1/4 Scale Federal Signal Eclipse 8 Siren

DISCLAIMER

The information provided here is offered on an AS-IS basis only. While I have efforted to make this helpful to you, I do not offer any warranty or guarantee of any kind regarding any aspect of this information, The information below may be subject to change without notice. The full risks as to the use of this information are assumed solely by the model builder. 

(This really isn't that bad, I promise)

You will need….. (or equivalent) 

• https://www.amazon.com/dp/B07P6X8QM1
• https://www.amazon.com/dp/B0BB2V8PNK
• https://www.amazon.com/dp/B076H3XHXP
• https://www.amazon.com/dp/B0D9D3K518
• M4 and M3 Screws and Nuts
• Wire and Connectors
• Up to a 12 Volt Power Source

This was printed on a Neptune 3 Pro which is 225x225x300

M4 nuts need to be 6.83mm in size for the motor mounting

4 of the M4 bolts need to be 50mm long, the rest of the bolts do not need to be exceptionally long

Holes are not set for inserts, all bolts are paired with nuts

All the leg pieces will be printed X3

The horn will be printed X8

The pieces are keyed so they can fit into each other and align… everything goes together like a sandwich and should all be flush when assembled correctly.

A counter intuitive approach is needed for the rotor. Set your slicer up to print with as little filament as you can. This will help mitigate any balance issues with the rotating mass. The super capacitor will handle the wind up and wind down. 

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To mount the rotor to the motor shaft, insert the coupler on to the motor shaft and tighten down the set screws. give about 1mm of clearance from the motor body.

While we're here, turn in the other set of set screws on the coupler that are not on the motor shaft as they will need to be screwed in so you can insert the rotor onto it. Put the rotor onto the coupler, you should not need to use a lot of force to put it on. 

The rotor has two holes in the spindle at the top, line these holes up with those second set of set screws you just turned in, take the allen key through the holes in the rotor to find the set screws in the coupler and BACK OUT THE SCREWS until you feel resistance. This will lock the rotor onto the coupler. give it a spin and check for any significant wobble, hopefully there should be none or very little, if not you'll need to do some troubleshooting. 

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To line up the rotor we need to take 6 of those 6.83mm M4 nuts and insert them into the conveniently shaped hexagonal shaped holes in the motor mount plate. to do that take an M4 bolt and tighten it down until it pulls the nuts into the recesses, then back it out until the end of the bolt is flush with the nut. 

Now take the upper and lower chopper halves and bolt them to the mount plate using those 50mm bolts and tighten them down just past finger tight, notice how the pieces have either bumps or holes on them. the bumps line up with the holes and will serve to keep stuff in place.

Now insert the motor with your rotor attached into the holder. leave the shield on the motor attached and slide it so it covers up the vent holes by the brushes (this motor is not gonna be stressed enough to make any heat). Line it up so the ports in the rotor and chopper align, then turn the each of the six screws so they're just starting to grab the motor body, You can set this down on the table so you have something flat to work on for this part. 

NOW THIS IS THE TRICKY PART… PATIENCE IS KEY HERE… Notice how you should have three sets of bolts clamping the motor case at the back and front. By turning those screws we are adjusting the placement and tilt of the rotating assembly. You need to adjust each screw to center the rotor up. For each screw you tighten on the top, you need to loosen another one on the top, same for the bottom as well. The assembly will move in the direction that the screw is pushing it

If you have that 390 motor I linked above you can take a second coupler and put it on the back shaft and use it to give the rotating assembly a finger spin to check for rubbing. Just keep at it until you find the sweet spot. It takes myself about 5 minutes to get it dialed in.

Do not turn any screw more than 1/8th turn at a time, going too tight will make the whole thing “walk” which will push it out of alignment vertically. These do not need to be more than finger tight. You can always start over if you really got it messed up.

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This uses low voltage DC so as to be kid friendly. However this project does require some soldering and other basic electrical skills. If you've never done, or don't know how to do these things, get someone to help you. The power box included works with the linked power module. 

Power modules you get online tend to be adjusted to maximum power so before hooking one up to the motor, adjust it down. The set voltage for this setup to get good results is 2.47 volts. Applying 12 volts straight to the motor will just make it sound like a Model A. 

The Super Capacitor linked goes parallel into the circuit anywhere between the power regulator and the motor. Red dot on the motor is positive terminal and that does need to be fed positive voltage to spin the right direction. 

look to get a voltage regulator as opposed to a speed controller. Speed controllers only slice the power up, and a change in supply voltage will cause pitch fluctuations.