40MM NATO (RD40x1/7) to Scott® 742 Series (Bayonet) Filter Adapter

thingiverse

This prototype design enables a seamless transition between the 40MM NATO (RD40x1/7”) gas mask thread and the Scott® 742 series filter adapter, making any RD40x1/7 threaded full face CBRN masks compatible with the Scott® 742 bayonet series line of chemical, combination, and particle filter cartridges. This solution helps mitigate PPE shortages by expanding cross compatibility of respirators and filters to other manufacturer models. Part Description: The design is represented in the 40MM_NATO_TO_SCOTT_742_FILTER_ADAPTER_GEN1.stl file, which is the initial model release. Disclaimers/Risks: 1.) Use Proper Gaskets Use OEM gasket under bayonet or similar nominal OD of 28.5 mm to ensure a secure seal. 2.) Perform Proper Negative Pressure Test Put on your respirator, adjust straps until they are taught against your face, and make sure there are no obstructions around the periphery of the seal against your face. Exhale deeply, cover all inhalation ports with your hands, and then inhale deeply. The mask should suck tightly against your face without any air leakages. Re-test if adjustments are required at gasket/o-ring interfaces at the adapter. 3.) Use At Own Risk – Temporarily Solution Only Until Supply Chain Normalizes Due to the limitations of 3D printing materials, this adapter is only a temporarily ad-hoc solution against biological contagions. To increase durability and resiliency, it is recommended that users apply a thin layer of polyurethane clear coat on all exterior surfaces. Dev. Notes: The initial model release was made on 5/08/2020, and the design is still in work pending support from the 3D printing community for any fitment and model revisions. Credits: Thanks to tobias1pl for providing the Scott® 742 adapter for DIY cotton pads design. Their images and dimensions were used to extrapolate the bayonet side attachment geometry. https://www.thingiverse.com/thing:4334140