May 11, 2026
Description
TOOLS NEEDED:
PARTS NEEDED:
INSTRUCTIONS:
For most of my sirens, the rotor/chopper is always the first step. I'd recommend printing with 100% infill for the longest winddown and the best durability. If you decide to print with less than 100, use a conical infill pattern so the “grid” infill doesn't throw the rotor off balance.
Then print the stator. This should also be done at high infill since under all the wind and vibrations the rotor makes, it can easily warp around.
To assemble the core itself, bolt the stator onto the motor with the M4 bolts. Make sure the bolts aren't too long as they can damage and seize the motor if screwed in too far. Then, press fit the rotor onto the motor shaft. You may have to adjust the shaft size on the rotor depending on your printer to get the right friction fit. I usually get mine started by pushing down on it and then use my body weight to push on the top of the motor while the chopper is being supported by something underneath. If the friction fit is extremely tight, You can use vice grips and twist on the rotor (this is also the safest option for the motor)
Once you have the core assembled, I'd make the horn ring next. There are multiple options and sections you can print it in depending on your printers size. This is where you'll need to plastic weld all the sections cleanly together with a soldering iron. Although a hot glue gun will also work fine.
Next, print the base piece. This should screw into the bottom of the horn ring with the small wood screws to hold it in place. After it's assembled, you can slide the core into the horn ring from the top. Make sure the horns are all lined up with the ports and glue around the top to holt it in place! I'd also do a few spin checks to make sure there is no scraping before you glue because sometimes the horn ring can put pressure on the side of the stator.
From here, all that's left is the top cone. After you print all the sections, weld them together nicely so they all line up with the mounting points on the horn ring. You'll want to solder wires to the motor before you attach the top cone. To attach it, use the bigger wood/sheet metal screws and mount it to the rest of the siren.
If you would like to make the mount, first print it out and drill holes in the PVC pipe that correspond to where the holes are located on the mounting piece. Then, screw the two together so it holds. use 8 M3 bolts to mount it to the base of the siren.
If any steps are confusing to understand, I have a “Siren Help” channel on my Discord server where I'll be active and able to answer questions!
License:
Creative Commons — Attribution — Noncommercial — Share Alike
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Haroldhihat
