LINKAGES: CRANK TOY ACTION MECHANISMS AT WORK (& PL AY )

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1 LINKAGES: CRANK TOY ACTION MECHANISMS AT WORK (& PL AY ) Cam toys convert rotational motion into linear motion. This simple machine is a great project that provides an entrance to mechanical engineering, and can integrate with a laser cutter and 3D printer to go from simple to spectacular. The D.I.Wire makes it possible to create a working crank and cam system all in one piece, so you can spend more time on the creative process. This makes crank toys ideal intermediate-level projects that put imagination in motion. SKILLS Intermediate bending Fabrication Designing Materials shot PROJECT FILES: Crank_toy_wire, Crank_toy_boxParts ENGINEERING MATERIALS PROJECT OVERVIEW Paper & drawing tools Needle nose pliers Wire cutters Scissors & Tape 1/4 thick acrylic sheet (3 x3 squares, 2 per box) SETUP: 15 min. IDEATION: ~15 min. BENDING: 1 min. per crank shaft HOUSING & PARTS: ~25 min. per toy* FULL ASSEMBLY: ~10 min. TOTAL BUILD TIME: ~ 1.25 hour Clear plastic foldable box, 3 x3 x3 (order online, or build your own) Grommets can be purchased on the web: PROTOTYPING 1/8 diameter wire, ~14 per crank 1/16 diameter wire, ~24 per toy Rubber grommets Lighter (optional) This project can be broken into 2 or 3 shorter sessions. *Add time if you don t have a laser cutter. DIWire@

2 SETUP, DESIGNING AND PLANNING Gather your materials. It s a good idea to plan ahead for storing in-progress projects if you don t have time to work all the way through in one sitting. This project assumes you have gone through the basics of using the DIWire. 1. Pre-cutting wire down to a managable length is ok, just remember that this will become a design constraint-- you ll need about 6 more wire than the total of your design s vector length to allow the feed wheels enough to hold onto. Sketch out ideas for the moving parts: get creative! DIGITAL FABRICATION: LASER CUTTING & BENDING 2. Download the file for the squares that hold the crank. Cut one of each side piece per crank toy. The acrylic should be at least 1/4 thick to provide stability for the box and the crank action. You can cut thinner material and stack it to a suitable thickness, too. DIWire@ 3. Download the crank file and open it in Wireware. Bend out the crank, being careful to keep the angles lined up for smooth crank action. Make sure not to cut the crank too short! 4. Slip the grommets onto the crank. Wiggle them until they are in the correct places for the pushers. If you don t have grommets, you can use skinny rubber bands on either side of the pusher wires to hold them in position.

3 THE HOUSING 5. Search for these boxes online at Amazon: Clear Plastic PVC Party Favor Boxes sold by Durapak or other sellers. You can also create free custom box files for the laser at just make sure you adjust your crank files to fit, and add the holes for the cranks to your new box files. 6. Assemble the plastic box by creasing and folding it, using a little tape to secure it temporarily if necessary. There are many alternative options for building the box that will hold the toy together. You can make your own box out of any sturdy material, from thick cardboard to wood. Using a pre-made box is recommended to save time and make fabrication easier. The box needs to be able to open on the top and sides for assembly, though. BOX REQUIREMENTS: Box dimensions for this project: 3 H x 3 W x 3 D (outer measurements) Remember that thicker walls will affect what will fit inside, you may need to adjust your crank accordingly. You can do that in Wireware or your vector art software. Box must be sturdy enough to keep the crank in place during turning. MARKING FOR HOLES Make marks in the center of both sides of the box where the ends of the crank will go. Mark the top, too. If you don t have a transparent box (or a lasercutter), you can draw lines connecting opposite corners to find the center of the sides. DIWire@

4 PUSHERS AND HOLES We like using the clear plastic box because it s easy to make the holes and get the mechanism in. If you made your own box, you will need to make sure your holes are all in the correct places and assemble it around the mechanism. If you don t want to use open flame in your space, you can use a screw or punch to poke the holes in the plastic box. 7. Use the needlenose pliers to bend rounded hooks that will loop onto the crank. Make them big enough to go all the way around the grommets. 10. Attach the pushers onto the crank. Be careful not to pinch the pushers onto the grommets too tightly, or they will not allow the crank to turn smoothly. Use the pliers to adjust the tightness Use a lighter to heat the end of a pusher. It does not need to be red hot, just hot enough to melt through 2 layers of plastic. 11. Stick the pushers up through the holes in the top of the box. Put the stationary end of the crank into the acrylic side with one hole and slide it into place. Poke through the top and inner flaps of the box with the heated pusher wire where you marked with the marker. Also poke the holes in the sides for the crank. 12. Flex the box a bit and fit the handle through the hole in the other side of the box so it sticks out. Then slide the slotted acrylic side up under the handle.

5 FINISHING ASSEMBLY After getting the acrylic sides into place, close up the bottom of the box. You can glue the acrylic to the sides of the box (super glue works well) for a more rigid structure. Clip off the pushers to the length that you want for your design TIP: Rub ends of wire against sandpaper taped to the table to take off sharp points made by the cutters! ATTACHING THE DESIGN The design you choose will determine how you attach the moving parts to the pushers. Other ways to attach pieces to the pushers include poking the pushers into slices of cork (attach anything to the cork) or winding thin, flexible wire or pipe-cleaners onto the pushers. You can drill into small wood pieces, or even 3D print custom shapes, too Cut out the design. This is a great place to get creative. Allow for flopping or springy action, think about using the whole length of the pusher, or creating a scene in motion. Attach the tape to the wire and the paper. 16. When all the pieces are attached, give it a few test turns. Make sure all the pieces are well-attached. DIWire@ 18.

6 CRANKING IT UP A LEVEL: MORE ADVANCED CRANK TOYS Making more complex mechanisms is no problem with digital fabrication. Crank toys are part of the traditional art of automata, as well as a great introduction to mechanical engineering. TIPS: Rotate the wire during bends for a 2.5D twist Add 3D printed elements Connect the pieces with joints, linkages, or springs for complex motion Connect the crank to a motor Rolling crank toy by Alexander Calder (the axle acts as the crank) DIWire@