Need some 3D printing help for COVID-19

August 11, 2020

Need some 3D printing help for COVID-19

Mid 2021 update: High thread count cotton and/or multi-layer polyester satin isn't a good choice for high filtration masks. They're not breathable enough at mid filtration performance. And additional layering to get to hight filtration still only decreases breathability further. With that they get hot and uncomfortable as well as giving your chest muscles a good workout.

This blog post is in respect of the high-filtration washable cloth mask I make on my sewing machine.

Link: https://fu-cv.blogspot.com/2020/08/3d-washable-750-thread-count-cotton-and.html

3D Design work needed

I make a "retainer" from IKEA SNOBBIG placemats. It clips into high-filtration (very high thread count cotton + satin) masks. It stops the fabric pulling onto your nostrils lips as you breathe in - solving the breathability problem for such designs.

SNOBBIG like most of these placemats are PVC. That's easy to cut, but it smells a little inside a mask. It has to be taken out for washing too, as it gets crushed and loses strength if you don't.

Ideally, there could be something 3D printed flat and inserted into a mask under curved tension (ideal). The mesh doesn't have to be as fine as it is for SNOBBIG. Shouldn't, in fact. No smell (food safe?) yet bendable with some tension and longevity are key.

The washable cloth mask it would go into, if you're interested: LINK. I've been iterating cloth mask designs with retainers/stiffeners for breathability since early March.

Crappy SVG I made

(actual SVG)

Another design that doesn't so much bend in the middle, but instead is two mirror-image plastic 3D prints, with a metal clip to join them (and pivot around at the central seam):

3D printed hinge variant:

Buddy Zack's AutoCAD/DXF work:

History

I've been mucking around with the "RagMask" design for months now. Here is the last time I was trying removable retainers EXPERIMENTING WITH RETAINERS - THAT FORCE MASK CUPPING FOR INCREASED BREATHABILITY (Apr 26th, 2020). That was for 400-tc cotton, and for 750-tc cotton the retainer needs to be much larger as the fabric really pulls in as you breathe in. Much larger and properly designed.

Please get in touch with me - paul@hammant.org - if you want to get involved (open source, non commercial)

Sept 6th edit: Attempt to make a more solid PVC retainer

Reverting to the PVC placemats from m local supermarket ($2 each; PIC), and a craft knife & slide guillotine:

Verdict: stiffer (good) but 30% less breathable (bad). I might try again with a hole-punch ($4) or belt hole punch ($9) and a more packed formation of holes in order to boost breathability Note: laser-cutting PVC comes with a risk of releasing hydrochloric acid which is an extreme irritant to some.

Sept 9th edit: Second attempt to make a more solid PVC retainer

One side:

Other side:

Verdict: Much more breathable, but harder to make as there's only so far the $4 Amazon single-hole paper punch can reach, and I've finished it with a craft knife (at some risk to my fingers)

Sept 22nd Edit: yet one more:

My pal Lesley showed a laser cut design for a retainer that feature V cuts in the outer circumference allowing them to adopt a more 3D shape when pushed into the mask. I thought I'd try that with my non-laser cut retainer.