Introduction: Pocket Bat Signal Design

Picture of Pocket Bat Signal Design
For the 3D Design Contest I decided to make things more challenging so I set some additional restrictions on myself.
  1. My design must be able to be 3D printed using pieces that people can get from Instructables by winning free prints. This means no prints can exceed the 3"x3"x3" bounding box that Instructables has set for free prints.
  2. The design must have moving pieces.
  3. The design must be packed for printing in such a way that no more than 3 prints are used to complete all the pieces.
This is what I came up with. It's a pocket size bat signal, with a crank to change the angle and all the fixtures needed to add LEDs when all the parts come. Now you will never be without backup. Here a noise in a dark alley? Strange creaking downstairs? Is your boss just being really annoying? With you're own pocket bat signal you need not fear because you can signal the Dark Knight at will! Feel free to customize the symbol, all the files are attached. A pumpkin or ghost would be perfect for use in your desk Halloween decorations at work.

Here's how the design breaks down:
The very bottom piece will be specified in the flexible rubber material. This pad snaps into the base piece and gives the whole assembly a non-slip surface to sit on. The base is hollow with holes for the rubber pad on the bottom, holes for screws to secure the lid on the top, and one hole in the back for a panel mount switch. The batteries for the LEDs will be housed in the base, as well as anything else you choose to hide there.
Bolted to the base is the lid, which includes the supports for the barrel. The thicker support on the right has a pass thru for wires running from the LEDs to the battery, and a counter-bored hole for the axle. The left support has two straight holes, the upper for the larger gear, the lower is where the lower gear and handle meet. The axle in the right hand support has a hole through the middle where the wires for the LEDs will pass through.
The large gear on top is fixed to the barrel while it spins free in the support. It has a 1.5" pitch diameter, 48 pitch (72 teeth), and a pressure angle of 20º. The lower gear spins free in the support and is attached to the handle. It has a pitch diameter of .25", 48 pitch (12 teeth), and a pressure angle of 20º. The gear ratio is 6:1 from the cranker's perspective (6 turns of the handle would turn the barrel once).
The barrel is 2" long and has a plate part way up that allows 5mm or smaller LEDs to poke through. There is also a bolt, thru hole to attach a PCB to the underside. There are no LEDs directly behind the symbol to help cast a sharper silhouette. The black cap on the bottom of the barrel allows access to the LEDs using a twist lock design. The two nubs on the cap engage two matching slots on the barrel. The boss that holds the axle on the right also has a pass thru hole for the LED wires.

To meet the requirement I set of not using more than three prints I stacked the small components in the empty space inside of the bounding box made by the pad, base, and lid. The printer will simply fill in with support material between pieces. When the support material is removed the pieces will come free and then can be assembled. I managed to get all the pieces into 2 prints, with the second print being the barrel by itself.
The whole thing will be put together using glue and a four #8 screws. The assembly is designed so that even when it is glued together you still have access to everything in case there is an electrical failure.

I did the design and modeling in CATIA V5 (The colors in the pictures are only so you can see the different parts in the model, the final product will be painted). Attached below are two .zip files with the CATIA files."Bat Signal" has the assembly in it's proper configuration, "For Print" has the stacked configurations for printing along with the .stl files. The .stl files are attached separately as well for anyone with their own printer. If you need a different file type let me know and I'll do my utmost to convert the files for you. I'll be sending out for the first print with in a couple days and the second as soon as I earn another print. Once I receive them I may tweak the design if necessary, so you may want to contact me to make sure the .stl's are up to date. If you want to know the moment I finish assembling the final build, complete with circuit, make sure to subscribe. Thanks for reading to the end of that wall of text, please feel free to comment or ask questions.
Na na na na na na na na Batman!

EDIT: 10/08/2012
You asked for it, ok not really, just JerryBYong but that's semantics, and it's here: A barrel with the Dark Knight style logo. There's a picture above and .stl file below.
Both prints are in the queue for printing at Instructables. As soon as they arrive I'll post pictures here and a guide for the construction of the LED circuit and general assembly.
Thanks for all the comments and constructive feedback, keep it coming.

EDIT: 11/01/2012
The pieces, or most of them, arrived today! They all turned out better than I could have hoped for. The fact that the rubbery bottom pad turned out perfectly plus the fact that nothing broke during the separation and cleaning or shipping is awesome. Unfortunately the piece with the small gear didn't make it into the box. I'm not sure if it broke or just got lost in the processes but I can see where it was printed. Regardless everything will go together except the handle and I'll be posting a guide to the circuit and assembly soon. I've attached a couple of pictures of the pieces below.

EDIT: 01/19/2013
The build for the Mk. I is complete and documented. Check it out HERE.


AnimeAlisha (author)2015-06-07

OMG I love this !!! I really want to print it but can you separate the parts and save it as a stl for the "Print_Block1" file please ? The place where I print might struggle with the parts and having supports for it.

bwrussell (author)AnimeAlisha2015-06-30

Sorry for the delay, didn't get a notification of your comment.

We're in the middle of moving but as soon as I get my computer unpacked I'll dif up the files and separate them for you.

AnimeAlisha (author)bwrussell2015-06-30

No it's cool thanks for the reply and YAAAY THANK YOU SO MCUH

bwrussell (author)AnimeAlisha2015-08-27

Ok, sorry this took so long. I have this habit of only remembering things when I'm somewhere I can't do anything about it. Anyways, the zip attached to this comment has all of the pieces as seperate stl files. This isn't an optimized design for FDM but it should get you pretty close.

If you do make one be sure to post a picture or two here!

Rhetorical_Save (author)2014-06-04

ITS AMAZING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! *in batvoice*

fireball1234 (author)2013-06-17

Look at THIS!

biomech75 (author)2013-01-04

You can also use an arduino with the pan/tilt/servos to move the Bat Signal

bwrussell (author)biomech752013-01-04

That's something I'm going to look at for the Mk.2 or 3 but finding small enough servos, as well as a small servo controller for the digispark, is going to be a challenge.

amandaghassaei (author)2012-10-05

this is really well done! I like how it's press fit too. one question, I don't quite see how the handle on the base connects to the gear, can you explain or post a pic that shows how this works?

bwrussell (author)amandaghassaei2012-10-05

Thank you!
Look at pictures 2 and 3. The Big gear gets attached to the barrel and then soins freely in the support. Below it is a small gear, colored black. This small gear passes through, and spins freely in, the support and attaches to the handle. If you look at the picture before the one with my hand you can see the small gear with its attached axle. On the end of the axle is a smaller part that fits into the hole you can see on the handle in the same picture. When you turn the handle it spins the small gear which turns the big gear which pivots the barrel. The ratio is 6:1, so you have to crank the handle more to turn the barrel. The gears aren't strictly necessary, it could have been designed to just be tilted by hand but cranking gears is more fun and I like how it looks.
Does that answer your question.

amandaghassaei (author)bwrussell2012-10-05

those ones change the angle of rotation right, I meant the gear at the base of the light, and the crank next to it. how do those work? Are there gears in the battery compartment that we can't see in the pics?

bwrussell (author)amandaghassaei2012-10-05

There are only the two gears, the ones that change the angle. I think the picture you are looking at is the one that shows how the parts are stacked for printing. Either that or you are seeing the plate where the LED array goes.

amandaghassaei (author)bwrussell2012-10-05

that makes sense! thanks!

bwrussell (author)amandaghassaei2012-10-05

No problem, I maybe should have labeled those better. If I get around to doing a Mk. 2 I definitely want to add rotation around that second axis. I considered it for this one but decided I should get one working before adding more complexity.

JerryBYong (author)bwrussell2012-10-06

maybe you can design the Mk2 with the newer logo?

bwrussell (author)JerryBYong2012-10-07

I'm thinking the Mk. 2 will have a second axis of rotation and swappable logos. That way you can print up any logo or shape you want. It will probably have some improvements in the lighting as well. New circuitry or a lens maybe.

JerryBYong (author)bwrussell2012-10-08

would a magnifying glass work?

bwrussell (author)JerryBYong2012-10-09

It's possible, if one the right size could be found, but I have something else in mind I think I'd like to try first. It all depends on how the Mk. 1 turns out.

JerryBYong (author)2012-10-05

This is friggin awesome. But can you edit one to look like the dark knight rises like this?
It'll be super awesome

bwrussell (author)JerryBYong2012-10-05

Thanks! I was torn on which symbol to use. I went with the classic because it is more symmetrical but some time next week I'll try and do a second barrel for you, and anyone else that wants a more modern look.

JerryBYong (author)bwrussell2012-10-06


bwrussell (author)JerryBYong2012-10-07

The barrel with the new logo is up.

jeffeb3 (author)2012-10-05

To get a sharp image, the light source needs to be a point source, not an array. Why not use one very bright LED? There are some 1W LEDs that would certainly do the trick.

Phil B (author)jeffeb32012-10-06

You are correct. A few years ago at the school where my wife taught the school was producing a student drama and the director wanted a cross projected onto the wall at the back of the stage. He was becoming frustrated with the fuzzy hint of a shadow he was getting. I made a small black paper cross and mounted it in a 35mm transparency (slide) frame inserted into an old filmstrip projector. Suddenly we had a crisp image exactly where he wanted it. We ran an extension cord backstage from the projector hidden above the front part of the audience and a helper could turn it on exactly when needed. As clever as all of the moving parts are in this design, the optical characteristics will not yield the desired effect. The image needs to be focused by a lens.

bwrussell (author)Phil B2012-10-06

This is really more of a trinket than an actual image projector. The focal point is much too close to the end of the barrel, regardles of the light source, to project a clean image at any distance. I'm not an optics guy but I'm guessing it will be well under a foot.
The point was to design it in such a way that it could be printed using a minimal number of free 3D prints from Instructables. I don't expect much of the projector, like I said, if it doesn't project at all then placing a diffuser (tissue or paper works well) over the LEDs will give it the effect of being lit up. If you want to use it to project a clean image there might be enough room to add a lens or if you have the specs of the lens I can whip up a barrel that has a lens holder for you.

bwrussell (author)jeffeb32012-10-05

I went back and forth on that. The LED array is simpler, no driver needed, and cheaper, lots of people have the parts on hand.
Also I'm not sure how this is going to work. It's so small that it will probably be pretty worthless for actually projecting unless it is very close no matter what the source is. By putting the plate in I didn't handcuff my self to one configuration. If the array is rubbish a power LED will easily mount to the plate. In the end it may work better with a diffuser over the LEDs so that it just lights up and looks cool but isn't actually trying to project.

FrozenIce (author)2012-10-05

oh my goodness... that is extraordinary!!! I was thinking of making a bat-signal lamp the other day, but this just blows away all expectations! Wow... really, i salute you (saluting). this is truly a work of art, good job.

bwrussell (author)FrozenIce2012-10-05

Thanks, you really are too kind. Fingers crossed it all goes together when the pieces show up.

mikeasaurus (author)2012-10-04

Great work on the modelling, and extra points for adding those restrictions on yourself. You must post a picture here when it's all assembled!

bwrussell (author)mikeasaurus2012-10-04

Thanks, I most definitely will. I'll probably post a second guide that shows how to assemble it and instructions on building the LED circuit.

About This Instructable




Bio: Why buy when you can DIY? Educated a Mechanical Engineer and trained as a classical cellist I consider myself a bit of a jack-of-all-trades, dabbling ... More »
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