Cap for Co2 bottle with thread W21.8x1/14

thingiverse

I was looking to find a cap that would fit my Co2 canisters of 500gr and 2kg but couldn't find anything. The purpose of the cap is to keep dust out when storing bottles. There is room for a rubber grommet at the bottom but read the caution below before adding such a grommet. After experimenting with custom threads in Fusion 360, I have taken the maximum tolerance allowed for internal threads and rounded the threads in Fusion 360 as it was still very tight with the max tolerance per DIN477 DANGER ! A caution is to be made: this cap could become a projectile or a fragmentation grenade if you open the bottle and the cap is screwed on the bottle. If you want to play safe, only put a cap on completely empty bottles. Plastic will likely not withstand 60 bar of pressure which is the pressure of a co2 container at room temperature. I didn't test it but I'm pretty convinced it will crack or blow apart. I don't take any responsibility whatsoever for any mishap caused by using this design. Can't say I didn't warn you !