Picture of Mechanical Hand

Students will make a simple mechanical hand with a trigger connected to a hinge. Once complete, students can test the ability of their hand by trying to pick up as many straws as possible. Extra class time (and there should be plenty!) can be devoted to further testing and redesigning to make the best mechanical hand possible!

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Step 1: Materials

For this design, you will need:
(and extra for redesigning)

15 Craft sticks
Craft cubes
Round cube beads
Part of 1 Straw
2 Skewers
2 Rubberbands
Hot glue

And a box of straws for the challenge!

Step 2: Build the hinge

Picture of Build the hinge
Cut two 1/2-inch pieces of straw. Wrap tape around the end of a skewer and thread the round cube beads and the straw pieces onto it as shown. Wrap tape around the other side and cut off the excess. 

The straw pieces act as spacers to prevent the fingers from colliding.

Step 3: Make the fingers

Picture of Make the fingers
Create the center finger as shown in the picture. The half-sticks are glued onto the side of the cube at a 45-degree angle.

The two other fingers are built similarly on either side of the center finger. Make sure that the half-sticks on the outside fingers are glued on at an angle that is inverse to the center finger.

On the 'back' of the hand, glue a half-stick to the two outside fingers. These two fingers will be actuated at the same time.

Step 4: Make the arm

Picture of Make the arm
The arm is an extension of the center finger. Sticks are glued together with at least 1-inch of overlap to ensure a nice strong bond. The arm can be any length, but longer than 6 or 7 sticks is not recommended because it is more difficult to lift objects that are further away from your body. The arm also may not be able to support it's own weight if it is extremely long.

Once the arm length is determined, add a handle and a thumb rest at the end. The handle and thumb rest that are pictured are very minimal - there is a lot of room for innovation and customization.
ijazzahir24 days ago

fantastic idea...its quite helpful especially for the elderly people, so thumps up..!!

_makerbot_1 month ago

does this actually pick things up? Is it a lever?

ericesquivelbr made it!1 year ago

It was great to do it, and I made one only enhacement, that I took a picture. Thank you... I have a lot of fun...

WYE_Lance (author)  ericesquivelbr1 year ago
Wow, this is awesome! Thanks for sharing - it's really cool to see others actually make use of these project plans :)
mohesh1 year ago

extremely awesome

TTSS1 year ago

Simply Wonderful.

That's awesome

Awesome! This would work great for a puppet hand :D thanks for sharing!

rimar20001 year ago

Good work! Maybe you could add a video.

So great!! Thanks for posting.