I recently bought a small vacuum pump for a project (I will get into that at a later date) and found it to be surprisingly noisy. At first I thought the noise was emanating from the housing itself, but when I blocked the outlet port with a finger the noise was cut down dramatically. A colleague suggested a muffler (thanks Keith!) and another gave me some tips on how they work (thanks Andy!) so I set out to make one.

It turns out there are several strategies for muffler design, and some of them get complicated, acoustically speaking. Most engine mufflers are optimized for unrestricted air flow, as air resistance saps horsepower. In my case the air flow is relatively low and I’m not concerned about a fractional drop in suction, so I went with a simple maze-like muffler design, intended to disperse and diminish sound pressure as the waves travel through the maze.

I printed the parts on the FDM machine…

then glued the two halves together. Is there anything Loctite can’t do?

The inlet port is sized for my 1/4″ ID hose, although in a future iteration I would add a barb feature to make the attachment a little more positive. For now I’ll just use a small hose clamp.

I measured the sound level (from 18″ away) at about 93 dB without the muffler, then about 82 dB with it. Hear for yourself:

http://www.youtube.com/watch?v=vr3N5bwage4&width=600&height=337

