Today, I am going to make a cardboard arm that actually moves! This is a simple project, inspired by someone else. This inspiration will be used to make my cardboard arm for a STEM project. So, how does the cardboard arm work? The strings that are being pulled shorten, therefore making the straws come closer to each other. The shrink and stretch of the strings move the fingers of the arm. Making it able to move and grab. If the straws are attached to the cardboard arm, it makes it functional. So, that now you kind of understand the concept of cardboard arms, now on to the making of it.
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Step 1: Materials
To do this project, you will need:
– A piece of large cardboard
– Clear pen barrels or clear straws
– Elastic bands
– Hot glue gun
Step 2: Cardboard Outline
- To begin with, try to draw the outline by pencil.
- The length of the cardboard should be around 60cm.
- The width should be around 12cm.
- Add indentures to the front part, making it 1cm deep, and 14 cm wide.
- It is really up to you to how you want to make the cardboard base. People have own shapes and sizes of arms, so the outline is up to you. Though try not to make it too short or too long, recommended length is 60cm.
- Once outline, cut it out with a pair of scissors, or better, use a steak knife. (steak knife are really good cardboard cutters.
Step 3: Fingers
- Then, Cutout cardboard fingers, these are the objects that are going to move.
- The fingers should be rectangular in shape.
- Fingers can be as long as 20 cm and as short as 10cm. 14cm is recommended for the length of the fingers.
- You should make 4 pieces although hands have five fingers,
- Once you have cut out the fingers make 5 - 5 - 4 cm folds
- When completed staple it to the main structure(cardboard outline)
- The first three fingers are stapled in the front, the last one, will be stapled to the side.
- Once stapled to the arm, move on to the next step.
Step 4: Mechanism (Straws & Strings)
- Cut small pieces of tubes, with straws, to make the structure for fingers.
- Cut around 2-4cm of straws.
- Once completed, utilize the hot glue to glue the tubes next to every fold of the fingers.
- In other words, between 5cm, 5cm, and 4cm.
- Also, add them to the main structure as well.
- The should be placed in front of the fingers if placed at the main structure.
- The tubes for the thumb should be placed in a slanted horizontal way.
- For every finger, slide the strings through the straw tubes glued earlier.
- There should be four strings. passing through each finger.
Step 5: The Frame
- To add the frame, that allows the cardboard to attach the real arm, you must build the sleeve with cardboard.
- The frame should be 20 cm, and height should be determined by the size of the arm.
- Cut out a square piece of cardboard.
- Fold it in half, to form a valley.
- The valley should be in triangle from when attached to the main structure.
- Cut out a rectangle through the two sides.
- Put your arm through to test whether it firmly grips you.
- If not, try to adjust.
- Then Hot glue it to the frame, nearer towards the opposite end of the fingers.
Step 6: Optional (motors)
- Add the motors by connecting the string with the Servo motors.
- Connect it to the battery.
- Add buttons to the motors.
- Put them all in a frame.
- Use copper wire to connect the string to the motors.
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