software tech

Fu Mask Cutting Templates

An area sanatorium contacted Mary’s quilting workforce to stitch up material covers to extend the existence in their medical-grade N95 mask. Their advisable trend, the Fu Face Mask from the FreeSewing workforce, is available in three sizes:

Freesewing - Fu MaskFreesewing – Fu Mask

N.B.: Use their authentic PDF, as a result of a JPG image more than likely received’t pop out on the proper dimension.

Also N.B.: Used on its own, this isn’t a medical-grade clear out masks.

The patterns don’t come with the standard 1/4 inch seam allowance across the outdoor, so I cranked out plastic chopping templates.

The plan of assault:

  • Convert masks outlines right into a bitmap symbol (GIMP)
  • Create Bezier curves by way of tracing outlines (Inkscape)
  • Save curves as SVG information
  • Convert SVG into forged style (OpenSCAD)
  • Add stiffening ribs &c
  • Save as STL forged style
  • Slice into G-Code document (Slic3r)
  • Fire the M2!

So, we start …

Import the PDF into The GIMP, delete the textual content & suchlike, convert to monochrome, and save the trend outlines as a PNG document:

Fu Facemask - outlinesFu Facemask – outlines

It seems Inkscape can immediately import the PDF, but it surely valiantly tries to transform the entire textual content and the incidental graphic parts, none of which might be helpful on this state of affairs. It’s more uncomplicated to delete them in The GIMP and make a financial institution shot off a PNG document.

Import the PNG into Inkscape and hint one define with the Bezier curve software:

Fu Mask - Inkscape Bezier traceFu Mask – Inkscape Bezier hint

If you squint actually sparsely, you’ll see Bezier keep watch over handles protruding of the nodes. I laid three nodes alongside the highest arc and four alongside the precise facet, however do what’cha like; the Insert key or Shift+I inserts and Delete gets rid of nodes. It’s more uncomplicated to heart a node in the midst of the PNG line with snapping grew to become off: Shift+drag whilst mousing or globally with #.

You may just unharness the bitmap auto-tracer, but it surely generates a bazillion uselessly tiny Bezier curves.

When you’re glad, choose and replica the trail with Ctrl+C, paste it into a sparkly new Inkscape report (Ctrl+N) with Ctrl-V, put it aside with a catchy document identify like Fu Mask - Small - nominal.svg, and shut that report to go back to the report with the PNG outlines and the unique trail.

Select the unique trail once more, create a dynamic offset with Ctrl+J, open the XML editor with Ctrl+Shift+X (which automagically selects the right kind SVG part), and alter the inkscape:radius price from 0 to 6.35 (mm, which everybody will have to use) to get a 1/4 inch seam allowance:

Fu Mask - Inkscape XML Editor - Offset radiusFu Mask – Inkscape XML Editor – Offset radius

The trail will puff out with curved corners:

Fu Mask - Inkscape offsetFu Mask – Inkscape offset

Copy into a brand new report, save as Fu Mask - Small - seam allowance.svg, and shut.

Repeat that procedure for every of the three masks sizes to create three pairs of SVG information: the nominal masks define and the corresponding seam allowance define for every dimension.

The OpenSCAD program imports the SVG information, gets rid of the nominal define from inside the seam allowance to depart the description, provides stiffening ribs, and stamps an ID letter on either side of the central button:

Fu Mask Cutting Template - Small - solid modelFu Mask Cutting Template – Small – forged style

Choose one of the three sizes with the OpenSCAD customizer, save the ensuing style as an STL document, repeat for the three sizes, and also you’re accomplished.

This procedure can convert any define paths in SVG information into chopping templates, so, will have to the Fu Mask no longer fit your fancy, Use The Source.

For comfort, the STL information are on Thingiverse.

The OpenSCAD supply code as a GitHub Gist:

Verily, there’s not anything like a excellent new downside to take your thoughts off all of your previous issues …