Waldo                                                                                      

wikipedia.org/Waldo

As a kid, I read Heinlein’s short story, Waldo and I've wanted to build robotic hands ever since. I had a bunch of junk laying around that I bodged together to make an Arduino controlled robotic hand that is designed to fill in the missing numerals on the newspaper Sudoku puzzle. (See previous posts for how the Sudoku solution was obtained.) 








 

Mustek scanner

Waldo’s base was made from a nonfunctioning Mustek flatbed scanner. I use the scanner’s 12V stepper motor, electronics and drive-train to move Waldo’s arm from side-to-side. I mounted a piece of whiteboard to the scanner top for a writing platform.





 

Rack&pinion mechanism

I used a rack–and-pinion mechanism from a discarded medical instrument to move Waldo’s arm from front-to-back. This step motor driven device was mounted onto the scanner’s drive train and required a support wheel riding on an adjustable rail. The arm traverses a 9 x 6 inch area of the writing platform in an (X,Y) fashion.

Waldo's hand

I made a mechanical hand that holds a gel pen refill. There are three degrees of movement actuated by small servo motors. Two of the servos can finely move the pen over a diamond shaped area of about a half inch across. This is used for the detail work of drawing the digits 1 through 9. The third servo can lift the pen off the paper.




 

Waldo nearly finished

A PVC lamp stand (and USB camera) is attached to a box-like scanner cover. I am really happy with the looks of the finished device!