MP-5 Respirator Strap Extension (parametric)

thingiverse

Parametric OpenSCAD design for headstrap extension clips of this respirator: [Polish military respirator model MP-5](https://gasmaskandrespirator.fandom.com/wiki/MP-5) This design allows to create extensions for the middle and upper headstrap mounts, removing pressure from the straps if your head is too large to wear the mask comfortably with the original straps. In Europe, surplus stocks of the Polish MP-5 respirator is widely available on eBay etc. in like-new quality for about 20 EUR. It is a relatively recent (2006) model and I can't see any way how it would be worse than new masks that you can buy for 200 EUR and up. So for people looking for affordable high-grade protection during the coronavirus pandemic, this together with a P3 R filter with RD40 mount is a good option. Still, I don't expect that the design will be used by more than three people total for its original purpose :P You can however also use it to learn some new OpenSCAD techniques, as I figured out some interesting OpenSCAD code organization techniques for parametric designs here. ### Usage and assembly 1. To use this design in OpenSCAD, you also need to install the Round Anything library: [Round Anything library](https://github.com/Irev-Dev/Round-Anything/) 2. Customize the part in the OpenSCAD customizer by choosing the extension length. (It does not work in the Thingiverse customizer, as Thingiverse cannot process include() statements.) 3. Print the upper part and lower part twice each. I used ABS with 100% infill. 4. Remove the original middle or upper headstraps. The design does not work for extending the lower headstraps. 5. Remove the triangular clip around the mask's attachment point for the headstrap. 6. Hook the lower extension part with its slot around the mask's attachment point. 7. Insert the part that remains on the end of the headstrap into the other end of the extension part. 8. Press on the upper part of the extension and seal the parts together with a usual 4.8 mm wide cable tie, using the groove prepared for that.