The inspiration for the K-Nex Dragon comes from the work of Theo Jansen. His machines are impressive in size and design. He uses a simple concept in mechanical engineering and combines this with an algorithm based on the principles of evolution to create the lengths of each rod in his design. The result is a walking mechanism which is the basis for all of his Strandbeests.
The driving mechanism is a modification of a four bar linkage. This mechanism is what drives the each leg in its motion. the path of the feet only touch the floor once in their circular path. This allows alternating feet to be placed on the ground as the other feet are off the ground on their way along their path. This creates a walking motion
I use this idea to create a walking mechanism which can be used to create a creature like mine or one of your own.
Step 1: Supplies
You'll need a lot. This design uses K-Nex Micro. There are three pieces you'll need from the regular K-Nex sets. The K-Nex micro have converter pieces which can connect the smaller K-Nex to the larger version.
K-Nex Motor - Green
White Connecter - 2
Yellow Rod - 1
Blue Spacers - 4
Blue Spacers - 20
Grey Spacers - 10
Black - 10
Yellow - 80
Grey - 76
Red - 45
Purple - 30
Blue - 30
Orange - 10
Green - 100
Orange - 10
Purple - 4
Yellow - 75
Grey - 90
Red - 40
Black - 2
These parts which can connect with other connecters. I have them listed as one connected part.
Purple/Purple - 16 (Purple connected with a purple)
Purple/Grey - 10 (Purple connected with a grey)
Grey/Grey - 10 (Grey connected with a grey)
Step 2: Motor Cage
Here is a picture of the motor cage. They key part here is to add the converter piece so that they are in opposite direction. You want to the motor to spin each axel so that they are opposite in phase. Thats a fancy way to say right side should be up when left side is down. This alternates the leg motion. Think about it. You wouldn't walk with both legs moving forward.
Start by placing the yellow rod into the green motor. It may take a bit of force to push the rod through. Then attach the white connecters and red converter pieces to build a housing for the motor.
The key here is to attach the neon green converter pieces pointing in opposite directons from each other. See the fourth and fifth picture for details.
Then follow the design in the second picture to build the cage.
Step 3: First Leg
Gather your pieces and repeat this step 4 times to have a total of 4 legs.
Step 4: First Leg Cage
The cage which holds the legs are meant to modular. You can add more cages to cages and with some engineering skills, you can create more legs for your beast. For now, build only one.
Do not worry if it seems like in the last three photos the two rods will not stay in place. Once you have everything together, they will stay together.
Step 5: Attach First Leg to Motor Cage
I used a red connector to keep the driving arms of the legs attached central rod. You will need to remove this when you attach your legs to the motor.
I found it easiest to attach the cage first, by connecting all the red rods to the motor cage. Then i connected the central rod to the motor. See pictures.
Step 6: Attach Second Leg
Go back to step 3 and build a second leg. When you get back here, you will have a mechanism which can walk.
Step 7: Add Feet
The feet can be altered but should allow a stable bottom else your mechanism will be unstable. I found this design works well.
Step 8: Add Tail
The key to the tail in Picture 3. Notice the difference in size of the two parts. One is smaller than the one sitting beside it in Picture 3,4, and 5.
This difference in size makes the tail point downward, which helps the tail to swing as the beast walks.
It can be tricky to attach. The pictures as the end of this step have a lot going on.
You want to connect the yellow connectors off one end of the tail to the black rods attached at the back end of the beast.
Step 9: Add Neck
The K-nex can flex.
This feature can be used to create curves. Notice the curves in the neck. You can flex the K-nex pretty far before the connection breaks. One draw back is the connectors tend to break if stressed too far.
The key here is in the last picture. The blue rod connected to two red connectors attaches the neck to the top of a leg. When the leg moves, it pushes the neck side to side. This creates a gait in the beast and adds a nice aesthetic feature.
Step 10: Add Face
Use the curves to create a contour of a face. Here is one resembling a bird or reptile face.
Step 11: Add Wings
Use the curves to create wings. Their only restriction in size is they must not hit the legs. As long as they can supoort their weight and do not hit the top of the legs, they will be fine.
The key is to attach one end of the wing with an orange rod to the hind legs of the beast. When the legs move, the wing will flap.
Step 12: Final Walk
Now you have your own baby mecha dragon. What other beasts can you create?
Sorry about the poor quality of the video but you can see the dragon's gait and see how it flaps its wings.