Air line muffler for 1/4" NPT

Pneumatic muffler which reduces exhaust noise on air lines by using dense infill. Adjustable for performance by changing infill settings.

Has wrench flats but does not need to be installed very tight, it's recommended to just hand tighten, and pipe compound or PTFE tape is not necessary, the plastic itself will function to seal the threads well enough. Plus, you're not holding pressure, you're just restricting it to kill the exhaust noise.

Available in two sizes, both 25mm outer diameter and either 25mm long or 50mm long. The 50mm long will have more surface area so should likely provide less restriction for a certain noise level attenuation, but all of my testing was with the 25mm version.

Can be customized to your preferred performance by adjusting infill. Works best with Rectilinear or Lines infill, but can work with Gyroid, Cross Hatch or Honeycomb, but those take more time to print and I don't think that they really increase the performance of the muffler, but I haven't tested extensively.

Do not use infill such as “grid” or “cubic” where it creates a “watertight” infill as the idea is to allow the air through, but restrict it. With those infills, you'll probably just cause the piece to blow apart at which point it won't accomplish anything.

Requires a bit of preparation in the slicer to function, so make sure you read the printing instructions.

Printing instructions

I've got two 3MF files set up for both PrusaSlicer and OrcaSlicer with these parts loaded and the following settings defined.

The key to printing this is understanding that there are two bodies which have to be printed differently. Looking at the cross sectional photo, the “head” (pink cross section) is to be printed solid, with shells, and the “mesh” (yellow cross section) is to be printed with no shells and a dense but not watertight infill.

The easiest approach is to load up one of the “complete" files which contains both bodies. Otherwise, you can download the individual “head” and “mesh” bodies, but that just makes more work, and if you're using a slicer that can't handle the “complete” 3MF files, really consider upgrading to something modern.

Once you've got the bodies loaded under one part, you can set the default print settings. I start with a 0.2mm layer height for my printers with 0.4mm nozzles, and set that to 3 shells. Then, I click on the “mesh” body and add infill and perimeters customization. My recommendation is this:

• Shells: 0
• Top solid layers: 0
• Bottom solid layers: 0 (or 1 to promote bed adhesion if you have issues with that)
• Infill: 80%
• Infill pattern: Rectilinear

You can adjust the infill percentage to adjust the performance. Higher infill will restrict flow more, and reduce the exhaust noise.

Material choice is up to you. I use PETG with good results but as long as the exhaust air isn't hot, PLA can probably work as well. Higher temp filaments can be used in hotter environments. Feel free to experiment.