Compressor vent / drain muffler 1/4'' coupler - with baffles

The original model helped, but it will still quite loud, so I added a bowl at the end of the “inlet” tube a few baffles to further reduce volume. It seems to have made a significant difference.

The cutaway is for demonstration only. The sound samples were taken with a phone, so I cannot guarantee accuracy, but the volume of the compressor running (~60dB; after the venting peaks) matches the noise level listed on the compressor, so it seems to be fairly accurate. 

I printed mine with a flexible PLA midsection with the assumption that a softer material would absorb some sound energy; this has proven true. I also varied infill from 10% to about 30% at the exit to prevent direct exit paths and further reduce noise, but I did this on the original as well. 

Including a flex section in the middle seems to make a significant difference. I printed my model with regular PLA, and it was nearly as loud as the original. I printed only the middle in flex for two reasons: I found the flexible PLA I have sticks to the print bed too well, so one or more layers of regular PLA help removal, and I also think the coupler/plug end should not be flexible.  

I don't normally bother including anything other than the STL, but since I set so many height range modifiers, I figured I'd save people the hassle. The model also requires height range modifiers to correctly slice the baffles but not create blockages within the model. If you slice it yourself, check the sliced layers to make sure it looks right; it should have baffles, but no other obstructions. 

The original model helped, but it was still quite loud, so I added a few baffles to further reduce volume.