Filament issues like tangles and overlaps can disrupt a 3D print, but they’re often misunderstood. While they may look similar, they have different causes and solutions.
Tangles
A true tangle occurs when the filament loops under itself, creating a knot that prevents smooth unwinding.
Causes:
- The filament end is left loose and re spool incorrectly, its either caused by human error from factory towards start of spool where its accidental let go and roughly re-spool back onto the spool or by the user when unloading/loading materials where end came loose before feeding
- Removing and rewinding the spool carelessly
Effects:
- The extruder hits a hard stop due to the blockage.
- The filament physically cannot move without untangling.
Prevention:
- Always secure the filament end when handling spools
- Before printing, manually unwind a few rotations to check for loose loops from the factory if you believe they may been a tangle or watch initial couple metres.
- Be cautious when manually rewinding filament, especially in an AMS system.
- Newer printers have auto tangle detection or for older printer you can install additional add-ons which can monitor filament clog and tangle such as SFS which can detect which can save print and hardware.
Most tangles mid way through a spool are due to user handling rather than manufacturing defects, as usually if tangle does occur it only occur at start of spool when factory work miss spool into holes.
How to untangle:
Overlaps
An overlap happens when filament crosses over another layer without forming a true knot, causing resistance or snags. Two loops stacked or squashed on top of each other.
Causes:
- Neat and tight factory winding can sometimes cause this issue, especially if the spool has imperfections that lead to uneven spooling. Because the filament is wound tightly and runs parallel to the spool edges, tension can cause the winding to shift and overlap. This usually occurs at the start or end of the neat winding. This is more issue with more lighter density materials which require materials to be winded more tightly to fit a standard 1kg spool.
- Can be also more common in re-fill filament spool, as if the filament edges have shifted before installing the filament side it can cause filament to shift causing overlap issues on the edge of the spool.
Effects:
- Increased tension but can often be pulled through with minimal effort. (older printer or weaker extruder may have issue causing extrusion issues in the print).
- Rarely causes a complete stoppage unless severely tight or weaker extruder set-ups, newer AMS/CFS type system with buffer system from our experience is able to overcome this tangle as long filament spool is more full as lighter spool the force to self untangle can cause spool to come loose from un-secure roller/holders.
Prevention:
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Avoid actively drying materials while printing, as this can cause the spool to expand or deform. It's best to dry the filament before use and allow the spool to cool down inside the dryer (running on the lowest setting) or in a dry box. (You can print some filament clamp which help from cardboard from shifting while drying)
This recommendation is based on our experience. We've seen no issues reported by users with PLA materials, which typically don't require drying. Most of these cases involved newer batches with neater winding, being actively dried.
- Newer printers have auto tangle detection or for older printer you can install additional add-ons which can monitor filament clog and tangle such as SFS which can detect which can save print and hardware. This should prevent printing air and allow operator to loosen spool to resume the print. Another option is having buffer extruder externally to help filament feeding and overcome the overlap and reduce the strain on toolhead extruder such as Mellow LLL Plus or DIY Project such as Dual Nightwatch if you have a weaker toolhead extruder.
