<peepsalot>
any ideas for a check valve design with low cracking pressure? basically something you could easily exhale through
<peepsalot>
i made something with a ping pong ball in a printed funnel shape that would rest on an o-ring under gravity, but apparently getting my 3d printer is not able to make a perfectly round enough hole for the ball to seat on the ring with no backflow
<peepsalot>
i'm trying to do something with basic PLA and o-ring or other common hardware if possible
<J23k>
but yes you would need something flexible for it
<J23k>
what can be done with PLA and if you print on glas (smooth surface) is a
<J23k>
reed valve so a thin layer of PLA is bend open
<J23k>
or just a disc with a cage as the mating surface is flat (from the glas print bed) you can ignore tolerances from the printing
<Scopeuk>
peepsalot how good of a seal do you need, if significantly 1 way rather than a shutoff value a https://en.wikipedia.org/wiki/Tesla_valve is quite printable
<peepsalot>
i would like a pretty good seal that air cannot diffuse back in. i need to sample a volume of air with some sensors that have ~30s response time. so i don't want any significant ambient air to backflow during reading
<J23k>
the o-ring would be in the disc and pressed against the flat surface
<peepsalot>
if the disc is printed, the o-ring channel will not be flat because the channel has a start and end. would require significant pressure to keep seal with o-ring. i think o-ring is proabbly a bad idea in general for this particular usage
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<peepsalot>
seems that just sanding the funnel down makes much better seal than trying to rely on nitrile o-ring. I put a little patch of sandpaper on the ball and spun the funnel around on it to shape it a bit
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