3D Printed parametric 40mm gas-mask canister

Cartouche paramétrique de masque à gaz de 40mm imprimé en 3D (version francaise ici)

[English version automatically spell checked with minimum effort put into proofreading]

Here is the printable page for this model.

1 - Design and usage

⚠️ WARNING : Please don't use a 3D printed canister (or even our mask) in life threatening situations ! ⚠️

This canister is made to be used with mask supporting standard 40mm threaded canisters - sometimes also known as "nato threaded" canisters - which the standard dimensions are defined in sources/nato_thread_spec.png.

This filter canister works by holding a filtering material - usually activated charcoal - in between two securely held mask/filter pieces.

The center sleeve is made to hold both the mask/filter pieces, using the pressure of the two outer shell part being screwed in together around the sleeve.

This repository also provides a plug to use instead of a canister for masks that have two threads for canister - like the one we provide at distorsion/3D-printed-parametric-gas-mask - which you can print from the 3Dfiles/nato_thread_plug.stl file.

2 - Assembly

Once you have printed all the required pieces as described in the 3D printing section, the assembly is simply done in three steps :

You can first put your (covid/chirurgical) mask or filter and put it in the cap or at the top of the sleeve, with 0.5/1cm extra material all around the sleeve.

Secondly, you can push in the sleeve within the cap making sure that the whole surface of the mask/filter is firmly held and that there are no holes.

You can then fill the sleeve with your filter material : typically activated charcoal which can be source cheaply from activated charcoal for aquarium filter.

Finally you can repeat the first step with the top of the sleeve, putting a mask/filter, then pushing the sleeve/cap assembly into the main body before screwing the cap and main body together, thus securely holding the sleeve and he two mask/filter holding the filtering material in place.

3 - 3D printing

To assemble a full canister, you need to need to print :

• 1 sleeve from 3Dfiles/canister_sleeve.stl
• 1 cap from 3Dfiles/canister_cap.stl
• 1 main body from 3Dfiles/canister_main_body.stl

You can also print a plug to use instead of a canister for masks that have two threads for canister - like the one we provide at distorsion/3D-printed-parametric-gas-mask - which you can print from the 3Dfiles/nato_thread_plug.stl file.

There is no particular printing parameters or material requirements to make this canister properly work. Note that every file provided can be printed without support :

• print the plug (3Dfiles/nato_thread_plug.stl) with the flat face facing down.
• print the sleeve with one of the open end pointing down.
• print the cap with the flat face pointing down.
• print the main body with the 40mm thread pointing down, you can add a skirt to support it better if you fear it falling over mid-print.

4 - Parameters

If you want to changes the parameters of this design, you can edit the Freecad file 3Dfiles/40mm_gas_mask_canister.FCStd, which is fully parametric, with parameters present in the Spreadsheet.

If you want/need to change parameters, we would suggest you play with them and try to understand the impact of each parameters. We will only explain a small selection of important parameters that you are most likely to have to edit.

We will only describe a few parameters that you are most likely to have to change.

4.a - Structural parameters

wall_thickness : [default=2.7mm] The wall thickness across the print (except for the strap attachment point). Can be tweaked to make the print either stronger or weaker but lighter and faster to print.

snap_fit_clearance : [default=0.09mm] The clearance between two objects that would fit together with difficulty. Also impact the clearance between threads.

4.b - Geometrical parameters

The two most important parameters that you would probably have to tweak for your usage are :

filter_diameter : [default=55mm] interior diameter of the filter, the larger the diameter the easier breathing will be, but also the better filtering will be as air will pass more slowly through the filter for the same air flow, thus making the filter more effective. A larger filter will be heavier and thus be less comfortable.

filter_length : [default=35mm] interior length of the filter, the longer the filter will be, the better the filter will work but also the harder it will be to breath. A longer filter will be heavier and thus be less comfortable.

License

"3D Printed parametric 40mm gas-mask canister" (c) by @distorsion

"3D Printed parametric 40mm gas-mask canister" is licensed under a
Creative Commons Attribution 4.0 International License.

You should have received a copy of the license along with this
work. If not, see <https://creativecommons.org/licenses/by/4.0/>.