Top 6 Filament Errors That Cause 3D Printing Failures


It’s natural to question your slicer settings or bed dithering when a 3D print goes horribly wrong. After all, just one fun slicer setting can lead to a clogged nozzle and other 3D printing disasters.

But sometimes the problem exists at the level of the filament. Diagnosing such issues and knowing how to avoid them altogether is an essential 3D printing skill that is key to avoiding unnecessary troubleshooting elsewhere.

If your 3D printing issues arise despite good slicer and printer maintenance practices, familiarizing yourself with these filament handling mistakes could help save the day.

1. Ensure filament hot end compatibility

An overwhelming majority of clogs reported by 3D printing newbies using affordable printers can be traced to using filaments that are too hot for the stock extrusion setup. To reduce manufacturing costs, these printers allow the PTFE coating to touch the nozzle. While this saves money on expensive machined heat breaks, it also introduces the PTFE tube into the melt zone.

This is a terrible idea because PTFE starts releasing chemicals that can cause brain damage when printing filaments, such as ABS, nylon, and polycarbonate that flow at temperatures above 250 °C. In addition to the literal release of nerve agents, the rapid deterioration of the PTFE tubing also causes the nozzles to clog.

How to prevent clogged nozzles and brain damage

The solution is simple. Simply upgrade to an all-metal hot end, as explained in detail in our Ender-3 upgrade guide. This keeps the PTFE tubing safely away from the melt zone, eliminating the risk of nozzle clogging and toxic gassing. The most popular 3D printers even have heat breaks available that convert the stock hot end to an all-metal variety for a fraction of the cost.

2. Flexible Filaments Hate Bowden Extruders

Nozzle clogs in affordable printers are not limited to overheating PTFE liners. Even flexible filaments, such as TPE and TPU, which print cooler, do not work well with entry-level printers using Bowden extruders. Our Direct Drive Extruder Explainer explains in detail why this is the case, but put simply, pushing flexible filament through long Bowden tubes is difficult. It’s like pushing a rope through a pipe, which consequently requires comically high retractions.

How to print hoses reliably

A direct drive extruder is recommended for printing flexible filaments, especially if you prefer extra soft filaments with lower Shore hardness. The truly flexible variety even requires specialized extruders with shortened filament paths. But if you insist on using a Bowden extruder, you need to stick with harder flexible filaments and drastically reduce print speeds.

3. Watch out for coil tangles

If you thought tangled headphone wires were bad, just wait until you encounter tangles in the filament spools. Like the proverbial Sword of Damocles, tangled reels are ticking time bombs just waiting to ruin long prints. These tangles are not even complicated considering the relatively high stiffness of the filament. Therefore, they manifest as a single loop that eventually causes the filament to fail in power.

How to Avoid Filament Tangles

Preventing spools of filament from getting tangled requires following a cardinal rule: never let the free end of the filament back into the spool. Once that happens, it invariably slips under a stray filament loop that momentarily loosens. The next time you fish the free end it has already formed a loop which will eventually tighten up causing the filament to fail feeding which will ruin the print.

This is precisely why filament manufacturers strive to securely attach the loose end of the filament to the spool. Virtually all filament spools also incorporate a provision for threading the free end so that it is securely held. If your filament manufacturer has not implemented this feature, a 3D printable filament spool clip is the next best solution.

4. Is your filament hygroscopic?

Getting rid of the PLA drive wheel and switching to PETG is a bittersweet experience for most 3D printing enthusiasts. Although PETG is much less forgiving than PLA, what surprises most beginners is the material’s propensity to absorb moisture compared to PLA.

A wet filament can cause everything from awful print quality to a complete print failure, and the problem isn’t easily apparent unless you know what you’re looking for. Almost all advanced 3D printing filaments tend to be quite hygroscopic, with nylon and polycarbonate being virtually impossible to print without proper filament drying equipment.

How to deal with hygroscopic filaments

To start, be sure to store these filaments in vacuum sealed bags, with a cool desiccant material such as silica gel beads to absorb any existing moisture. This will prevent the filament from absorbing additional moisture during storage. However, this does nothing to extract the moisture already absorbed into the filament.

For this you need a dedicated way to dry the filament. Relatively inexpensive filament dryers designed for consumer 3D printers work just fine as long as you select the correct heating setting and use fresh silica gel beads to absorb the moisture. Food dehydrators also work wonders.

However, Nylon, PEEK, and Polycarbonate require PID-controlled ovens to some extent to reliably dehydrate these filaments. Regular ovens are cheaper, but they lack the precise temperature control that makes the difference between a perfectly dry nylon spool and a very expensive 3D printed replica of a nylon spool.

5. Always refer to the data sheet

While we have a general idea of ​​commonly used temperature ranges for different filament types, never make the mistake of assuming the correct setting for your specific filament type. This is important given the prevalence of specialized blends used by different filament manufacturers.

Depending on whether the manufacturer intends to make difficult filament printing easier or to improve its strength, nozzle temperature and print speeds can vary wildly for the same type of filament. Fortunately, these critical parameters are specified in the data sheet. All you have to do is read it and use these settings as a basis for fine-tuning your slicer settings.

6. Be careful with composite filaments

There are specialty filament blends, and then there are composite filaments. The latter involve upgrading engineered materials such as ABS, polycarbonate, and nylon with composite materials such as carbon fiber, fiberglass, and metal pellets. These composite filaments are a great way to improve the tensile strength, warping resistance, temperature tolerance and printability of engineered materials.

Unfortunately, these filaments are impregnated with up to 30% chopped glass/carbon fibers and metallic particles. Not only are these additives extremely abrasive, they can even clog standard 0.4mm nozzles. Such materials can render ordinary brass and stainless steel nozzles useless in no time.

How to print composite filaments safely

You need larger 0.6mm nozzles made from abrasion resistant materials such as tungsten carbide, tool steel, ruby ​​and even diamond to reliably print these filaments. However, these filaments lack the thermal efficiency of brass and copper nozzles, so you will need to print at higher than normal nozzle temperatures.

The devil is in the details

Now that you know how to avoid common filament handling mistakes, you’re that much closer to a trouble-free 3D printing experience. That said, it also pays to pay a bit more for quality 3D printing filament. The improved quality assurance and consistent production quality of premium filaments is a worthwhile investment considering how even the slightest deviation in filament composition can hugely affect the quality and reliability of your 3D prints.


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