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Robotic Hand

by embeddedjunkie, published

Robotic Hand by embeddedjunkie Apr 20, 2010

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Description

I would like to create this using a 3d printer. Dental rubber bands for braces act as tendons and hold the hand in a rigid state. When strings are pulled corresponding joints will fold, making the fingers open and close. I plan to have servo motors pull and release the strings.

**Here is a video of an earlier revision:**
youtube.com/watch?v=fKrzORMTyOE

**A crude prototype of the concept made from tubing, rubberbands, and zip ties:**
youtube.com/watch?v=_mID_RQ7qIs

**Testing of the "controller" glove. Only a single flex sensor installed:**
youtube.com/watch?v=OmnV2m10Eyk

**Original inspiration for this project is from:**
sciencetoymaker.org/robothand/assembl.html

**Video of the Printed Robot Hand in action:**
youtube.com/watch?v=WPuke73UgL4

**Flickr Set:**
flic.kr/s/aHsjvC1JYr

Recent Comments

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This is an excellent design, and it has great potential.

Don't you have an extra digit on the thumb?

Why are you building it from cubes, with 3D printing you can make nice and round finger tips. That would be more natural. Is it a modeling restriction?

How many motors are you planning? One for each finger and two for the thumb?

A hand is a tricky thing, the two joints (counting from the tip) operate together, but the third is almost independent (that is a minimum of two motors per finger)
The bearings are intended to reduce friction at the joints. But I will have to print the full model to decide if they are actually needed.

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License

Robotic Hand by embeddedjunkie is licensed under the Creative Commons - Attribution license.

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Instructions

The model was scaled by a factor of 1.10 to compensate for shrinkage. The thumb base part had to be cut in two pieces to address a design error issue. Loctite blue was used to prevent the screws/hex nuts from falling out. I ran out of metal bearings, so I had to print a temporary replacement part. The "hook" part is used to tether the fishing line to the tip of the finger. Then "ring" is used to ease the model manipulation. Epoxy was used to glue parts and re-enforce weak points.
This is an excellent design, and it has great potential.

Don't you have an extra digit on the thumb?

Why are you building it from cubes, with 3D printing you can make nice and round finger tips. That would be more natural. Is it a modeling restriction?

How many motors are you planning? One for each finger and two for the thumb?

A hand is a tricky thing, the two joints (counting from the tip) operate together, but the third is almost independent (that is a minimum of two motors per finger)
may use this model as a beggining point for a hand prosthesisi??
may use this model as a beggining point for a hand prosthesisi??
may use this model as a beggining point for a hand prosthesisi??
Where do the ball bearing come into play?
The bearings are intended to reduce friction at the joints. But I will have to print the full model to decide if they are actually needed.
What size screws and nuts does this need? I'm printing one soon and want to have parts ready when it's done. :D
The screws/nuts/bearings I will use I have left over from a robotics kit. I just found my lost calipers and I'll get those measurements in the next few days.
Have you managed to have one printed yet?
I just got news that my Thing-O-Matic 3D printer I purchased back in September has shipped. I will begin the printing and refining process soon!!! :-D
Do you have the files for each individual section? Awesome design too! work perfectly with some muscle wire.
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