Are 3D Printers Safe?
This is a large and sometimes contentious topic. Let's separate the discussion into 4 areas: The printer's heaters, pinch zones, and the material being printed.
The Printer and it's heaters - Any electrical device with heating elements and moving parts will always require some extra attention. The most frequent question that I'm asked is whether a printer is safe to be left alone. I believe printers such as the Ender 3 can be left alone to some degree. By this I mean, in a school I would not leave a printer printing overnight. I would also physically have the printer located in a area where no material can fall on the printer or if anything goes very wrong with the printer that it can't touch other combustible materials. This being said newer versions of this printer are capable of thermal-run-a-way protection. This feature will shut off the printer in case it senses excessive temperatures or if it fails to get a proper temperature reading.
The Printer and it's Pinch Zones - When educating others on printer safety you should stress that there are several areas where hands and fingers can get caught. Some printers have complete enclosures that project the printer and the user. Part of learning to print on a 3D printer is learning how to use it safety. This similar to using any other electrical tool.
The Filament - Recently there has been a lot of chatter on this aspect of 3D printing in schools, and other smaller spaces with minimal air exchanging. Firstly, I would highly recommend that you begin with printing PLA before you attempt any other materials. Discussion on PLA to follow below :-). PLA is an excellent filament with many general uses. It's reasonable strong, easy to print, can be printed at reasonable low temperature, and as a bonus it's actually bio-degradable. Other filaments bring a variety of printing "issues" whether they be safety or just difficulty in getting a successful print.
Micro-particles - Most manufacturing processes produce micro-particles that we can breathe in while we are working in a manufacturing environment. 3D printing is no different. However, while printing PLA, at what would be considered normal temperatures, the amount is very small. There are an number of studies that have shown the biggest issue happens during the printing of ABS. In my opinion ABS should only be printed in a outside vented enclosure. This is something I will investigate later.
Let's take a closer look at the safety issues with Printing PLA (polylactic acid). Of the printing materials you could use this is certainly the best! There has been some discussion on how safe is PLA in terms of the gases it might produce during the printing process.
I decided to do my own "non-scientific" investigation into printing with PLA. I borrowed a photoionization detector (PID). This particular model was a Honeywell BW Ultra. This instrument can detect several gases. However I was only looking for any VOCs (volatile organic compounds). These are the ones that are often noting in printing in other materials such as ABS. The particular meter I used will go into alarm at 50 ppm. (parts per million). Keep in mind this meter does not identify which VOCs are present but rather that they are present. There is a huge amount of information available on VOCs and their affect on human health. My goal was simply to see if any VOCs are produced during printing and in what concentration.
I started with my Ender 3 printer at home. It's located in a room approximately 100 sq. ft. For this exercise I kept the room without any form of ventilation and I took reading several times along a 2 hour print. I used, what could be considered, regular PLA. (no noted additives such as wood, carbon fibre, etc.) I printed at 205C degrees on the nozzle and 65C degrees on the bed. Truthfully I was expecting that the meter would register some VOCs but in a very low concentration. However, no time during the my "non scientific" test did I get anything other than 0 ppm. I had a certified industrial hygienist look at what I was doing and he noted how the test was performed was indeed a good way to get a VOC reading. I placed the meter about 30 cm from the head of the printer and took readings at various times including warm-up and printing. At no time in the process did the meter detect anything different from the reading you can see in picture. I repeated my "experiment" 2 more times with 2 other printers. The results were the same. Incidentally, the hygienist suggested I try the meter on a dry erase marker. I placed it within about 10 cms of the meter and the meter immediately went into alarm reaching over 100ppm. A permanent marker registered over 200ppm in a similar test.
In conclusion, I was simply looking to see if printing PLA at normal temperatures produced any volatile organic compounds. I did not detect any! So for "ME" I feel safe in using my 3D printer at home in terms of emitted VOCs. I also feel comfortable in printing PLA at "normal" temperatures in a classroom situation. Other safety concerns of 3D printing such as; physical injury, particulate production, and printer failure are certainly a different topics and should be taken in account when 3D printing.