Curved folding makes it possible to develop complex 3-D curved surfaces using non-complex 2-D processing methods such as punching, pressing, or laser cutting. This simplifies the process of producing something that is generally difficult. With a traditional hinge, such as the one found on a door, a pin defines the axis of rotation. However, with a D-CORE joint the axis of rotation moves during the joints motion along the curved surface of the cylinders.One application of this design is in the medical world, where the base of the catapult can be used in repairing spines.
Tongue depressor (or popsicle stick)
Step 1: Print and Cut
Download the outline of the catapult and print it out. Cut along the black solid lines of the Catapult base (the D-CORE), including the ones in the middle of the pattern.
Step 2: Fold
Crease the folds with the designated mountain and valley fold patterns. Trace the curved folds with a pen to help them fold easier.
Step 3: Roll
Roll the curved creases into each other to make the cams of the joint. Secure the edges with tape.
Step 4: Finish Base Assembly
Place the middle band through the two outer bands and tape the end to the opposite cam to create the Jacob’s ladder-like joint.
Step 5: Attach Popsicle Stick
Attach a tongue depressor or popsicle stick to spot labeled “Attach Arm Here” on the catapult base (the D-CORE) with tape. Leave about 2 cm of the stick overhanging the joint on one side.
Step 6: Cut
Cut out the Cap for either the tongue depressor or popsicle stick size depending on what you are using for the catapult arm.
Step 7: Crease Cap
Crease the cap pattern with the given valley and mountain folds
Step 8: Roll
Roll the outside flap into the other flap and secure with tape.
Step 9: Assemble
Slide the cap onto the catapult arm and secure with tape
Step 10: Attach Base
Secure the base of the catapult to a solid surface (i.e. a table top or piece of heavy cardboard) using tape.
Step 11: Fire!
Ball up some of the paper scraps and place them in the seat created by the cap. Press down on the catapult arm and launch your paper ball!