Air Rifle Suppressor - for felt/foam

Air rifle moderator, for use with sound dampening felt or foam. 193mm overall length, the tube is 185mm long, 40mm outer diameter, 36mm inner diameter, each cap extends 4mm out of the tube. Inspired by the many aftermarket designs that use some variation of hair curlers and sound deadening felt material instead of baffles, and the many 3d printed designs out there that people won't share the files for.

Why this over traditional baffles? It seems to depend on the individual airgun (or "pellet gun") which kind works better. On a couple of air rifles (.177 PCP - Air Arms S200 (CZ 200) and a .177 break barrel - Remington Express) I found this sounds quieter than a silencer using baffles and the same overall length. I'm tempted to design a two stage suppressor that uses both, and test that, maybe get the benefits of both?

If you have any tubing lying around with an internal diameter of 36mm, that would be perfect for this when cut to 185mm. I didn't, so printed the tube as well (40mm wide, 2mm thick, 36mm inner diameter, 185mm long). Printing horizontally for increased strength meant the tube experienced a little shrinkage (9% horizontally, 1% vertically), so I made a bigger model (Tube_40mm_account_for_shrinkage.stl) that accounted for this shrinkage, which worked perfectly.

Regarding material to wrap the inner tube after the mesh wrap - any kind of sound dampening material should work. Cheap 3mm felt, acoustic foam, old thick socks. There's a lot written about it elsewhere, I suspect you'd get reasonable results with any kind of soft fabric.

Threaded for 1/2 20 UNF, the standard for most airguns.

Assembly

• Wrap the inner tube tightly with the mesh and tie or tape it in place. Tightly wrap sound deadening material around this, again secure it in place.
• Insert this into either of the end caps, is a tight fit so use some force if needed.
• Insert this into the outer tube, perhaps use some superglue.

Insert the remaining end cap into the other end, again maybe with some superglue. Apply pressure to both ends to tighten the inner tube with both end caps. Should be very tight and difficult to pull apart. #### Notes

Because of the way I've designed the inner tube and end caps, it is a very secure fit. I didn't need to use any glue to hold it together.

Two end cap files included, one with 6mm hole and one with 8mm. If you have a calibre greater than .22, use the 8mm file. In addition, if you're worried about a pellet's path not being straight after printing, which is reasonable enough, use the 8mm file.

The hole in the inner tube is 8mm wide.

Instead of printing the mesh to wrap around the inner tube, if you have any stainless steel coffee filter mesh or a fan filter you could use that if you cut it to size (147.5mm x 75mm). Something like mosquito net would probably work too. The point of the mesh is to stop hairs from the material entering the main tube and coming out of the end when firing, or otherwise getting in the path of the projectile.

Total volume inside the tube with both end caps is 150,136.7mm³ (h = 147.5 r = 18).

#### Printing

##### Inner_Tube.stl

Print on its side otherwise it'll be very brittle and snap in normal use.
0.12mm layer height, use support (only touching buildplate), use adhesion, 40% infill.

##### Top_Cap.stl

0.2mm layer height, no support, no adhesion, 40% infill.

##### End_Cap_6mm.stl or End_Cap_8mm.stl

It's threaded (1/2 inch 20 TPI UNF), so use a low layer height.
0.12 layer height, no support, no adhesion, 40% infill.

##### Tube_40mm.stl

My advice is to print on its side otherwise it can be brittle enough to snap during normal use. It might shrink after cooling, measure it and expand by the amount it shrunk. It will look nicer if printed vertically though.
0.2mm layer height, use support (only touching buildplate) + adhesion. 40% infill.

##### Tube_40mm_account_for_shrinkage.stl

If your print shrinks the same as mine, use this instead. Print on its side.
0.2mm layer height, use support (only touching buildplate) and adhesion. 40% infill.

##### Wrappable_Mesh.stl

Weird one to print. In Cura, Set number of top and bottom layers to 0. Set infill pattern to Lines or Zig Zag. The same probably applies to other slicers, have a look at this for more information and inspiration.
Use layer height 0.12. 66% infill, no support, no adhesion.

Print Settings

Printer Brand:

Creality

Printer:

Ender 3 Pro

Filament: eSun PLA+ Black
Notes:

0.4mm Nozzle used.

Category: Sport & Outdoors