How To Stop Your Filament Breaking in the Extruder During a Print


Early in my 3D printing journey there were a few times when my filament would break or snap off in the middle of a print. After experiencing this frustrating issue a few times, I looked for information on how to prevent and stop filament breaking in my extruder during a print. If this is also what you are looking for, you’re in the right place so read on.

How do I stop filament breaking during a print? There are a few causes for filament breaking so once you identify it, you can easily fix it. For example, if moisture absorption is your cause, drying your filament should fix the problem, or if your enclosure is too hot and softening the filament too early, opening a wall of your enclosure should work.

There is nothing worse than being several hours in a print, with plenty of material left on the spool then seeing your filament breaking. Luckily there are solutions to each cause so you don’t have to settle with this happening constantly after long prints which I’ll go through in this post.

Why Does Your Filament Snap in the First Place?

Whether you’re printing on your Ender 3, Prusa, ANYCUBIC or what ever 3D printer you have, you most likely have gone through the issue of filament breaking mid print.

Sometimes it is just bad quality filament, even a reputable company can have a bad batch so don’t always think it’s down to your 3D printer. If this does happen with a few different filament though, there are a number of possible causes as to why your filament snaps or breaks off.

  • Bad storage
  • Moisture absorption
  • Too much spinning movement from spool
  • Enclosure too hot
  • PTFE tube & coupler not flowing well

Bad Storage

Filament that is stored incorrectly is a lot more likely to break in the middle of a print because it’s overall quality is lowered from the immediate environment.

Being in a humid area can mean moisture gets in to the filament, leaving filament in a dusty room can cause it to get dirty and give issues when being heated up, oxygen breaks down material through oxidization so it deteriorates much quicker.

All of these reasons are why you need to correctly store your filament when you aren’t printing. You don’t want your 3D printer filament in sunlight or stored in hot environments for a prolonged time.

Solution

One of the most common storage solutions out there is using an airtight storage box container with desiccant added to increase your filament’s lifetime and quality overall.

A good storage container that is highly reviewed and works very well is the IRIS Weathertight Storage Box (Clear).

It holds plenty of filament with no air leakage to keep your 3D prints optimally stored. It has a rubber seal and keeps your filament dry as long as the latches are secure.

You can hold around 12 spools of filament a 62 Quart storage container, which is more than enough for most 3D printer users, but you can choose a lower size if you wish.

If you get this storage container I’d also advise you to get some rechargeable desiccant to reduce the moisture in the box. You’re probably planning on 3D printing for some time in the future so getting a long-lasting solution is key.

WiseDry 5lbs Reusable Silica Gel Beads is a no-brainer. It has 10 drawstring bags and color indicating beads that go from orange to dark green when they are at their capacity. Simply dry the used beads in the microwave or oven. Also great customer service!

It’s a good idea to also measure humidity, I use the Habor Hygrometer Humidity Gauge, it’s pocket size, has readings that are very accurate and is a lot cheaper than other models.


If you want a more professional version, the Polymaker Polybox Edition II Storage Box is a premium option for the serious 3D printer hobbyists out there. With this amazing storage box people can keep filaments dry during the printing process.

  • Built-in Thermo-Hygrometer – monitors humidity and temperature inside the actual storage box
  • Carries two 1KG spools simultaneously, perfect for dual extrusion or carries one 3KG spool
  • Has two sealed off bays which carry desiccants bags or loose beads to absorb moisture

It’s compatible with all 3D printers.

Moisture Absorption

This ties into the last point of proper storage but warrants it’s own section because of how commonly this happens to be the main cause of filament breaking. There is a term called hygroscopic which is a materials tendency to absorb moisture and humidity in the air around it.

Some materials are a lot more prone to absorbing moisture such as:

  • PLA
  • ABS
  • Nylon
  • PVA
  • PEEK

Solution

There are a few solutions that I and many other 3D printer users have put to use that work very well.

You can choose one of the following:

  • Put your filament in the oven at 175°F (80°C) for 2-3 hours
  • Get a 3D printer filament approved dryer
  • For prevention, use storage and desiccant as listed in the ‘proper storage’ section above

A good low humidity value to follow falls between 10-13%

Filament Bending & Too Much Spinning Movement From Spool

Countless times I’ve seen the pressure from the extruder pulling on the spool above cause a little bit of a racket and a lot of spinning movement. This usually happens the emptier your filament roll is because it’s lighter and is moved around easier.

With enough spinning, it can cause filament, especially brittle ones to break in the middle of a print because of the bending that occurs which straightens out the curved filament.

This can be fixed with a quick solution.

Another possible cause here is that your filament is stored in an environment that is too cold, which gives filament less flexibility and make it more prone to snap.

Solution

Make sure your filament is in a good location for feeding through to the extruder. If the bending angle of your filament is too high, it means your filament have to bend too much to get through the extruder.

Enclosure Too Hot or Heat Around the Extruder

You don’t want soft PLA or another filament entering your extruder with the gripping teeth, spring tension and extrusion pressure. This combination is likely to lead to broken filament so it’s important to take the necessary steps to stop it from happening.

Solution

Open up a door or wall to your enclosure to lower the printing area temperature. This isn’t an ideal solution since you ideally want your enclosure to be closed while printing so I’d advise to try all the other methods before trying this one.

Usually the other problems are the main underlying issues, this solution is just one that reduces the symptoms rather than the cause.

PTFE & Coupler Not Flowing Well

If your PTFE tube and coupler aren’t working well enough together, it can stop letting the filament flow as easily as it should be. This means you’ll have unnecessary pressure back at the point where the filament is most likely to break or snap.

This cause in addition to the enclosure being too hot is a perfect recipe for your filament breaking mid-print. Sometimes having a good enough PTFE tube and coupler will be enough to solve the issue having to open the door of your enclosure.

Solution

Change to a better PTFE tube and coupler that are proven to work better than the factory parts. The PTFE tube and coupler I recommend is the UpperFu PTFE Teflon Tube from Amazon.

It’s made of premium PTFE material, is non-toxic and heat resistant up to 260C. The M6 & M10 fitting it comes with are highly durable and gets the job done.

The main difference you’ll see between this combination and your standard ones are that filament will flow more freely.

Make sure your tubes and fitting is installed properly and not in a way that causes the metal teeth to break off and jam inside the tube. Check that your tube is fully pushed through the coupler.

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