3D Printed Train Whistles

WARNING: HIGH PRESSURE COMPRESSED AIR CAN CAUSE INJURY. USE APPROPRIATE PPE: HAND, EYE, AND EAR PROTECTION. Santa Fe 6-Chime: https://www.thingiverse.com/thing:7346802 Northern Pacific 5-Chime: https://www.thingiverse.com/thing:7346813 These steam whistle replicas are designed to resonate with compressed air (Only been tested to 120psi). Do NOT use steam. The inlet adapter is designed to fit a 1/2" NPT control valve. If a 1" NPT valve is available, the bowl inlet adapter is not necessary. Adjust the languid (bowl) plate centeredness and bell spacer gaps as necessary for optimal whistle resonance. Materials tested: PLA, PLA-CF Layer Height: 0.20mm Infill: 25% Wall Loops: 6 May 05, 2026: It hasn't ceased to amaze me the amount of support and engagement that this community has offered. Reading the comments is truly inspiring and uplifting to my day, and I want to thank you all! Doing this project, it was focused on being experimental with the shop's air supply. With the recordings, I just wanted to get it out there to share. I was not expecting the amount of response that it's gained, so I'll answer some questions here that I've been receiving! Q&A Q: Will you be releasing the Big Boy whistle 3D model files? A: Yes, I have completed the files for a 4" variant that is more user friendly, I just need to print and test it first. -May 07, 2026 Q: Will you take whistle requests? A: I don't plan to do requests at this time. My schedule would be packed with plenty of 3D modeling if I wanted to get to ya'll's requests, as much as I would love to! Q: What PSI/CFM and fitting requirements are there for these whistles? A: I roughly estimate my shop's air supply to be 50 CFM @ 120 psi, which isn't typically available for hobbyists. I had better luck with using no less than 1/2" NPT fittings. These were mainly designed as a proof-of-concept, but seeing the amount of engagement this has gotten, it inspires me to look towards researching extracting more air flow out of smaller air sources so these whistles can be enjoyed by the community more easily. Q: What filament and print settings do you use? A: I used PLA basic and PLA-CF for these designs, I have not tested ABS/ASA or PETG. Wall Loops: 6, Infill 25% grid, Layer Height: 0.20mm Q: Can you print these in metal or use printed wax for casting? A: It might be possible, HOWEVER, these designs were experimental and meant only for PLA and compressed air. If a real application of steam was used, the thin areas could warp. If the bell lip was as thick as the surrounding wall thickness, it might be possible, although I have no resources for metal printing. Q: Will you sell these whistles? A: I don't plan to sell pre-printed whistles as a small business, however the 3D files are free and available on Thingiverse if you can print it or know someone who can. Q: Are you an engineer? A: Nope, I am a hobbyist that uses Blender to design these 3D models. I would imagine software like Solidworks would be more suitable for these engineering applications. Q: Can you use steam with these whistles? A: No no NO, never use steam with these plastic whistles, they will warp and be met with rapid disassembly. Q: What whistle valve is that? A: The whistle valve is a United Brass Works 1/2" NPT valve, which is available online at multiple sources. This was not the primary valve used for the tests, it's mainly for the pictures. I had best results with standard modern 1/2" NPT ball valves. May 08, 2026 I’m still printing the 4” diameter Big Boy whistle up for testing. Reading through these comments, I’m inclined to extract more airflow out of lower pressure systems for easier use, since the direct connection I drew up requires a high CFM, which not many people will have access to. I have an idea to design a 3/8-inch NPT air nozzle with a Venturi to provide more air flow as opposed to pressure. This means going back to the first bowl design with flow in mind, since the real bowl design accounts for steam expansion, but with compressed air, we just need to focus on the air flow. This is interesting because this is precisely how I was blowing the first whistles I drew up without the direct connection; an air nozzle was pointed into the inlet with a gap around it so it acted like a Venturi, giving more air mass to flow through the whistle. This is what I aim to achieve so the community can enjoy these more easily!