Waving Arm

by 2025167 in Circuits > Arduino

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Waving Arm

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I made a waving arm using a stepper motor and PLA to create an arm design because originally, I wanted to make a flapping bird and have it fly in the air, but it was too ambitious with the resources and time I had, and then I thought of making a robot arm, but heavily simplified to only making it wave.

Supplies

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Stepper Motor (28BYJ-48 [12 volt])

Arduino Board

12 volt AA battery pack

Stepper Driver

USB-B cable

Computer

PLA

Adding the Base

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First, I made a sketch in Fusion 360 and extruded it to create a base for my arm. When making the rest of the design. The base was too small as it would fall over, so I had to extend the base to keep it balanced after step 4.

Adding the Neck and Humerus

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After making the original base, I added the neck with a hinge to attach the humerus parts. I used the extrude tool by having the hinge intersect to cut holes on both sides of the humerus. It also cuts through the neck, but the hinge is its own component, so it is like it never cut through it

Adding the Motor to the Humerus

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Using the stepper motor file attached to this instructable, I inserted it to the humerus. I created a hole by using the combine tool with target body being the humerus and tool body being the stepper motor with the cut operation. I used an offset face by a distance of -0.2 mm on side of the hole to make the motor fit in nicely without getting stuck and being too tight.

Attaching the Arm to the Stepper Motor

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I made a sketch of my arm, so that the stepper motor can rotate it. I positioned the arm to the stepper motor so that I can extrude the orange piece to the arm in order for the motor to rotate the arm. There is an offset of -0.1 mm.

Final Touches

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Once I started to 3D print my design, I noticed a few problems that I had to resolve. One issue was that I forgot to offset the holes on the humerus that the hinge cut, because it was too tight. Another issue that I had was that the base was too small, so as said in step 1, I extended it to keep the arm balanced. One last issue that I had was that the humerus with the motor would fall because of how heavy that side was, so I created some support to keep it balanced. (insert the images from my phone)

Using Arduino to Get the Motor to Rotate

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I set up Arduino where the 4 wires in the Arduino board go to the ULN2003 and there is also the stepper motor attached to the ULN2003. The blue wire goes back to the Arduino board to create a common ground to complete the circuit between the motor control and the Arduino board, and the battery pack. The red wire next to the blue wire goes to the black alligator clip and the red wire in the ULN2003 goes to the red alligatorbclip of the battery pack to link the power to the whole circuit. The diagram is a good reference to know how it should look like.

Coding the Stepper Motor

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This is the code that I used to make the stepper motor move. I have the code attached to this instructable.

Final Product

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