WARNING – How Safe is Your Desktop 3D Printer?

by Jason King on February 28, 2015

Safety FirstA little while ago I wrote a blog post about the True Costs of 3D Printing at Home.

This was by far my most popular, liked and retweeted post to date.

The reason was partly because “How much did that cost to make?” is the most common question I’m asked about 3D printing.

I also believe it was because the issue of 3D printing costs had never really been properly addressed, up until now that is.

Another desktop 3D printing related issue which I believe to be more important than cost and which again, never seems to be fully addressed is the issue of safety.

Type ‘3D printing safety’ into Google and you’ll be swamped with articles discussing PLA vs ABS fumes and you’ll also find some information about airborne particles too.

However, although these potentially toxic emissions are quite rightly of real concern to many people, they can easily be addressed (ventilation for example) and there is more to 3D printer safety than air pollution.

Now, I’m not pretending to be an expert in 3D printing safety, but who can honestly claim that they are, bearing in mind that 3D printing technology is moving so fast and there is little real data regarding most aspects of safety.

What I do want to achieve from this post though, is to make you aware of some of the main risks that are quite often not even talked about and to give you some pointers in how you can minimize or eliminate those risks.

Whenever I write a post like this I have to make some assumptions. The only assumption I’ll make is that most desktop 3D printer users will be using an FFF style 3D printer, or more basically a printer which uses melted plastic to build objects layer by later.

As we’re only talking about desktop 3D printer safety for home use, I think this is a fair assumption. At least until other 3D printing technologies become more Mainstream and Affordable.

On the subject of melting plastic, let’s start with the high temperatures involved in FFF 3D printing.

High Temperatures

Burns

The temperatures used to melt plastic in FFF printers aren’t particularly high, but they are high enough to cause damage when things go wrong.

Typically you’ll want to be using temperatures of 190 to 260 degrees Celsius at the hot end of your extruder in order to melt plastic to the right consistency for 3D printing. The temperature you choose is dependant on the type of material you’re using and the kind of finish you require.

Temperatures of this magnitude are more than enough to give you a very nasty burn. Luckily the hot end of most 3D printers is fairly small so you’re unlikely to cause yourself any life threatening damage from burns.

However, I have burned myself many times when removing plastic from the nozzle while it’s hot, so be careful as it happens a lot and isn’t pleasant.

When printing with PLA you don’t really need a heated build plate but if you do the temperature should be relatively low. With ABS you’d typically use a higher build plate temperature of around 120 degrees Celsius.

Again, this is hot enough to burn you and the surface area is much larger than the extruders hot end. So, if you’re really worried about burns, just stick with PLA and you shouldn’t even need a heated build plate.

Fire

As with any electrical equipment, especially that which contains heating elements like your 3D printer, there is some risk of fire.

If you have ever seen the film Fahrenheit 451 you may already know that this film (or at least the original book) was named after the temperature which paper supposedly catches fire and burns.

This value is what we call the auto ignition temperature of paper, which is the temperature which paper can burn without a flame.

However, there is no authoritative value for this as there are many other variables which affect this value, but realistically the auto ignition temperature of paper is around 30 degrees Fahrenheit higher than this.

So why are these numbers so important to 3D printers?

Hot SurfaceThe reason is that 451 Fahrenheit is about 233 Celsius, which is well within the range of temperatures the hot end of your extruder will be.

Just to be safe, it’s best to keep paper and any other combustible materials well away from your 3D printer.

The auto ignition temperature of PLA for example, is around 388 degrees Celsius, but as with paper, different people say different figures. Most importantly though, this temperature is well above the temperature your hot end should reach.

The plastic you’re printing is very unlikely to ignite even in the case of a tangle of plastic around the hot end resulting in a Failed 3D Print, but if your Thermocoupler Fails then there’s usually nothing to stop the hot end temperature from running away and heating up well above the temperature you have set it to.

This could potentially be very problematic, especially as most desktop 3D printers contain few or no safety features (more on this later). To add to this, many desktop 3D printers are still made from good old fashioned laser cut plywood, making them quite combustible themselves.

Given all of this, I’d highly recommend you never leave your 3D printer unattended while in use. Now I realise that when you have a 20 hour print you can’t sit and watch it the whole time. But at least check on it regularly, don’t go too far from it and never leave the house/office with your 3D printer running.

An alternative to physically checking your 3D printer is running as expected is to do what I did and fit a Small Wireless Camera. This allows you to keep an eye on your print job from anywhere in the same building.

Fitting a smoke alarm in the same room and having a fire extinguisher handy would also be a very good idea. You can use dry powder but this can damage delicate electronics, so CO2 is probably best for our purposes.

In summary, keep flammable materials away from your printer, never leave it unattended whilst printing, fit a smoke alarm and keep a small suitable fire extinguisher handy.

Toxic Emissions

Fumes

As I stated earlier, most literature discussing 3D printer safety only mentions fumes and particles. There are many different opinions on both of these, but not so much solid data, so I’ll try to summarise the issues here.

The two main types of plastic used in FFF 3D printers are Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA). Both give of fumes and particles when they’re heated.

PLA is an organic material, often made from corn starch or sugar cane, making it quite safe to use as far as fumes are concerned. Currently there is very limited official information available about the effects of PLA on our health.

ABS is petroleum based, making it potentially more toxic than PLA when heated. The reason I say ‘when heated’ is because LEGO bricks are made of ABS and let’s be honest, kids have been chewing on LEGO for years. The potential health issues come from the decomposition of ABS into fumes and particles when it is heated up.

A few studies have shown ABS fumes to be toxic to rats and mice and there is a fair chance that ABS fumes are more harmful than PLA fumes, mostly due to higher levels of emissions and higher toxicity.

Particles

As well as emitting fumes, heating ABS and PLA also emits particles. The problem with these particles is that they’re tiny, often well below 100 nm in diameter. Particles of this size are called Ultra Fine Particles (UFPDs).

When we inhale UFPs they can end up deep inside our bodies and even make their way to our brains. They can then cause inflammation in our respiratory system or penetrate into our lungs as well as entering our bloodstream.

3D Printing VentilationRecent studies have shown that ABS emits around 10 times as many UFPs as PLA when heated, again making ABS more likely to affect our health than PLA

So, given this information about fumes and particles what can we do to minimize the risks?

There are such things as High Efficiency Particulate Arrestance (HEPA) filters, which could filter the air before it leaves the 3D printer.

However, some particles emitted by 3D printers are as small as 15 nm, whereas HEPA filters typically filter particles larger than 300 nm. This would be like using a wire fence to stop a bullet and is unlikely to help much.

Using a good ventilation system will dramatically reduce the fumes and particles we inhale. This is probably the best solution, combined with using PLA rather than ABS, which has fewer, less toxic emissions in the first place. Failing this, at least use your printer in a well ventilated large open space.

Ventilation systems (and incidentally 3D printer general performance) improves with an enclosed build area. This sounds like a great solution, but there is a problem with this.

Stratasys has Active Patent US6722872, filed on 23 June 2000, preventing anyone from selling a completely enclosed 3D printer. This patent isn’t due to expire any time soon so unless manufacturers license this from Stratasys (probably at great expense), we won’t be seeing many of these printers from any other manufacturers for another 5 years or so.

Moving Parts

By the nature of how they work, FFF 3D printers have quite a few moving parts. These are mostly stepper motors, pulleys, threaded rods, carriages and small fans.

Whilst parts like fans are usually very low torque and pose little risk, stepper motors are high enough torque to be able to trap your fingers.

Combine the risk of trapping your finger with a 250 degree Celsius nozzle and you could easily find yourself with a nasty trap and burn combination.

Whilst talking about 3D printers and children, Philip Cotton, 3D Printing Teacher of the Year 2014 recently stated:

“They [3D printers] have extremely hot extruders that can cause extreme burns and also moving carriages that can cause injury if children get their fingers trapped in them”

He suggests that children using 3D printers unsupervised should be at least 14 years old.

3D Printer WarningsI believe they should still receive proper training, whatever their age.

For example it’s useful to know that in the case of something going wrong you can move the 3D printer carriage manually along the X, Y and Z axis as long as the stepper motors are disengaged.

However they can be very difficult to move when engaged, so turning off the power will usually allow you to free yourself easily.

Long hair could be an issue too. It’s not something I have to worry about myself but these moving parts would have little difficulty in trapping your hair as most printers are not enclosed.

So, keep your hair and fingers out of the way and supervise children while they use the printer and you should be able to minimise the risk that the moving parts could cause.

It’s also useful to note that 3D printers can spring into life unannounced too. When the extruder reaches it’s required temperature before a print the carriage will automatically move ready to start the print. If you happen to be having a little clean around the extruder at this point you could easily be caught out.

High Voltages

As with any electrical equipment that uses mains voltage there is always a risk of electric shock or the possible outbreak of fire.

The voltages in the exposed parts of a 3D printer shouldn’t usually exceed 12v to 24v which could give you a little shock but is generally considered safe. Most voltages in your 3D printer will be much lower than this.

However, if you’ve ever owned a 3D printer you’ll know that sometimes you’ll be required to take it apart to remove trapped pieces of plastic or diagnose and fix a broken part.

You must remember to switch of the 3D printer and unplug it completely from the mains whilst carrying out any of this work. I know it sounds obvious but it’s very easy to forget and easy to think you’ll be alright if you’re careful.

However, when you remove certain covers you could exposing yourself to voltages of upwards of 220v AC, which can be deadly. So never take the risk if you’re unsure.

High VoltageThankfully my MakerBot Replicator 2 uses an external transformer so although it plugs into mains voltage, the highest voltage within the printer itself is 24v.

I imagine most 3D printers of this type use a similar external transformer, but check your particular model.

The risk of fire caused by these voltages as well as mains transformers shouldn’t be any higher than with any other mains powered electrical equipment, but desktop 3D printers still have very few if any safety features (more on this later), so don’t expect much from them in the way of protection.

The precautions you should take against electrical fires are similar to those mentioned above where we talk about the risk of high temperatures, so re-read that section if you’re worried and again, never leave your printer unattended while it’s switched on.

Tools and Chemicals

As well as heat, toxic emissions, moving parts and high voltages there are some secondary risks to 3D printing which could be more dangerous than the 3D printer itself, especially for children.

These are the other tools and chemicals that are likely to form an important part of your 3D printing experience.

Some of the tools you will use on a daily basis could cause you a serious injury. Knives, pliers, metal scrapers, even sharp bits of plastic. These are just a few examples.

I’ve injured myself more than once trying to remove a stubborn object from the build plate with a metal scraper or knife blade.

I believe that this is where the real risk of injury is and if children use your 3D printer you should consider banning them completely from removing stubborn objects from the build plate and any post processing that follows.

That brings us to some of the chemicals that you’re likely to use. If like me, you have given up using blue tape on your build plate and Use Hairspray Instead then you should note that hairspray is effectively airborne glue.

You don’t really want to be inhaling this too often as us 3D printing people are inclined to use the strongest hairsprays we can find. Don’t forget that hairspray is highly flammable too.

As part of my post build processing I’ll also sometimes use Copper Spray Paint and Silver Guilders Paste or something similar. Again, you should be careful of this and use it only in a very well ventilated area.

Acetone LiquidAlthough I don’t currently print using ABS, for some of the reasons explained earlier, I do still use acetone for applying guilders paste to my prints.

Acetone dissolves ABS and most people who print using ABS will have some of this handy for cleaning.

Acetone is toxic and if you use it for vapour polishing then it’s even more toxic as it emits lots of fumes in a confined space.

Vapour polishing is the process of gently heating acetone (or similar chemical) to create a vapour around your ABS print. This melts the surface slightly, allowing the natural surface tension to smooth the surface of your object.

I have never recommended this, as it involved heating up an already toxic and highly flammable liquid to deliberately create fumes. To me that is a little crazy and there are far safer ways to create amazing finishes on your 3D prints.

So as far as the use of acetone is concerned, use it sparingly if you have to. Be careful of the fumes and remember it’s highly flammable, so never heat it deliberately or allow it to be exposed to heat of any kind. This applies to any other chemicals of a similar nature.

3D Printed Objects

So far we’ve covered the safety of desktop 3D printers themselves and some of the equipment you’re likely to use along side them, but what about the safety of parts and products you can make with them?

There are a number of safety issues with the objects we can all create using our desktop 3D printers. The obvious ones are intentionally dangerous items, such as Firearms, knives, knuckle dusters and even Drugs.

LiberatorWe see stories about these all of the time in the press and they are something we cannot ignore when considering 3D printer safety.

If other people have access to your printer, you may never really know what they’re using it for.

There’s also an issue of 3D printing items which come into contact with food. This isn’t simply a matter of avoiding potentially toxic plastics as plenty food safe plastics are available for 3D printing, for example colorFabbs FDA Approved XT-Copolyester which I’ve used myself.

Something that’s easy to miss, is that even when we use FDA approved (food safe) materials for food and drink use, by the very nature of 3D printing the objects we create have very inconsistent surfaces with tiny holes throughout them.

Many items we make will leak, but the real problem is that these inconsistencies and holes (lack of a smooth surface) are a breeding ground for bacteria and any amount of cleaning, even in a dishwasher will not remove all of the bacteria that builds up.

On the subject of dishwashers, many 3D printed plastics wouldn’t survive a dishwasher. I use hot water of around 60 degrees Celsius to deliberately melt PLA so I can bend and manipulate it for some objects.

Imagine making a cool new mug for yourself in PLA plastic and then adding hot coffee to it. I’m afraid it would very likely collapse at this kind of temperature and literally leave you in hot water.

For my final issue, I’m going to use 3D Printed Aviation Components as an example. Now I know we’re not likely to be printing these at home, but I think the aviation industry helps make a good point.

3D printed parts are not very consistent. It’s far easier to make consistently identical parts using traditional manufacturing methods than it is using additive manufacturing.

When we’re considering highly Safety Critical Components (for example in the aviation industry) then this can be a real problem. We can design, make and test a component successfully, but the next one we make may have flaws in it and could have serious consequences when used.

To help alleviate this problem the aviation industry uses scanners and X-ray machines to monitor the production of 3D printed components as well as the finished items. It is notoriously difficult to have aviation components and processes approved by the FAA and quite rightly so.

For us mere mortals using desktop 3D printers at home, this just emphasises the point that the things we make may not be safe or fit for purpose, from intentionally dangerous items, to coffee cups, to parts for out push bikes or cars which we may be tempted to make and use.

Safety Features

Think of all the electrical items we use on a day to day basis in our houses. Many of them have obvious or hidden safety features built into them.

For example, opening the microwave door while it’s running will automatically switch it off. Many irons nowadays have movement sensors so if you leave them unattended and switched on they will switch themselves off after a short time.

With all these fumes, particles, high voltages, moving parts and heat sources in our desktop 3D printers we’d expect a certain level of safety features in them too.Fuse

Well, I’m sorry to tell you that in the majority of desktop 3D printers there are no safety features to speak of, beyond the obvious fuses and partially enclosed printing areas.

Having already heard about this being an issue, for the purposes of this article I set out to find out what safety features are available in desktop 3D printers.

I was surprised and slightly shocked when I almost drew a complete blank, finding very few or no safety features on most desktop 3D printers.

This is partly because the emphasis at the moment in the home/desktop 3D printer market is low price and good quality prints. Safety features in the eyes of the manufacturers just add unnecessary costs which makes them uncompetitive.

Take my MakerBot Replicator 2 for example, which isn’t a cheap device. I started by looking at the supplied user manual and was pleased to find a ‘Safety and Compliance’ section at the back. That was until I realised it was only concerned with ensuring the printer didn’t interfere with radio or television equipment. Nothing about toxic fumes, trapping you or burning your house down.

In the manual and on the printer itself I did find a CE Mark, which I found out means that the Replicator 2 complies with all applicable EU requirements, such as safety, health, and environmental protection, but what this actually means is a mystery.

There was also an Intertek Mark  in the manual and on the printer, which to be honest I’d never heard of. A little research revealed that this ensures the quality and safety of products, processes and systems. Again, that could mean almost anything.

A close inspection of the 3D printer itself also revealed a few stickers here and there warning of trapping risks and hot surfaces. These stickers are a good start, but they are not exactly safety features.

My Google searches for 3D printer safety features only revealed a few desktop printers that boasted any type of safety features.

The Da Vinci 1.0 by XYZ Printing is a low cost 3D printer, which according to the specifications offers ‘safety features’ but no-where did I find any details as to what these were. At this low price (well under $1000) I imagine safety features are very limited.

What’s funny is that the XYZ Printing website states the following:

“Enclosed for safety, but not fully enclosed”

The reason I found this amusing is because of the patent I mentioned earlier which Stratasys owns, forbidding other manufacturers from selling fully enclosed 3D printers. I guess that without those last few words they might have a patent war on their hands.

There’s also a 3D printer called the DeeGreen, which I’d not heard of either. This is enclosed too (partly I imagine), with access doors very much like on your microwave oven, which pause the printer if opened.

I’m sure more research would have turned up a few more desktop 3D printers with ‘safety features’ but the point is, they are obviously very limited.

Conclusion

It seems that with the potential risks and lack of safety features in desktop 3D printers today, if you want to be 3D printing safely with a consumer level desktop 3D printer then it’s largely down to you to make that happen.

Safety Starts With MeHopefully this will change in the near future, if consumers and authorities demand more safety features from manufacturers.

For now your best option is to be well informed of the risks involved in 3D printing and to enforce your own rules on how to print as safely as possible.

I hope this article has helped you do that. 3D printing is great fun, extremely useful and one day it might even transform the world we live in. I don’t want to scare you with this article.

The intention is purely to keep you informed about important aspects of 3D printing which the manufactures are failing to address.

I’d encourage anyone to Begin 3D Printing and encouraging beginners is one of the main reasons I do what I do. It’s also why I wrote this FREE Beginners Guide to 3D Printing at Home eBook which you can download now if you like.

Thanks for reading this article and if you found it interesting please feel free to Like it, Share it and leave a Comment. Your support is very much appreciated.

Happy 3D printing.

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{ 7 comments… read them below or add one }

Geraldo Aguiar March 17, 2015 at 1:00 pm

Excellent…

Reply

John Powell March 17, 2015 at 2:11 pm

Great article. Lots of good safety tips.
The fumes from ABS don’t seem to have a threshold limit mentioned.
As far as venting the printer the rate of airflow might be a critical factor in a good print without warping. I use the R2x and just opening the door at a critical point in a print can leave a visible line and occasionally cause a crack in a print. ABS likes a stable environment to prevent the warping so size your evacuation unit accordingly..low flow.

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David Huntley March 17, 2015 at 2:57 pm

Great article!

Suggest you formulate a type of 10 Commandments for erstwhile 3D printing enthusiasts;
e.g. 1/Check your machine purchase for Safety features
2/ Ensure your proposed work area is well ventilated & free of flammable materials
3/ Clean extruder heads with care.
etc etc

Reply

Pat McDonald March 17, 2015 at 6:48 pm

While I agree with some of the article as regards ABS fumes, there are a number of safety features built into RAMPS, the board that the majority of Reprap 3D “home made” printers use.

1) Polyfuses – bed heater and nozzle heaters have a separate polyfuse. When the current goes over the fuse limit, the fuse shuts down until the whole unit is turned off and on again.

2) Thermocouple failure – most nozzles use thermistors, rather than thermocouples. These will fail above 300 C maximum, some are only rated at 250 C. When firmware detects a short or open circuit heat sensor (thermistor) then it shuts down, displaying either a “Mintemp” or “Maxtemp” error message, and will not supply current to heaters until the thermistor is working again. It’s actually more of an issue when a heat sensor (either type) falls out of the nozzle but is still connected – then the heater will keep heating but the thermocouple will register a much lower temperature than is really present. 2 safety features have been introduced, one is a connection failure within Marlin firmware, the other is a simple screw to make sure the heat sensor stays in the nozzle.

3) Toxic adhesion layer – printing on hot Kapton tape will keep ABS sticking, printing on masking tape will keep PLA sticking. While there are benefits of using toxic substances like PVC pipe cement, as these are based on thixotropic solvents rather than trichloromethane or worse, trichloroethane, they are safer than say 10 years ago, when trichloroethane was commonly used in household products and causing cancer left right and center.

There are dangers with 3D printers, but not all 3D printers are equally dangerous.

One final point – time limitation for patents is 20 years, only in exceptional cases are extensions granted. So from a patent registered in 2000, this will expire in 2020, not as you say in 2035.

Reply

Jason King March 17, 2015 at 7:41 pm

Thanks Pat for your in depth reply. I’ve just corrected the patent expiry error. I guess I meant 20 years or so from the patent registration date but you’re right, it didn’t read that way. I’m pleased to hear that most RepRaps will have a few safety features, especially to prevent nozzle heater temperature runaway. Thanks again and I appreciate your time and your comments.

Regards,
Jason.

Reply

Print Aholicic November 15, 2016 at 9:27 am

***EXTREME 3D PRINT HEALTH ALERT***
I was in my basement with no windows open while printing. I had the printer running for about 10 hrs while i was in the basement. Throughout the day my head started feeling loopy, and my throat starting hurting when swallowing. I stopped printing and went to bed, when i woke up the next day i could taste blood. I then stumbled to the washroom and vomitted blood. Printing PLA at 215*C and bed 50*C with glue stick on heat bed.
Any tips why this may have happened, is it normal reaction to first time printing PLA,

Thanks
Dr. Bennet Omahalu

Reply

stopfire10321 March 10, 2017 at 10:47 am

The possibility of 3D printer catching fire usually DOES NOT depend on a particular manufacturer of printer, because most manufacturers are using the similar parts. Instead, the possibility of fire usually depends on the version of firmware that is installed ! More recent firmwares are more advanced and have the additional protection measures – like against a thermistor coming off place. For example, below you can find a commit message 43c298a (dated Jun 30 2014) from a Marlin Firmware repository. My cheap Chinese 3D printer (with Atmega 1284P) had a slightly older firmware version installed, so I had to update its’ firmware to enable this “Thermal Runaway Protection”! Always update a firmware of your 3D printer!!!

/*================== Thermal Runaway Protection ==============================
This is a feature to protect your printer from burn up in flames if it has a thermistor coming off place (this happened to a friend of mine recently and motivated me writing this feature).

The issue: If a thermistor come off, it will read a lower temperature than actual. The system will turn the heater on forever, burning up the filament and anything else around.

After the temperature reaches the target for the first time, this feature will start measuring for how long the current temperature stays below the target
minus _HYSTERESIS (set_temperature – THERMAL_RUNAWAY_PROTECTION_HYSTERESIS).

If it stays longer than _PERIOD, it means the thermistor temperature cannot catch up with the target, so something *may be* wrong. Then, to be on the safe side, the system will he halt.

Bear in mind the count down will just start AFTER the first time the thermistor temperature is over the target, so you will have no problem if your extruder heater takes 2 minutes to hit the target on heating.*/

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