One-piece sandblaster gun

One-piece sandblaster gun. It does wear out but since it's under 20g of filament I don't mind replacing it. Sand nozzle is 5 mm diameter, air nozzle is 2.5 mm, distance between nozzles either 5 mm or 3.5 mm. I use sand tube with internal diameter of 16 mm, and air tube 10 mm internal diameter (gun has 11 mm external diameter for air).

It's my first experiments in printing sandblaster guns and I plan to continue evolving it. These models I successfully used for cleaning car brake calipers, printed from PETG. Pressure used ranged from 4 bar to 8 bar with default of 6 bar. 4 bar in my opinion works poorly and 8 bar is about 2 times faster than 6 bar and suitable for quick overall cleaning.

I've tested a number of designs but my test were not scientific. So far the main factor affecting performance is distance between air nozzle and entrance to the sand nozzle with 5 mm and 3.5 mm both working good.

After some more tests I scrapped branch with 3.5 mm distance from air nozzle to media nozzle and left only 5 mm one. Tighter one showed uneven nozzle wear. I also added gradual change of diameter before air nozzle but that didn't seem to affect performance in a significant way.

For me 3 mm air nozzle diameter works better than 2.5 mm, so I'm using that one. It allows me to get a bit better performance without need to ramp up the pressure. Between 5 and 6 mm media nozzle diameter I prefer 5 mm as it give a bit more speed to the media.

I've tested the vacuum the gun pulls and unused one printed with 0.2 layer height pulls about 0.53 bar and after a bit of usage media nozzle becomes smoother and it pulls 0.57 bar of vacuum. Best result so far is -0.6 bar of pressure.

You can check my demo video with real-time sandblasting: