Air Raid Siren - hand crank version 2

by MlePh, published

Air Raid Siren - hand crank version 2 by MlePh May 29, 2016


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Autodesk AutoCAD

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31049Views 3924Downloads Found in Mechanical Toys


Remix of my own design. I had a lot of positive response so i desided to redesign it and use metal bearings to avoid friction problems i had with the 100% 3D printed version. Runs much smoother now!

To build this you need these metric [mm] bearings:
(amount x outer diameter / inner diameter / height - link)

I also tried to design it with 3d printed bearings - But did not work that well. I could get these bearing in an industrial store in my town for around 35 €. The bearing are standard sizes - so you should get them easy.


I uploaded two clips to youtube.

Slicer note:

I used Simplify3D to slice all parts. If you print it with MakerWare the parts might not fit together - i found out that MakerWare does not care for the nozzle size. Thats why i had some space between every part on my preview version that was featered on thingiverse. I don't now how cura and other slicers work. You should test it with some small parts like GetrRad2A and GetrRad2B before you print bigger parts - they should fit together very tight.

In case you own a Makerbot Replicator but don't have Simplify3D - i added a .zip-archive that contains all sliced .x3g-files ready to print. There is also a README.txt if you have problems getting the bigger parts printed on your R2.


I use basic AutoCAD to draw my 3D stuff because i use it a lot on my work. It took me about 200 hours to design this siren. I added the drawing file if you want to make changes.


Print Settings

Printer Brand:



MakerBot Replicator 2








Most parts can be printed with standard settings - No Raft, No Support.

Except of following changes:

  • Gehause3 - change filament color while printing to get the text highlighted
  • GetrRad2A+B - print it solid, needs to be strong
  • GetrRad4A+B - print it solid, needs to be strong
  • Kurbel1 - use brim to prevent warbing
  • Kurbel2 - print the top layers solid
  • Rotor3 - print it with high resolution (0.1 mm) and raft to get clean props
  • Schraube1 - print it 3 times
  • Schraube2 - print it 6 times
  • Schraube3 - use brim


If not every part fits after printing you may have to use some abrasive paper. 

Parts like the rotor should be sticked together. 

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Thought about making this but RIP, I open the first file, and it's larger than my build area. (Anet A8 (220/220/200mm)

Hi MlePh,

Is this edge showing in the hole in the back of SirHa_Gehause2 intended ?

Thanks for sharing !


A couple questions:

for the non-solid parts, what infill did you use?

for Kurbel2, what do you mean by print the top layers solid? The head side or the thread side?

Also, why do you mean by brim?

Great design but a bit big for my platform (Makerbot Replicator 5th Gen). It would be nice if the handle was a separate part. I think that would cut down the print size enough to fit my platform

Hi, would you mind posting, or sending me a few of the files... it just doesn't quite fit in my printer, but splitting STL is not so simple. If I have a STEP file I can easily split them, then I will glue them together. I saw your other design where you did just that, so I thought it was a great idea, but I really want the bearing version. If you don't mind, I would need the following files:
If you don't want to share the STEP files, I totally understand, no problem.
You got an amazing design here! I'm planning to use this at my son's soccer games, only for the goals of course... :)

Nevermind! I saw the DWG file now, and it is a 3d solid. I imported it in Fusion 360, I only have to stitch a few faces together and ready to split. I started printing some part... I'll post back at the end when all done.

Great Idea to use this at your sons soccer games! I'm sure this will get the right attention! :) You shoud write his name on the siren instead of the tem "Make It Loud"-letters!

I have seen a few videos of fusion 360 and i think i might use try this program too. AutoCAD - which i use now - is very old school and not really convenient if i have to draw things in 3D...

I have more than half the parts printed now, and every time I print a new part, I am impressed by the attention to details you put in this design. You wrote that you put 200 hours in this, and I believe it for sure, really nice design, everything (so far) fits perfectly. Doing all this in AutoCad must have been a pain!!!

For sure Fusion 360 is a big step up from AutoCad, and it is also very cheap. If you use AutoCad for your business, I would consider 1st SolidWorks or AutoDesk Inventor, but they are more expensive than Fusion. If price is a big problem, Fusion will do the job, but is a bit harder to master than the other 2 (maybe only because I have used SolidWorks for many years).

I won't put his name on it, he would be quite embarrassed... haha, but I am considering putting his team on there, we'll see, anyways that is a simple part, I can make a few different variations! Ok, need to setup the next part of the siren to print now!

Ok, finally received all my bearings, and did the assembly tonite. I have a couple of questions...
1-The very thin "sticks" at the top of the unit, like 1mm wide, do they do anything for the sound, or are they just for the looks? I have a few that broke and wonder if it will be a problem (I don't know yet because my whole assembly failed).
2-The 2 small gears... I believe that 1 of the 2 has the wrong file here. Both gears should have a tiny pin on both ends, to go into the small bearings. But 1 of the 2 gears has a flat, no hole to insert the pin, and no pin. That does not work when assembling, because the flat goes right against the bearing that is in the top piece written "make it loud" on it. Could you please verify that file?

For general feedback, I had lots of filing and sanding to do, but that is not a complain, of course this will depend on each printer. That is not a problem at all.
I broke the edge of the part "make it loud" when pressing the bearing. The hole was too small a little bit... I will re-print and make the hole just a nerd bigger and it will be all good. Also, I broke the handle almost instantly. I had printed it with 50% infill. I might do 100% next time. But really, it broke because of me, the rotors were too tight in the housing and not turning freely. Nothing that some sanding didn't cure, but I did it too late obviously, my bad.

Ok, if you can let me know about that small gear, then I can re-print a couple of parts and get this thing working! (hopefully...).

Nov 19, 2016 - Modified Nov 19, 2016
MlePh - in reply to DarthBane

1 - those sticks are for safety. If you build the siren with the handle on top your finger could get into the rotor. A friend of mine hurt herself on the first siren version... so i fixed it in this one

2 - i will check the files i have uploaded! Could be possible that there is a wrong file!

How did the bearings fit? They should fit exactly and stay in place when installed. That you have had to sand a lot sounds a little bit like your slicer settings are not optimal. Maybe the extrusion multiplier is a little to high - this causes the prints to be slightly too big.

Nov 19, 2016 - Modified Nov 19, 2016
DarthBane - in reply to MlePh

well, the file is fine after all. I assembled it wrong. I don't have access to a CAD system at home, so I was guessing on how to assemble it. When I went to work, I saw that I did something wrong. Sorry about that, your files are fine.

For the bearings, the big one fit in perfectly, good tight fit, no sanding required. On the 4 smaller ones, I would say 2 fit as is, 1 with light sanding, and 1 with heavy sanding. And I know why... the zero on my printer was a bit too low, causing the 1st layer to be wider than the rest. So the bearing holes that were face down on the printer bed had the 1st later too small in the hole, simply needed to remove that extra plastic on those. Otherwise, everything fits superbly nice!

And also when I took it apart, I realized that it was not the handle that had broken, but the gear, where it goes inside the handle (the big hex). The reason is my assembling this all wrong... Now I just finished re-printing that big gear, took about 10 hours (I use PETG and have to print slower than PLA)... at about 9 hours I ran out of filament!! Starting again now, with a different color... just to get it going. I will re-order the correct color for my assembly. Hopefully later today I can finally test it!!

Hi MlePh, I got the thing done, but it doesn't quite work yet. I realized that my 300$ printer might not be super super accurate. It is really good, but, here we have a rotor that spins at a few thousand RPM inside a round cage, and i can see that neither the rotor nor the cage are perfectly round. Fortunately, my cage is white and rotor black, so I spin it a few times, take it out, and i can see where it rubs. Dremel to the rescue! I got it pretty good, but now the handle broke... haha, I am not lucky so far. What breaks the most though, are those little pins that go inside the small bearings. Actually only 1 of the breaks, it probably has the most stress on it. Fortunately, I am a CNC programmer, so I will make those little pins out of aluminum, and they won break anymore. That might take a few weeks before i get that done, because customer's jobs come 1st of course. I'll report back when I get the pins done. Just wanted to let you know where I was with the project now.

Sounds like you really had to try a lot of things! Hope it will rund with the CNC made pins! Have you already tried to print the pins with a brim and 100% infill?

I am really interested if you will get it up running!

Yes, the pins are 100% infill, but they shear (1 of them, always the same one). Probably a small alignment issue between the 2 bearings (this gear has a bearing on both ends, so the 2 bearings need to be really in line. Maybe in my print they are not 100% in line).
For the pins, as the shop is pretty busy, I got another idea... I will print the pins with a hole in them, and insert a steel nail inside. It won't shear anymore... I should be able to try that soon, I'll let you know how it went!

Nov 25, 2016 - Modified Nov 25, 2016
DarthBane - in reply to DarthBane

Alright, here's another update:
The pins with the nails in them worked perfectly, now it does not shear and i can feel the whole thing turning "rounder". But, although now i can make it scream, it does not turn as fast as yours (in the video). So the sound is not quite that of a siren just yet, it is too "low" of a tone. I noticed that the main big gear which is connected to the handle had a play of about 3mm along its axis, so I printed a spacer to eliminate it. After that, there is no play, everything is looking good when turning slow. But I still can't turn as fast as you. It's like it reaches a maximum RPM and I can't crank any harder, it won't go faster. I look at it while turning, and the back of the unit, the housing itself, sort of bends with the handle turning. I think it is too thin and has too much flex in it (I use PETG), so the gears inside can't stay straight. Now this is starting to be a major operation!! I might make a new housing, thicker on the back, to avoid the bending... but... not sure when I'll get to it now. This would require a new handle too... I just can't make it work as is!! :(
If you have any idea from your experience, about why i can't turn it faster, let me know!!

I too am interested in finding these bearings in the United States. Thanks!

I can't tell you where to get these in the US. I'm from Europe. But if you know - tell me so i can add an link in the summary! Thanks!

Where can I get these bearings in the United States?

I can't tell you where to get these in the US. I'm from Europe. But if you know - tell me so i can add an link in the summary! Thanks!

Sorry to ask a stupid question, but none of the Gehause bits fit my Replicator 2 Build Plate. It asks me if I want to scale it down. I can rotate some of the pieces so it looks like they may just about fit, but there are crazy overhangs which looks like they may need supports.
Do all the pieces (including SirHa_Gehause1.stl) print on a Makerbot Replicator 2?
Thanks again

Ignore this comment. I rotated it until it fits :)

Still worried that slicing it with Makerbot Desktop will mess it up..

Hi, is there any chance to get a pre-sliced version of the model? I dont have simplify3D but do have a replicator 2.
If not, how can you print a brim using Makerbot Desktop slicer?
Many Thanks!

do you mean the x3g-files?

Yes, the x3g files.
I think I might need to replace the print bed too. Tried printing gehause1 twice but it peels off the build plate at the edge. The second time it took the blue tape with it!

Jun 13, 2016 - Modified Jun 13, 2016
MlePh - in reply to andrelambrechts

OK i thought this is only the case at my replicator 2... looks like this happens to all R2. If you print things with the maximum build size the extruder touches the end stops on the Y-Axis.

But you don't need to replace anything - there's a simple trick for that:

When you start the print the extruder moves to the front and waits there until the temperature is high enough to start. In this position the motor of the Y-Axis is unlocked. So you just have to push it to the front to get the right offset to the endstop. Worked fine for me.

I uploaded a zip-archive with all parts sliced with Simplify3D

very cool, thanks! I ordered a glass print bed. Think mine is warped causing the edges to lift up while printing.

Jun 15, 2016 - Modified Jun 15, 2016
MlePh - in reply to andrelambrechts

also a problem i had in the past... good idea to order a glass print bed! I also have one.

Leider etwas zu groß für meinen K8400 aber sieht echt genial aus!
Danke und für später einmal gespeichert

Das größte Teil ist Gehause1. Es gibt auch eine kleinerer Variante ohne den Griff. Vielleicht gehts mit deinem Drucker!

Multiple question, maybe i haven't read the description enough well but anyway

What size is required for the plate of the 3d printer ?

Can/will you make it with a smaller size (120120120 ? does it fit ?)

BTW great job it's awesome :D

It's designed to fit to a Replicator 2 build volume (28.5 x 15.3 x 15.5 cm). This version can't be scaled because of the metal bearings.

But there is a remix of my other design that might fit to your printer:

Air Raid Siren parts (for 5.5" x 8.5" bed)
by don3sch

Aw dude that's awesome !!!, (minor problem the part is 10 mm too big each side XD but i will resized it. Maybe in my industry i will find a dude that can make me special ball bearing (metallurgist)

I like you, really that's awesome i love the sound in the video i will make it a soon as i could :D

Multiple question, maybe i haven't read the description enough well but anyway

What size is required for the plate of the 3d printer ?

Can/will you make it with a smaller size (120120120 ? does it fit ?)

BTW great job it's awesome :D