These are tough and confusing times.
COVID-19 has caused a huge shift in everyone's lives and we are all battling it and trying to help out in any way we can.
One day my wife had come home from working at a hospital and had told me that they had run out of masks in the pediatric section of the hospital and therefore weren't able to wear any PPE. We both wanted to help in anyway that we could, so we started researching ways to help. We came across a dentist who had designed a 3D printable mask that contains a way to change out the filter portion of the mask. That's when we decided we were going to start printing as many masks as possible to help whoever needed them.
Filter Shell
We started by printing out a prototype of the dentists design, adding in a cutout of our filter sheet (described later), and hot gluing some unattractive, thin rope that we had lying around the house to allow for the mask to be worn.
The original design for the filter masks can be found here:
We quickly recognized that although the mask fit my face well, it did not fit tightly on my wife's face. We decided to try scaling the entire model down by 10% and reprinted the design and that worked perfectly to fit my wife's face. That's how we ended up having our "large" and "medium" sizes that we have been providing for these masks.
3D Printers Used to Develop these Masks
We started off printing these masks with my Anet A8 3D printer, which was my starter printer that I purchase about 3 and a half years ago. This is definitely an introductory printer with a lot of gimmicks and issues that come with it. I've actually enjoyed owning this printer, because it's allowed for me to gain an in-depth knowledge for all the pieces and intricacies that are involved with 3D printers. However, this knowledge is gained through it constantly breaking down and the need to take it apart to fix all the different issues. It was doing fine creating these masks and we were able to print up to 6 a day, but we also wanted to step up our production to really help make a difference. We decided to purchase a Creality Ender 3 Pro to help with this. This is another low-end 3D printer, but it is actually a huge step up from the Anet A8 in it's repeatability and it definitely doesn't break down as often (at least not yet). With these two running full steam ahead, we are able to print around 12 masks a day!
Testing Out if the Mask Fits
With recognizing we needed to have two different sizes for our own faces, we also realized that it was important for everyone we sent these masks to to know how to ensure the mask was a tight fit for them as well. The reason for this is that even though COVID-19 particles are airborne, they do fall to to the ground over time. So, if you came in contact with the particles and had a mask that wasn't tight fitting, it's actually a higher risk for the particles falling through the top of the mask and then being trapped inside the mask against your face. In these scenarios, they actually say that it would have been better to just not have worn a mask at all!
With that, 3M provides several tests for ensuring the effectiveness of masks, as well as some tests that you can conduct on your own to ensure it's a tight fit. The most simple of these checks are to just cover the filter section and breathe out and breathe in. When breathing out, you should feel air escape and you should feel it fill with pressure. When breathing in, no air should come in and the mask should pull to your face. More details on these tests can be found here:
https://www.3m.com/3M/en_US/safety-centers-of-expertise-us/respiratory-protection/fit-testing/
Elastic Cord and Tightener
To help in ensuring there is a tight fit, we chose to provide an elastic cord with each of the masks, as well as a cord tightener. We started off with the following two products that we were able to purchase from amazon:
However, this quickly sold out through their website and the price of the single barrel spring cord locks was significant enough to make us consider looking for an alternative. We decided to create a simple design within Fusion 360 of curved oval that fit comfortable on the back of a person's head or neck, and that had 4 holes that were a little bigger than the size of the elastic cord being used. Routing the cord through these four holes easily allowed for tightening and loosening the mask, and we would be able to print these pieces right alongside all of the masks! The file for this design is here:
The Filter
For the filter, we decided to use Filtrete 1900 MPR Maximum Allergen, which is just a household air filter sheet that is readily available at most local hardware stores. When trying to come up with the design for this mask, we wanted to use a filter that was more effective than the surgical mask material we saw being commonly used in most reusable filter masks, and we also wanted something more effective than the common hankerchief that has become popular as well. Looking into these Filtrete filter sheets, we found that it actually filters out particles (including viruses) down to 3 microns at a 93% rate! COVID-19 particles go down to this 3 micron size, so we expect the filter to meet the minimum requirement to be effective for this virus, and although it doesn't hit the 95% rate of effectiveness found with N95 masks, we think that these might be one of the better solutions out there. Even better is that it's a readily available product, and one of these sheets can create more than 100 different filter sheets! When doing a quick search, I was able to find that my local Lowes currently has 40 of these sheets available.
With that being said, this is all based on our own research and we aren't specialists of any kind. We are just hoping this can help get out a viable solution to those in need.
Finishing
Now that we've covered the face mask design and all of the parts that go into making the final product, let's talk about finishing! If you've ever 3D printed anything, you know that it can sometimes take a lot of finishing to get the print to the quality you want. Luckily, these masks don't need too much! We mainly need to sand off some of the initial layers of the print for both the mask and the filter sheets. Once all of the supports are gone, we then apply a food safe, water based sealer to the masks (Mod Podge). We apply 2-3 layers and then the masks are all ready to go!
Thanks as always for following along our maker journey! If you are looking to purchase a mask, we are selling some through our Etsy Shop and the costs of these are going to more material purchases for the masks being donated to the hospitals. Thanks again for reading and hope to catch you on the next project!
