Gas station without pumps

2020 April 4

3D-printed nose clip for fabric masks

Filed under: Uncategorized — gasstationwithoutpumps @ 14:34
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I saw that Prusa had released a couple of designs for nose clips for closing the gap in fabric face masks that causes glasses to fog up. They call it “Face Mask Pozicer”, which I think translates from Czech as “face-mask positioner”.  (Incidentally, this public-service announcement from Czechia is well worth watching.)

I tried printing the positioners today, but they were too fragile in PLA (Prusa had used PET,which is a better material for this application), did not fit my face well (too wide, so there was still a gap), and had clips that had too little clearance for the fabric mask I made. They did not provide a model that I could edit easily, so I tried my hand at designing my own, based on their design.

I first tried scanning the print from the design of their that came closest to fitting, cleaning up the scan with gimp, and doing a trace of the bitmap with inkscape.  This process took a long time and ended up with a rather sloppy-looking 2D version of their design that was still not easily edited.

I then used the cursor in inkscape to pick out about 9 points along the curve of one side of the nose piece and used OpenSCAD to symmetrize the list of points, make a smooth Beziér curve from them, and add the clips. I ended up tweaking the points to get a shape close to the longer, thinner model from Prusa, but a little thinner still. I did some of the tweaking by holding the printed model up to the screen with the rendering sized to be life-size.

I made all the parts be 2mm thick, instead of only 1mm, and increased the gap for the fabric from 1mm to 2mm. Because the file is all parameterized, I can pretty easily tweak the design if the first version doesn’t work.

Well, the first version did not work—the clips were too stiff and had too small an opening, so one of them broke while I was trying to get the nose piece onto my mask.  I redesigned with a fillet to strengthen the part that broke, 1.5mm thickness rather than 2mm, and more clearance for the fabric.  That clip seemed to work fine.

The clip does a good job of holding the mask down to the nose, avoiding the gap that fogs glasses.

The glasses can even fit over the clip a little.

Here are the three models: first Prusa’s longer-thinner model, then the beefy one with 2mm walls, then the final design with 1.5mm walls. Note the broken right-hand clip on the beefy model.

A closeup of the clip in version 3. Note the fillet at the bottom and the rounded thick part at the top.

A 3/4 side view of the clip without fabric.

The clip view from the inside of the mask.

I’m now going to make a more cheerful mask using some blue ikat fabric, and see whether the clip fits on that mask also. If so, I’ll print another one, so that I can have a spare.

I have uploaded the design to Thingiverse: https://www.thingiverse.com/thing:4261629

3 Comments »

  1. […] cheerful fabric and made the ties out of the same fabric as the body of the mask. I also used one of my 3D-printed nose clips to close the gap that would otherwise fog my […]

    Pingback by COVID-19 mask #2 | Gas station without pumps — 2020 April 5 @ 15:05 | Reply

  2. […] to the ones I made (here and here), but with a wire to shape the mask to the nose, rather than a 3D-printed clip like I switched to and with 4 layers rather than 2 […]

    Pingback by Local effort to produce PPE | Gas station without pumps — 2020 April 6 @ 11:06 | Reply

  3. […] posted earlier about the nose clip I designed to keep my cloth masks from fogging up my glasses, based on the design from Prusa.  The nose clip was not as good a fit […]

    Pingback by Improved 3D-printed nose clip for fabric masks | Gas station without pumps — 2020 April 30 @ 16:54 | Reply


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