Carl v3 - Halloween 2012 - "Let's give Carl a hand!"

Carl and Me Last Halloween

Let me tell you!  You want kids to enjoy Halloween, just give them Play-Doh!  The tiny Play-Doh Party Pack cans were a huge hit last year.  (see last year's blog entry)

I would tell the kids they had to ask Carl "trick or treat" if they wanted something.  Carl would make some noise and then drp a Play-Doh can into the palm of his hand.  I had numerous kids look at me in amazement and ask, "Can I really have this?" 

Carl ended up giving out over 120 cans of Play-Doh that night.

So, for Halloween 2012 how am I going to top that?  Let's give Carl a hand!  Really!  If his right hand is giving out Play-Doh, let's have his left hand wave at the kids.

Here's my first test at just building a finger from PVC and one servo:

After 7 months of work testing variations of the first finger I ended up with a full hand:


I learned some important lessons.

- Fishing line loves to get tangled.  Just one line crossed over another will bring everything to a grinding halt.  That's the reason for the plastic tubing on the arm.  Running the control lines through the tubing keeps the lines from crossing and getting jammed up.

- There are two lines per finger in a push/pull configuration.  If you look closely near the servos you'll see an eyelet in behind each servo.  The line the close the finger loops through this rear eyelet effectively reversing the action of the servo.

- These are standard Futaba 3001 servos however they really aren't strong enough.  It would work much better with heavier duty servos.

- Solid copper wire makes really good hinges.  Each finger joint just has a single loop of solid copper wire through it and twisted closed to make a hinge for the joint.  Very simple and effective.

- PC Power Supplies (bottom right corner of video) are CHEAP!  I got this mini-ATX power supply from Tiger Direct for about $10.  It supplies lots of amps at both 5 & 12 vdc.  Great for operating the servos and the Arduino Uno computer.

- the Arduino UNO micro-controller can't be beat if you need an easy to program controller for a small number of servos.

And here's a video of Carl in action waving at the kid(s) and giving out Play-Doh: