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Extruder Skipping

These skips will typically be wider than 📄pockmarks.



Skipping below top layer:

  • If you are printing PLA, don't do it in an enclosure. Enclosure temps can easily get hot enough to soften PLA in the extruder/heatbreak and cause endless jams. Open your chamber door - or better yet, take the panels/enclosure off entirely.

  • Mark a line on your extruder motor shaft with a sharpie (on the back side of the motor). Observe what it's doing while the issue is occuring.

    • Shuddering: A wiring issue or mechanical resistance.
    • Not moving at all: A wiring or electrical issue, or stepper driver overheating.
    • Rotating normally: Either the filament isn't gripping properly, or a grub screw has come loose.

  • Try a new nozzle. It's often just a partial nozzle clog.

  • If it occurs mainly on the first layer, ensure that you are not printing with 📄too much squish or with too much first layer flow.

  • Ensure that your filament gear tension (usually a spring tensioner screw) is not too tight or too loose.

    • Yank on the filament and keep tightening the tensioner screw until it stops slipping. Tighten it a little extra, maybe 1-2 turns. Too tight will cause skipping, and too loose will cause filament stripping.

  • Use a reverse bowden tube* with direct drive, and ensure that there is not too much resistance coming from the spool.

    • *Reverse bowden tubes go from the direct drive extruder back to the spool (and should be fixed at the spool side), and prevent fast toolhead movements from yanking the filament.

      • Use a 3mm inner diameter tube. 1.9mm/2mm ID tubes are more restrictive.
      • Ensure that it doesn't have any kinks.
      • Ensure that your spool is not catching on anything as it rotates.
      • If you are pulling from a dry box, try without.
      • For Voron spool holders, make sure you have the PTFE tube piece installed to lessen friction.
      • If your bowden tube is FEP or another material, try real PTFE instead.

  • For Voron direct drive toolheads, ensure that you have the short piece of PTFE tubing installed between the clockwork and the hotend.

    • Make sure it is not too long or too short. You should trim it down until it just fits without compressing the tube.

  • Ensure that there are no issues with your hotend fan.

    • Ensure that your hotend fan is running and is not stopping/starting during printing from a wiring issue.

    • Also ensure that your hotend fan is running at 100%.

      • Some vendor githubs have the [heater_fan hotend_fan]'s max_power setting at 0.4 (40%) for some reason.
      • Ensure that you are running it at the correct voltage.

  • Ensure that your hotend thermistor is correct in your config and that you are not using temps that are too low.

  • ⚠️ If you use any NTC 100K B3950 thermistors, update Klipper to the most recent version and change all instances of sensor_type: NTC 100K beta 3950 to sensor_type: Generic 3950 in your config. There was a 📄bug causing these thermistors to be inaccurate, which was fixed with a 📄recent deprecation.

    • Please note that some other features have been deprecated recently too. If you have not updated Klipper in a while, please see 📄here for instructions on how to fix up your config for the new Klipper version.

      • You may also need to recompile/reflash your MCUs if you get a "command format mismatch" error after updating. See 📄here.

  • Ensure that your retraction distance is not too high.

    • The default Cura profile uses a high retraction distance, as it is configured for bowden.
    • You should generally use a maximum of 1mm for direct drive.

  • With the filament latch open, try extruding by hand. It should be easy.
    If there is much resistance, figure out where it is coming from:

    • You may need to drill out the filament path in the printed parts.
    • Your nozzle may be partially clogged.
      • See if extruded plastic is shooting out to the side instead of straight down when extruding in mid-air.
      • Unclog it using a cold pull or nozzle cleaning needles.
      • Try a new nozzle.
    • Your heatbreak may be partially clogged.
      • Remove the nozzle, cool the hotend, and try pushing fresh filament through it. Make sure to cut off the bulged tip. If there is resistance:
        • Unload the filament and remove the nozzle.
        • Get access to the top of the hotend (you may need to either remove the hotend or the clockwork).
        • Shine a light through the hotend and look into the other side. See if there is any plastic stuck against the walls of the heatbreak or heatsink. If it is obstructed:
          • Unplug the hotend fan.
          • Heat the hotend up to your normal printing temp for that filament.
          • We are purposefully inducing heat creep to soften the plastic in the heatbreak.
          • Push a long, thin (<=1.8mm) allen key or similar through the top side of the hotend to push the obstruction out of the bottom.
          • ⚠️ Turn off the hotend as soon as you have freed the obstruction.
            • If you let it cook without cooling for a long time, it will eventually start to soften the printed hotend mounting.
          • Be careful - don't burn yourself!

  • Ensure that you are using the correct run_current for your motor. Too high or too low can both cause skipping.

    • As a general rule, don't exceed 50-60% of the rated current of your motor as your run_current. Some motors like more or less current, though, so your best bet would be to look at the stock configs or to ask in Discord.

    • Clockwork 2 / Galileo / Orbiter:

      • There is some confusion about different motor models.

        • If you have the 20mm 1a LDO motor, try ~0.65a.
        • If you have the 17mm 1a LDO motor, try 0.35-0.4a.

  • Check your extruder motor and hotend fan's 📄crimps and wiring.

  • Check the volumetric speed preview in your slicer. See if it is 📄high for your particular hotend. Or see 📄here to determine your maximum.

    • If you are exceeding hotend limits, try lowering your volumetric speed limit in your slicer (PS/SS) or reducing line widths / layer heights / speed (other slicers) until you are under the limit.

  • Try rotating the extruder (if possible) without filament loaded. It should be easy.

  • Try using a cooling mod, like the 📄AB-BN. It optimizes hotend cooling and can help with heat creep issues.

  • Try lowering your extruder motor's microstepping and disabling interpolation (and stealthchop if you have it on, which you shouldn't).

  • Take out the motor, and see how powerful it feels. See if you can stop it easily with your fingers. This may indicate a bad motor or bad wiring.

BMG Clockwork

  • Try turning the plastic gear with your finger with the motor turned off and filament unloaded. It should be relatively easy. If there is too much resistance:
    • Ensure that you have a small amount of 📄backlash in the plastic gear.
      • If they are pushed together too hard, it will cause resistance.
    • Ensure that your drive shaft is not rubbing against the motor:
      • A little cheat I have heard here is to test continuity between the drive shaft and the motor. Test throughout the full rotation.

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