What Happens When Filament Runs Out? How To Save Your Print!

A 3D print can take anywhere from an hour to days to complete. Fortunately, most printers allow you to adjust the settings to speed up the print. Speeding up a printer is usually not recommended as that can have unintended consequences but that is a topic for another day.

Today we’re focusing on what happens when your filament runs out in the middle of a print. If you ever have a project stretch over a lengthy period, this will likely happen to you. If it does, you want to be prepared so you know what to do. Either that or your print will be ruined!

One of two things will happen if a printer runs out of filament. If the printer has a run out sensor it will automatically pause the print to allow for the replacement of the filament roll. Once the roll is replaced it resumes printing. If the printer does not have a run out sensor, it has to be paused manually for the roll to be refreshed or else the printer will keep working without extrusion, potentially leading to the failure of the print.

Whether you’re a pro who’s been printing for years or you’re a beginner who just picked up a 3D printer a month or two ago, this article will give you the information you need to take the necessary steps to prevent a print fail should your filament run out.

On a side note! If you’re looking for a reliable and high-quality 3D printer, we highly recommend the Official Creality Ender 3 V2 Upgraded 3D Printer (Amazon Link).

This printer is an upgraded version of the popular Ender 3 model, with a range of new features and improvements that make it even easier and more convenient to use.

The Ender 3 V2 is an excellent choice for beginners, kids, and experienced users.


What Does Filament Run Out Mean?

Filament run-out means all the filament in the printer has been used up in the process of printing a model. This happens when there is not enough filament to complete the print. Filament comes in variable sizes of which the most common is a 1 kilogram spool. Quite often the spool of filament will fall short of print requirements forcing a change of spools. 

This can and will likely happen when you’ve been printing 3D models for long enough. Maybe you have a little bit of filament left over from a previous model. You decide to start on a new smaller project which you’re sure won’t take much but in the end it turns out you miscalculated.

Also, prints can go for more than a day. It’s impossible to watch the print the entire time even if you wanted to. You’re going to be in and out and as luck would have it, the time when you’re away is when you’re most likely to run out of filament!

What Happens When A 3D Printer Runs Out Of Filament?

One of two things will happen if a printer runs out of filament. If the printer has a run out sensor it will automatically pause the print to allow for the replacement of the filament roll. Once the roll is replaced it resumes printing. If the printer does not have a run out sensor, it has to be paused manually for the roll to be refreshed.

There is a distinction is between having a printer with a run out or filament break sensor.

A run out sensor is there to tell your printer to stop printing if there is a problem with the filament. This might be getting stuck or running out. Most newer model printers are equipped with built-in run out sensors. 

If the problem is a run out, the printer resumes where it left off once you’ve swapped the empty spool for a new one. Things get a little more complicated with printers that do not have run out sensors. This is the case with most older model printers.

If you are not there to pause the print, the printer will still print, only without any filament! The printer can’t detect there’s no filament being extruded. The printer head continues moving and printing as if there is a filament, however. It will print until it goes through the all the instructions of your model resulting in an unfinished print.

This is where you now need a little know-how to resume your print. In most cases, you can’t simply reload your printer and resume your print because the printer has “lost its place” since it kept on printing after it ran out of print.

So, do you trash your half-finished print and start all over? Not yet!

How Do I Save A Print That Ran Out Of Filament? Simple Steps Listed!

Saving a print that ran out of filament is possible although potentially difficult depending on the print. There are several steps involved from keeping the print on the print bed to editing the g-code of the model. 

Step 1: Keep the print in place

The first thing to do is to make sure the print stays on the print bed by keeping the bed heated. You want the print to stay in the exact same place.

Step 2: Find the z height

Find out where your print failed at. This tells you where your print needs to start from. Measure the highest z-height with a ruler. 

Step 3: Edit the g-code

Get the corresponding g-code for your z height. Copy and paste the g-code into a new document where you can edit out everything before the failed layer. Careful you don’t delete your printer settings. Save the new edited g-code and upload it.

Step 4: Restart your printer

Resume the print making sure you position your nozzle so it doesn’t start where it might crush your model.

Restarting a failed print is a complicated process. It’s far much easier to avoid this happening in the first place.

How Do You Stop Filaments from Running Out?

Using a combination of your slicer software and proper tracking of your filament use will reduce the likelihood of run out. The second thing to have is of course a run out sensor. If your printer does not have one you can buy or make a cheap one and retrofit it to your printer. 

Also, we highly recommend that you check out our post “How Much Filament Do You Have Left? Tips & Tricks Listed!

How Long Can PLA Filament Be Left Out?

PLA has a shelf life of up to 3 years depending on what brand it is and the conditions under which it is stored. Good quality brands have longer lifespans and storing it in airtight containers helps to extend the lifespan.

Like most filaments, PLA is hygroscopic. Leaving it out in the open exposes it to humidity. Moisture absorption is the main reason a filament becomes weaker and in extreme cases, unusable. Direct light can also have the same effect. 

We recommend that you check out our post “How Long Can Filament Be Left Out? Tips On Storing & Using Leftovers!

Storing in airtight containers away from direct light ensures PLA lasts as long as you need it to. Thermoplastics like PLA have been known to still be usable even after 15 years. 


I am a very well experienced techie civil engineer who's extensively interested in 3D printing technology and even more captivated by the potential of 3D printing livable structures

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