Calibrated Esteps Causes Extruder Skipping

  • I have replaced the stock extruder on my Ender 3 with one of these:

    New Extruder

    The grip gear has a smaller diameter, so I calibrated the esteps as per the top google search: Extruder Calibration – 6 Easy Steps to Calibrate Your Extruder...

    If I set the esteps so that it's spot on with 100 mm of filament is used up when I ask it to extrude 100 mm, then during a print I get the occasional skip on the extruder.

    If I dial it back a bit and set it so that it extrudes 90 mm of filament when I ask it to extrude 100 mm, then I don't get the skips.

    In both cases the print looks normal.

    I've tried changing the nozzle as well in case there was some blockage, but it doesn't make a difference.

    Should I just go with the under extrusion? or is these likely to be some other problem that isn't apparent?

    I didn't notice any issues with the stock extruder and the stock estep setting, but I didn't think to check the calibration.

    Why did you replace it? Likely this one is just worse than the stock one - incapable of producing the same pressure reliably.

    If you don't notice serious quality issues from a 10% change in extrusion amount (which is huge), it's probably not a good idea to make random changes to your printer.

    I replaced it because the stock one made of plastic was starting to wear at the point the filament was being pulled in, also the spring was too weak and didn't grip the filament strongly enough. There is nothing wrong with the new one... much better than the old one.

    If filament can slip in it (probably because the small gear has too little contact surface) it's not better.

    The filament isn't slipping in the gear.... the stepper motor is skipping steps.

    @R.. I had to replace mine after the plastic one broke. I chose the aluminium design of the original extruder though. This design is "double drive", pushing th filament from both sides. This has a better pushing characteristic but also is more prone to shredding the filament.

    Increasing stepper motor current can also help, if it is not already set to the maximum for that motor.

    @BG100: Ah, I misunderstood what you meant then. I think my initial tone may have been a bit hostile - sorry about that. What are the final steps per mm compared to the original extruder?

    @R.. No worries :) Original extruder was 93 steps per mm, and new one is 143.4 steps per mm. I'm using Klipper firmware and annoyingly it uses mm per step, so the actual setting is 0.00697.

    @BF100: More steps per mm should decrease the motor torque requirements so odd that it's missing steps... BTW I'd compute it exactly from mechanical properties rather than experimentally.

  • fred_dot_u

    fred_dot_u Correct answer

    3 years ago

    Consider that the extruder is skipping because it is unable to push filament at the rate you are requesting. By reducing the steps to ninety percent, you are reducing the rate by that much as well.

    Typically, a skipping extruder is an indication of clogging, but it does not have to be clogging caused by particulates jamming the nozzle. At higher rates of filament travel, one needs higher temperatures to compensate for the cooling at those higher rates.

    Consider to reduce the print speed to ninety percent of the current figure, or raise the nozzle temperature by five to ten degrees (in steps) to see if you'll get rid of the cold blocking that may be causing this problem.

    I'm using the same filament at the same temp as I used when it was stock (PLA at 200 °C), not really had a problem before the new extruder, but that maybe because the new extruder is doing a better job of pushing the filament through... so thanks for the info, I will experiment with slightly higher temp and slower speeds.

    This answer contains information on the relation of print speed and filament pressure and as such skipping steps! This should be incorporated in all those guides that tune filament extrusion length! I even forget that myself sometimes...

    Technically, it is not *clogging* if the nozzle can't handle the flow *at this temperature*. Changing the temperature changes the flow parameters (especially viscosity) in the nozzle.

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Content dated before 7/24/2021 11:53 AM