Increased issues with filament grinding

  • I have a FlashForge CreatorX (MakerBot clone) that's been working fine for about 15 months. Int he past month, I started noticing "thin" layers in some of my ABS prints. I finally tracked the issue down to the extruder gear grinding the filament (after a while, enough filament had ground off that the gear teeth were filled with plastic). I cleaned the gear twice before giving up on ABS and switching to PLA. Everything seemed ok until the PLA started doing the same thing during an overnight print (thin layers on prints, audible skipping during filament feed).

    Raising the temperature on the extruder seems to fix the problem, but I'm now extruding PLA at 242 °C, much higher than I used to need. I worry that continued printing at this temperature will increase wear on the thermistor and increase my chances of clogging PLA in the gear (an issue I've had twice before).

    Are there any common issues that cause this issue of filament not feeding properly? I've tried cleaning out the extruder head with wire and there don't seem to be any clogs…

    Did you change filament vendor? Maybe this could be an issue.

    If you can remove the feed pressure and feed filament by hand, what does the resistance feel like? If it is high, you may need to clean the head.

  • After disassembling the extruder mechanism, I tracked the issue down to a clogged extruder… though not in the way I'd expected. A (previously?) common method to drop filament down to the hot end and create a heat-break between the heater and the extruder gear was the use of a PTFE (Teflon) sleeve. Over time, this sleeve can become clogged by filament that has melted and degraded/carbonized, sticking to the "nonstick" walls. This creates a bottleneck for the new filament, preventing smooth extrusion.

    Carbonized filament clogging tube.
    Location of heat-break on used tube.

    My printer came with two replacement tubes. Swapping those in for the old, clogged tubes resulted in instantly improved printing… sorta like getting a new printer! Print temperatures are back to normal and everything operates fine. I was also able to drill out the carbonized filament from the old sleeve, though I doubt I'll reuse it. I found replacement sleeves on Amazon here and an alternative, all-metal extruder assembly manufactured by Micro-Swiss. I'm not sure if you'd run into clogging issues on the all-metal one, so perhaps staying with the PTFE tubes and replacing them occasionally is a better way to go.

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

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