Frustrated by filament jams in your hot end? Need help fixing them or keeping them at bay in the future? Stop filament jams from ruining your day (and your printer!) by following these simple tips.
We’ve all had the unpleasant experience of waiting for a print to finish only to return to missing layers, a bundle of spaghetti, blobs, or uneven filament deposition. These issues can arise from several sources, but here, we’ll focus on filament jams
Filament jams happen when the extruder can’t push filament through the hot end. The extruder either grinds the filament until it’s so thin that the gear that advances the filament is no longer in contact with it or the motor that drives the extruder stalls because it’s overloaded.
No matter what kind of extrusion system you use — direct drive or Bowden — you’ll eventually encounter this problem.
In the following, we’ll look at three common problems that lead to filament jams. The first occurs when stuff that isn’t filament gets into your hot end and clogs the nozzle. The second happens when the hot end is pushed against the bed and filament can’t be pushed out of the nozzle. The third is a loss of temperature control in the hot end, resulting in filament too cold to pass through the nozzle.
For each problem, we’ll offer some short and long term solutions. We’ll also provide some advice on what not to do when you’re desperate.
Ready to print jam-free? Let’s go!
Cause: This can happen at any time if dirt or grit gets into the hot end and plugs the hole in the nozzle. The offending substance can come from two sources, the filament itself or from dust or dirt that adheres to the filament.
Reason: Some cheap filament is made under circumstances that allow dirt to fall into the vats where the plastic is made. This dirt winds up in the feedstock from which the filament is made. Dirt can also get into the filament during the extrusion process that melts the feedstock and pushes it through a nozzle to make the 1.75-mm or 2.85-mm filament. If the plastic was recycled, bits of contamination can enter the feedstock.
Even if the filament is squeaky clean, as soon as you open the packaging, you expose the plastic to the dust and dirt from the environment around your printer.
Cause: Either liquid plastic has hardened in the cold side of the hot end or the nozzle is too close to the bed.
Reason: If the hot end has been sitting at a high temperature for a period of time, the plastic can become very fluid. When a new print is started, the material will be pushed into the cold side of the hot end, solidify, and cause a clog. If the hot end is too close to the bed, so that the tip of the nozzle rubs against the surface of the bed, this will also prevent extrusion of plastic. In both cases, the filament next to the idler wheel will be ground down by the gear that pushes the filament into the hot end. Thus, the filament is no longer pushed into the hot end.
Cause: Bad temperature control of the hot end.
Reason: There are two major reasons why the temperature of the hot end can vary: physical (airflow) and electrical (thermistor failure, weak or broken wiring to the thermistor, or broken or burnt wiring). These can be vexing problems because they can be intermittent.
The methods described above for solving extrusion problems are simple and are intended to be useful for a majority of situations. We do not recommend any action not approved by the makers of your printer or hot end.
Looking online, it’s easy to find drastic methods for cleaning out hot ends. These are last-ditch efforts that can end badly. If in doubt, contact the manufacturer.
Filament jams are annoying, but they can be solved with a little time, effort, and a few tools. Having these tools and tricks available will help you to print successfully even in the worst of times!
License: The text of "Filament Jam – 3 Easy Fixes" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.
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