April 8, 2020
Description
This is a face shield that attempts to simplify the shield of other common 3d printed masks by using a standard comb ring binder punch instead of laser cutting to allow dozens to be assembled in a few hours without highly specialized tools. The current revision has a pair of loops allowing 1/2" to 1" elastic bands cut to 13" to be fed through the holes like a belt friction fitting eliminating the need to tie the material, and allowing continuous adjustment for improved comfort. Additionally the 0.25" band version of the design accommodates the more common 0.25" elastic material. the 0.25" band is more comfortable and prints ~13% faster at ~13 grams so it is recommended for indoor environments while the 0.5" version is more suitable for the outdoors.
By eliminating the double band of other 3d printed shields we resolved the issue of the top of the shield being open to the air between the forehead and the shield without greatly increasing the print time or geometric complexity aiding in the process of cleaning and reuse of the shield. The elastic band is elevated ~1" above the plane of the print causing the shield to pitch 11 degrees away from the vertical axis creating clearance for N95 masks. Additionally the 0.25 band is for more readily available 0.25" elastic material.
This print also reduced material use and nests much better than other printed masks allowing for 4 prints simultaneously on 200^2 mm printers, 6 prints on 300^2mm printers and up to 22 on 500^2mm printers. with typical print weights of 20 grams or ~$0.40/each. Additionally the shield material is a common 8.5"x11" cover punched with a comb ring binder making it exceedingly easy for the end users, in our case Missouri EMTs, Police, Nurses and Doctors to stock and replace these items. Currently the design is approved by a half dozen EMT units in Gasconade, and Franklin County, is being used in two hospitals and by 3-4 police stations. Our small enclave of 7 printers can comfortably turn out 120 masks/day and we have provided 350 for these communities over the past 3 days with thousands to come. with a per unit cost of $0.50/each these are quick enough to print that if they are irredeemably soiled the medical technicians can discard them but are geometrically simple enough to be cleaned if possible. Local to Mid Missouri this design has some institutional approval perhaps saving precious testing time for other would be donors.
Comb Binder Punch:
https://www.walmart.com/ip/OTVIAP-21-Hole-450-Sheets-Paper-Comb-Punch-Binder-Binding-Machine-Scrapbook-Punch-Driver-Tool/663466387
License:
Creative Commons - Attribution
Benjaminonious
