HOW TO CREATE a MOVING CREATURE

A DC motor or direct current motor is an electrical machine that transforms electrical energy into mechanical energy by creating a magnetic field that is powered by direct current. When a DC motor is powered, a magnetic field is created in its stator. The field attracts and repels magnets on the rotor; this causes the rotor to rotate. To keep the rotor continually rotating, the commutator that is attached to brushes connected to the power source supply current to the motors wire windings. The created magnetic field is in the direction of the radii of the armature. The magnetic field enters the armature from the North pole side of the field coil and exits'' the armature from the field coil’s South pole side. 

When it comes to starting and regulating speed, brushed DC motors have a good performance. The torque density is relatively high for these motors. A Direct Current motor runs smoothly and the range of speed regulation is wide. The overload capability is strong and the electromagnetic interference is small. A disadvantage of the DC motor is the structure. There is a sliding contact between the commutator and the brush. This causes sparks and mechanical wear. Direct Current motors have relatively short life expectancy because of this and the motor has high maintenance cost. It also raises reliability concerns.

· A pair of pincers

· 3D printer (We use a Fused Filament 3D Printer, the module is called Creality CR - 10S)

· Glue (Hot silicone gun)

Electronic Components

· DC Motor 5v 150mA (We use a Faulhaber Type Direct Current Motor | Engine-165).

· Battery Holder Snap

· Battery holder (One for two AA batteries)

Softwares

· Tinkercad 3D Designs

· Ultimaker Cura 3D (for 3D Printing)

Items

· PLA 1.0 mm (3D printing filament)

· 2x AA batteries

· 2 Silicone bars (for silicone gun)

We start by making a 3D model of the DC Motor, including the battery holder using Tinkercad 3D Designs. The idea was that we use the model and use it as a template to visualize the final design. Also we create the enclosure for the electronic components so then we can add the parts that will give shape to the creature. An advantage is that the enclosure will keep all fixed and provide a better stability to the electronic components

After we discuss, we conclude that our creature is going to be a gray wolf. So on the design we choose to use this kind of color for all the body, but that will not be the color that was going to be printed, this is just to have an idea.

Once we choose the color of the body of our design we proceed with the head by adding a sphere on top of it and we join them, so it can be in position. On the top of the head we build the ears, for that we use a different figure, a cone with no points. We modified the shape of the figure so the ears could have shape. After that we began making the legs and we decided to use cones because it was better so he can move once is done. 

Once the head, ears and legs are ready, we begin by making the face and the tail of our creature. We start first for the head, we first thought of using a cone to make because we want to make the shape of the mouth, but we realized that it was not going to look well, so for that we add a cube with no points in the corners and the we add the cone and it look good. For the tail since the beginning we were not sure how to build it and we started using parallelograms but it was looking like stairs, until we found that we could make our own shape so we did it. After finishing it we added at the back of the creature and be sure that the pieces were together.

The final thing that we needed was to make the design the counterweight, for that we decided to use a parallelogram and then we needed to make the hole to put it in the DC motor. Since the beginning we thought that we could make it ourselves but we realize that we need to make it. We didn’t know how but after trying we found how to do it by adding a cylinder, making it transparent and joining the pieces together to make the hole. We need to be sure that it was in the right place and it fits and we were right. We definitely finished making the design of our creature.

Once we got satisfied with our design, we were ready to print. But first we select and take out the DC motor and the battery holder. When we finish, we access the export menu, and select .stl format which is the most common format for 3D printing.

Once we were done and sure that it was ready, we began using the 3D printer and checked on Ultimaker cura how long it would take to print. 

Our print parameter were:

· Material: PLA+

· Nozzle size: 1.0 mm

· Layer quality height: 0.1 mm

· Wall line count: 2

· Wall Thickness: 0.8 mm

· Horizontal expansion: - 0.01 mm

· Top / Bottom Thickness: 1.0 mm

· Top / Bottom Layers: 10

· Infill density and pattern: 20% triangle patterns

· Printing Temperature: 200 ºC

· Build Plate Temperature: 60 ºC

· Print Speed: 70 mm/s

· Build Plate Adhesion Type: Brim

When the printer finish printing the design, we the pincers to take out the remains and supports. We need to them carefully just to be sure that we don't take something that we don't want and take risk of creature loose shape.

1 . Once it finished printing what we did first was begin painting our creature with gray before adding the rest of the pieces on it. We use acrylic paint and a mixture black and white to make the color gray.

2 . After painting with gray and letting it dry we use a dark blue to make the shapes around the creature and make it look good.

1 . When the paint dries we proceed adding the pieces. We add the wires from the battery adapter to the DC motor terminals.

2 . The next thing we do is pass the strand of the wire through the terminal ring (of the DC motor) and wrap the wire around itself to form a knot. We connected the red wire to the terminal marked with the same color, just in case that it wasn’t going to work.

3 . Once the  both wires were connected to the DC motor terminals, we carefully coiled the cable to finish.

4 . Using a hot silicone gun, we glue the motor on top of the battery holder and Make sure that the motor pin is on the outside.

5 . Then we insert the counterweight into the DC motor pin and tighten it with hot silicone to make sure that it still holds.

6 . When the glue dried and made sure that the pieces were in position, well fastened and firm,  we added the batteries to the battery holder. But we still haven't connected the battery to the snap holder yet.

7 . We first make sure that the electronic components fit inside the enclosure that we printed in 3D.

8 . Once everything is ready and prepared to move, we connect the battery holder snap and we test our design to see if it works.

When everything went well and the creature worked at the first time it began to move! The way it works is that when you connect the cables to the battery in the behind part, the counterweight in the DC motor began to spin rapidly and then once we put it in the floor or table or whatever solid surface, it was really moving because since the electricity is powering it up the dc motor, the counterweight spin and that makes the creature moves.