Is It Safe to Leave A 3D Printer on Overnight? (Answered)

If you have a 3D printer, chances are you want to make the most out of it. Letting it print overnight is one of the easiest ways to speed up builds.

But, the question is, should you? 

Unfortunately, no matter how tempting it is to leave a 3D printer on overnight or unattended, it can create risks. Most manufacturers strongly advise against doing so. While there are some management and risk-reduction steps you can take, leaving a 3D printer on overnight always creates risk. 

Can You Leave a 3D Printer on Overnight? 

Most 3D printers are not made to run without supervision. In addition, 3D printers can present a fire hazard. In fact, there are many examples of 3D printers left alone to print which turn into a fire hazard.

While that isn’t always the case, your 3D printer may not be safe to leave alone. That’s especially true if you’re printing in an enclosed room. Here, fumes can build up overnight so that your room is unsafe to enter. 

However, there is a large community of people who do run their 3D printer overnight and without supervision. In fact, most manuals suggest not leaving your 3D printer unattended for long. However, many still do so.

Most use mitigating efforts such as 3D printer fire suppression tents. These can reduce the risk of fire and of dangerous fumes. However, no printer manufacturer will recommend this.

Instead, most strongly recommend against running your printer without real-time supervision. This advice stems from the fact that any 3D printer can snag, catch, fall, or otherwise burn out – creating a potential fire hazard

3D Printers and Fire Hazards 

3D printers are a fire hazard. That is true of any device with working temperatures that sometimes exceed 250 degrees.

However, some 3D printer models are more susceptible to combustion than others. For example, the Anet A8 3D printer has a history of combustion – and you can easily find photos of the model burnt out on Google Images. On average, 3D printer fires are rare. 

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Here, several things impact fire hazards in 3D printers. The first and most important is build quality.

Every 3D printer has a thermistor to measure the operating temperature of the 3D printer. Most include a thermistor and heat cartridge instead of a bulkier thermostat.

With poor build quality, the thermistor sensors can come loose – which may result in the 3D printer overheating and combusting.   

That also holds true with wires and cabling. 3D printers can run very hot. Over time, cables can weaken and reach melting point.

If you leave your 3D printer running for 18-20 hours, including a long stretch of unsupervised time, those cables could damage to the point of baring wires. That might not result in a fire right away, but eventually, it will. 

An electrical fault, such as a short in a wire can also cause a fire. Here, a short causes a spark, usually in a motor. It keeps sparking because the motor keeps running.

Eventually, the motor catches fire – which can spread to other parts of the room. That’s especially important as many people leave 3D printers sitting on wooden tables.

Because many people leave flammable agents such as lubricants, cleaning agents, paint, resin, etc., near their 3D printer, even a small printer fire can quickly get out of control. 

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It’s highly unlikely you’d get a fire from the 3D print process. Plastics are both not very flammable and more likely to melt if left in contact with the extruder tip while it’s still warm. 

8 Safety Measures to Take Before Leaving Your Printer Unattended 

It’s never advised to leave your printer unattended.

However, if you do, it’s important to take safety measures to reduce any potential risk. 

1. Machine Auto-Shut Function

Most 3D printers have an auto-shut-off function. It’s important that you use them.

This requires checking the manual and potentially creating a script to automatically turn the 3D printer off when the build is complete.

In most machines, this will be relatively easy. However, it varies per machine, and may be more difficult depending on the strength of the firmware that comes with your printer. 

This varies per printer. Check your manual and set it up. 

2. Remote Monitoring Systems

Remote monitoring systems like webcams and software can offer a lot of assurance when you leave your 3D printer unattended.

For example, a webcam allows you to check up on the visual status of your webcam on demand. That won’t do much good if you’re going to sleep, however, it will if you’re going to work.

Applications like Octoprint offer dependable remote monitoring for most 3D printers. This allows you to monitor, control, and shut off your 3D printer if it exceeds certain settings. That adds a good measure of safety, providing your hardware is measuring properly.

Octoprint also offers remote monitoring, including an embedded webcam feed, progress updates, and GCode visualizers, so you can see what your printer is doing at any time. And, with remote start/stop/shut down functions – you get more control over turning the printer off even if you’re not in the room.

While that doesn’t help much if you are sleeping, it is a good additional control if you’re leaving the house or going to work. 

3. Thermal Runaway Protection Enabled 

Thermal runaway protection is a setting on most 3D printers that allows you to reduce or prevent most fire hazards.

Here, the printer simply stops the print in case anything is unusual about the readouts from the thermistor. For example, if the readings are too high, if the readings are too low, or if the readings stop altogether. That prevents issues like a dislodged thermistor or sensors resulting in a fire. 

Thermal runaway normally happens when the thermistor is misaligned, dislodged, or faulty. Luckily, many 3D printers actually have it activated by default.

For example, Prusa and MakerBot use thermal runaway protection by default. Others, like Marlin and Ender 3D printers require you to turn the function on.

Make sure the function is on and check your manual to see what thermal runaway protections your printer actually comes with. 

Why This Should Be Active

If you don’t have thermal runaway protection active, it can result in issues like fire.

Thermal runaway protection is designed to shut down prints if something is off. That means it will react to faulty hardware.

Otherwise, you are relying on the thermistor being in good working condition. You also need it to be properly aligned.

Common Problems That Trigger TRP 

Thermal runaway can be triggered by a lot of things, primarily faulty hardware. These triggers include:

  • Electrical shorts 
  • Plastic sticking to the hot end and catching fire
  • Faulty wires or cables melting 
  • Electrical surges
  • Misaligned thermistor 
  • Loose thermistor
  • Faulty thermistor
  • Broken heat cartridge
  • Mistakes with heat settings 
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4. Place Printer Away from Flammable Objects 

Many printers are hot. In fact, some print at temperatures similar to an oven. It’s important to keep them away from flammable objects.

That means putting 3D printers on a ceramic or metal surface or tray in a well-ventilated room. You also want to ensure that paint, resin, cleaning supplies, etc., are not stored nearby.

If you do store these kinds of materials in the same room, try to store them in a metal or other filing cabinet, where they will be less affected if something does go wrong. 

5. Smoke Detectors 

A smoke detector will let you know if something goes wrong, so you can react quickly if there is a fire, even if you have a smoke detector and carbon monoxide detector in the house.

Here, you’ll want to install both or a dual detector in the room with the 3D printer. This ensures you’re alerted of a problem as quickly as possible in case something goes wrong. 

If you do plan to leave your 3D printer on overnight, you might want to consider a smart smoke detector. These devices send alerts to your phone – which can wake you up.

Then, you can react as quickly as possible to a potential fire and avoid disaster. 

6. Fire Extinguishers

It’s important to have a Class C Fire Extinguisher on hand whenever running potentially flammable machinery. Class C fire extinguishers use dry powder chemicals or carbon dioxide to suffocate a fire, which may still be connected to live power.

If you do have a fire, it’s also a good idea to first cut power to the room using the breaker box. This ensures that any electrical power which might be feeding the fire is cut off. It also reduces the risk of the fire causing shorts and potential fires in other parts of your home. 

For the best results, buy a fire extinguisher and take a class on how to use it. Most local fire departments offer free courses on basic fire management including the proper use and storage of a fire extinguisher. 

7. Enclosure

Enclosing your 3D printer in a fire-resistant cabinet or tent can do a great deal to reduce the risks associated with leaving it unattended. These are often sold commercially.

However, you still have to make sure your 3D printer gets enough ventilation. In addition, it’s almost always a bad idea to store a 3D printer in a cabinet, where it might overheat wood or composite.

3D printer enclosures

  • Reduce the risk of fumes escaping into a room. You can vent into a controlled area 
  • Keeps humidity away from the printer
  • Helps control the temperature of the print
  • Minimizes heat loss from the heat bed, which can reduce energy usage
  • Prevents objects or pets from damaging the printer

8. Print at Lower Speeds and Temperature 

Printing at a lower speed allows you to reduce the temperature of the print – to a certain point. However, this reduction will not be enough to make it safe to leave your printer alone without taking safety precautions.

On the other hand, it will reduce the potential risks of faults and issues from overheating. In general, the slower you print, the better it is for the machine and the higher quality the print will be.

However, you may also want to choose to print with something that becomes workable at a lower temperature – such as PLE instead of ABS.

For example, PLE allows you to print as low as 180 C if you have a heated bed. ABS usually requires at least 240 C. 

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You Can Pause It Overnight Instead

Most 3D printers come with built-in start/stop and pause functions. Providing you don’t cut power or lose the saved print data, your printer can then pick back up where it left off.

That allows you to safely print larger projects, even when they take more time than you have in one day. 

That’s also a much better alternative to fully stopping the 3D print mid-way. For example, if you do so, you’ll likely lose the print. It’s almost impossible to pick back up where you left off, unless you’re using multi-part files. 

How Long Can You Pause a 3D Print? 

Theoretically, there’s no limit on how long you can pause a 3D print. However, your printer has to maintain power to retain the saved file and progress unless your printer has a save function or you can save to your computer.

In addition, it’s important that the print is not removed, moved, or jolted. If it does come loose, you’ll likely have to restart the print. 

Also, the longer you wait, the more likely you’ll have to clean the print before continuing. To do so, carefully wipe the top of the print down with an alcohol wipe to remove any built-up dust. Make sure you don’t jostle it loose.

Then, allow it to dry and pick up from there. 

Related Questions

If you still have questions, these should help. 

How often should I give my 3D printer a break? 

Most 3D printers do not need breaks to run properly. In fact, many people run printers 10+ hours per day, every day.

However, the more you use your 3D printer, the more important it is to run maintenance to ensure everything is aligned and in place.

A misaligned belt can do a small amount of damage on a 1-hour print. On a 10-hour print, it can ruin your machine. 

What temperature is best for 3D printing? 

Temperature settings should wholly depend on the material you are printing. Check what you are printing, your bed heat, and your ambient temperature. Then set the temperature accordingly.

In most cases, you can get away with a lower temperature by running a slower print. However, running your 3D printer too cold can cause under extrusion and extrusion skipping – which will ruin your print.  

How long to let 3D print cool? 

It’s normally recommended to let a 3D print cool for 5-10 minutes after the print finishes. However, recommendations change per material and based on your fans.

For example, if you have low ventilation and a heated bed, you might want to give it a few minutes longer. 

Final Thoughts

If you still want to run your 3D printer overnight, it’s important to understand that you are taking on a risk. Make sure you take steps to reduce risks before 3D printing overnight. In addition, you should notify a family member or friend as a precaution if no one is in the home to attend to the printer. 

It’s never recommended to run a 3D printer unattended and that includes overnight or when you are not at home. If you do so anyway, make sure you try to reduce that risk as much as possible.

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