More Extrusion Help Requested



  • I have read through a few good threads on extrusion issues, but I am not clear on a few things.

    DuetWifi 1.0. I get 100mm when I ask for it. Manual Bowden. Titan off by itself with it's motor.

    I'm using Simplify3d, and my first question is whether I should use M82 or M83 on this extruder. I presume it defaults to M82 (absolute).

    Everything I print comes out stringy, and if I leave the printer going, it will stop feeding filament. If I keep my hand on the large wheel on top of the extruder, the filament will feed, although it will eventually start to give me the odd click, and then more clicks.

    If I hold down the release lever and manually push the filament, I will get a good stream through the hot end. When I let go and let the extruder go by itself, it will stop giving me nice even lines, and then it will stop giving me anything.

    I don't think it is current for the motor, because if I keep pressure on the top gear, it feels very strong. It's like it backs up in the hot end until it can't push it through, and then strips the filament so it won't feed it.

    I have tried temperature from 190 to 225 (PLA) and it doesn't correct the behaviour. I have tried cranking the filament feed tension all the way in, and backing it off, and it won't keep going at either end.

    I think it must be the amount of filament I am giving it. In the web interface, Feed amount is 10mm and feedrate is 5mm/sec. My config M92 line is X80 Y80 Z400 E333.33 which is the number I used to get the 100mm to work.

    I know it's a wrong setting somewhere, but I am going around in circles.

    Thanks
    Tim


  • administrators

    With S3D I used M83 and relative extrusion, by checking "Relative extrusion distances" in the G-Code tab of the process settings.

    Regarding the extruder, if the motor clicks (skips steps) but the filament will feed OK if you give the motor a little help, then that is a sign that the motor isn't producing enough force. What is the rated current of the motor, and what E motor current have you set in the M906 settings in config.g? You may need to turn up the motor current.

    OTOH if the extruder strips the filament instead of skipping steps, that suggests either too little filament feed tension, or a blocked hot end, or too low a hot end temperature. When printing PLA, if the heatsink fan isn't running continuously and keeping the heatsink cool, this will cause the hot end to block.

    Stringy prints are a sign of insufficient or too slow retraction, or extrusion temperature too high.

    HTH David



  • Hi dc42

    Thanks for the information. My motor is good to 1.7 and it is at 1.1 right now. Should I bump it up to 1.4 or 1.5?

    I will adjust my setting in S3D regarding M83 and relative extrusion distances.

    My hot end fan is running reliably, and it is on whenever the machine is powered up.

    You have confirmed my belief of what the indications were showing. Thanks, Hopefully I can narrow it down from there.

    I think the retraction settings are pretty low at the moment. I will check that in out.

    Tim



  • I have notched up the current from 1.1 to 1.2 which is where all of my other motors already were. The M83 line in config.g has been uncommented, and "Relative extrustion distances" has been selected in the G-Code tab.

    I am getting far fewer clicks and only occassionally am I "helping" the extruder. I will likely bump up the current a tiny bit more.

    There is certainly a noticeable difference in what is being laid down.



  • I note that the extruder is a Titan but what is the hot end? It sounds a bit like you might be getting some heat creep issues causing the filament to swell and "bind" in the heat sink liner.



  • Hi:

    The hotend is E3dV6 and I have had it apart to make sure that the heat pipe and the nozzle would be against each other. I have also trimmed the end of the plastic tube so that it is square. I did have problems with both of those issues when I started off.

    I have bumped up the current a little more to 1.4 and it has made a big difference. I still have times when it will click, but not like it did before.

    This is an external bowden extruder and I had mounted the drive motor about level with the print head. What I discovered was that when the head came back to near home, I was getting more clicks. I moved the drive motor up the Z axis on the left side so that it would be a gentle arc in the feed tube from the extruder to the print head rather than a tight bend. It appears the bend was too tight and the filament was binding in the tube.

    The printer is now printing on it's own without my having to help it. I have the feed set at an amount of 5mm and a rate of 5 mm/sec. I do still get clicks and at times my filament will thin out and just leave little tiny blobs until the filament starts feeding properly again.

    I have the filament hanging on a small metal rod (which is the bar out of the top of my tripod) and it doesn't seem like it would resist the filament spool, but?…..

    Not sure what else could be holding things up unless it is clogging as you mentioned up front. My nozzle is at 210 and for the most part it is laying down a good consistent bead.



  • It sounds like there is some resistance to the filament feed because it seems that every time you increase the extruder motor current it improves things. That may just be the arrangement of the Bowden tube or a combination of various things. You said in one of your previous posts that the motor was good for 1.7 Amps. Is that the rated current? A good rule of thumb is to set the motor current to 85% of the rated current so 1.44Amps would be about right. As you have discovered, keeping the filament path as straight as possible will also help (as will keeping the Bowden tube as short as possible but without any sharp bends). Some people swear by Capricorn PTFE tubing. I haven't tried it myself but it's supposed to be low friction so it might help.

    My 5 colour Diamond hot end uses a modified version of E3D heat sinks and suffered from heat creep causing the filament to swell in the area of the heat break and "bind" inside the PTFE liner. The cure for that was to increase the air flow over the heat sinks so that's something that might be worth trying on your V6 ( a bigger fan).

    My 5 reels of filament all sit on horizontal rods similar to yours - albeit quit large diameter printed cylinders that fit over 2020 aluminium extrusion but they still rely on the extruder "dragging" it off the spool but it's not a problem.

    Another thing to watch out for is to use just enough but not too much retraction. It is possible to draw molten filament up beyond the heat break where it will solidify and cause a blockage.

    HTH

    PS. Having just re-read your OP, it sounds very much like the heat creep issue that the standard 5 colour Diamond hot end suffers from. So, I'd try a bigger fan on the heat sink. Oh, and is it a genuine E3D V6 or a clone? If it's a clone, that may well be the cause of all your problems.


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