Intro: Steampunk Auto-folding Wings
I have made for my daughter steampunk wings which can fold open and closed with the help of Lego Technic parts.
I was running out of time for the "make it real" contest, so I posted this instructable before I am all done, with the intent to improve/expand as I go... I have not yet been able to do the fabric on the wings, but the rest is done and working.
This is my first instructable, so bear with me as I tweak my style...
So where do you start? You find wings you like that fit the style... Leonardo DaVinci was a prolific drawer and researcher of wings, so I started with looking for images by him, and found one that my daughter liked and looked doable...
Finally, what would I do with the printer? It'd print the parts I used and make them look more Steam Punk and less Lego... And then more, obviously.
I'd also like to start a little 3D printing workshop to allow others access to affordable 3D printing...
Step 1: Design the Mechanism
I then designed the mechanism for the wings in Lego Digital Designer, and subsequently built it for real to test whether it actually worked...
Step 2: Transfer the Design to the Wings Image
Satisfied the mechanism worked I took the measurements of the Lego mechanism and transferred it to the image from DaVinci and then I printed it on 1:1 scale. After that I drew the actual shapes on the drawing and then transferred those to foamboard to create a real size prototype.
With a working prototype in my hands, it was time to go for the real thing: multiplex.
I had the straight parts sawed to measurements and the long, curved spines were jigsawed. After that I drilled all the holes and connected all the identical parts for left and right to eachother and finished them with a belt-sander. I rounded the square ends of the straight parts and made certain all parts for left and right were smooth and identical.
I also created a 2nd set of long spines in 1mm thick balsa wood, so I can cover the fabric (and coach-bolt heads) once it is attached...
To connect the parts I used coach-bolts, metal washers (for behind the nuts), nylon washers (between the parts so the joints move smoothly) and self-locking (nylon) nuts. When everything aligned and worked, I took it apart again to stain, and reassembled. Then it was time for the lego mechanism for the movement...
Step 4: Movement Plate
I made a movement plate, with two slots that move over a pair of coach-bolts as the basis for the mush/pull mechanism that folds and unfolds the wings. On one end I attached the ends of the push-rods, on the other end the Lego mechanism would be attached.
The main mechanism is a rack and pinion system to change the rotation in to a linear motion, and I made it double for stability and strength. The rest is simply a reduction gear system, topped off by a PowerFunction motor with a slip gear (to prevent overheating when the extremes of the mechanism's motion range are reached).
Step 5: Almost Done!
The 2nd bottle slot can be used to carry something... A bottle of water for instance...
Next step is to attach the fabric to actually make it look like wings.
I first intended to make the wings two layers of fabric with the ribs in between, but that proved to be unsuccessful, so I went for a single layer of fabric with bias-tape (bias binding) to make tunnels for the ribs.
The detail images show how I've done this. I aligned the tape to the fabric's cut out points as much as possible. I also made a double zigzag at the top of each tunnel, and folded about 1cm of the bias-tape for even more strength.
When all tunnels are done, take 5x5mm Balsa wood rods, and cut them to size (Balsa is soft enough to cut with scissors, light enough to add virtually no weight, and strong enough to build airplane wings from!) but do not insert them yet.
After they're all the right size, stick the fabric to the main rib with contact glue. As you may recall, I also made those in 1mm balsa wood. Stick that on the other side of the fabric, making sure both pieces of wood align perfectly. Then you can use some carpenters upholstery nails to make it look more authentic.
Once the main rib is reattached to the mechanism, you can insert the balsa ribs to see how it looks... It may be difficult to get the balsa to slide in the folded bit at the end of each tunnel. You can use pins to guide it. Insert the pin through the fabric just below where the folded bit end, but make sure it does not go through the bias-tape as well, then - making side to side motions - slide it's point between the folded bit of tape and the main tunnel part of the tape. Once it is in there, push it in further and make it come out again at the fabric side. Now the balsa rod cannot catch on the folded part and goes where you want it!
Repeat on the other side!
Step 7: Final Touches and Wrap-up
When everything looks the way you want it, it is time to stain the balsa, insert them permanently (and fix them in place with a binding of thread) while tensing the wing fabric.
Finally I added 2 pairs of elastic ties (to at the top, 2 at the bottom) between the free center flaps of the two wings so they're under tension when extended...
As you can see in the last picture, they are pretty impressive when unfolded, and the only drawback I found so far is that the batteries drain pretty fast.
If you fold/unfold them a few times in a row, you can tell they're starting to slow down... I may modify the batterypack so it takes 6 14500 LiPol batteries in pairs (they do about 3.7V each) or triplets (11.1V, tests on the web show that these motors work fine on 12V, and it'll increase the speed too, which could be a bonus). That way I have 3 or 2 sets of rechargeable batteries with a good capacity. If they last a single day, I'm happy... We can recharge them over night! ;)
Step 8: Finished!
In the end I modified the Lego Powerfunctions battery box so that it takes 2x 3 14500 LiPol batteries (nominal 11.1V) as these deliver higher voltage (nominal 3.7V pp) and have a higher discharge capacity, so the motor gets more power to turn and drive the gears.
(I had to dremel through a metal connector pad inside the box so I could separate the 6 slots in 2 sets of 3 and then soldered in extra wires to connect those up to the orginal points. Double the capacity, higher voltage and rechargeable, better all round!)
This results in the wings folding and unfolding faster, which looks better and makes the movement smoother, as it has less tendency to stall...
(Applied mechanics trivia: Friction of moving objects is lower than the friction of stationary objects, so keeping them moving is good!)