only happens when attached to the extruder but the motor on its own does the same movement.

    as deckingman said. the backwards movement is exactly how Pressure advance works.

    check the grub screws inside of the bmg. they can become loose as well.


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