Slip-on moderator for Umarex Notos

This is a moderator for the Umarex Notos air gun.  This is not for firearms use and only fits on the Notos air pellet gun.  This slides over the built in moderator/barrel end of the stock Notos air gun and does not require any modifications of the Notos.  I have included the STL and a Creality Print .3mf project file with settings to help print it.  The project file in my experience also imports into Orca and Bambu studio to get the print settings.

This is a from scratch creation using Fusion 360.  The basic design is similar to the 'Notos Slip-on Moderator Extension' by MuttT over on m a k e r w o r l d.  I designed this to have holes in the baffle cones and staggered them to each cone to help create more turbulence to slow the air down.  In my testing, it has helped to reduce the sound level over just standard baffle cones.

I have included printed threads in the design that are meant to use M3 x 4mm set screws (4 of them) to secure the barrel on.  I created the set screw locations to match the pin positions so that the set screw can go directly over those pins to minimize any damage from the set screws.  It doesn't need to be very tight... just snugged up since they go into pin holes a little bit near the end of the barrel and tighten onto the factory pins that are in the pin holes.  When installing the moderator,  I aligned the set screw holes as close as I could while putting it on and then I used a toothpick in the set screw holes (probing as I turned the moderator) to check depth to see when the holes were over the inset pins, before snugging the set screws.

Instead of set screws, I have also used some strong tape to hold the moderator on during testing without any problems.  I don't suggest that, but it did work during testing.  This is with the stock Notos power.

The barrel of the air gun (built in moderator), that this slip on moderator goes over, tapers to a smaller diameter a little as it goes back away from the front of the barrel.  I used a layer or so of painters tape to help snug it up just to make sure there is no play between the moderator and the barrel in that area.

I highly recommend a filament that can resist heat instead of PLA.  You don't want to leave it in the sun and have it warp and the pellet end up hitting the moderator which could be dangerous.  I personally use Sunlu Silk PLA+ and Sunlu PLA+ 2.0 and use it inside without any problems but over time I don't know how it will hold up.  A better filament that can handle being in the sun/heat would be the better plan.

I did some non professional sound level testing using the 'Niosh SLM' iOS app with the phone about 2.5 feet directly to the right of the exit.  I don't have professional audio equipment so certainly not 100% accurate but the app seems to be the most consistent of any other sound level/db app I have found and the organization seems to care about getting the best results from the iphone so I am including the info for what it's worth.

-98 db(c) Default Notos

-89 db(c) MuttT's design on m a k e r w o r l d

-86 db(c) This design

The 3mf project file has multi-color set to change filament color at layers 649 and 719 if you want to print the fake grip area as a different color as I have done.

These are other important print settings...

• 0.2 mm layer height

• 4 walls

• 15% infill

• Arachne wall generator

• Bottom Shell layers 4

• Brim type Outer brim (7mm width, 0.06 mm brim object gap)

Changes:
2025-01-01 (v5): Added chamfer/fillet to exit hole