Simple Animatronic (robotic Hand) Made of Chain

This is very similar to:

https://www.instructables.com/id/Simple-Animatronics-robotic-hand/

I was originally going to build this as the link recommended - but I hate glue, tape and plastic. I want it welded/brazed/bolted together so I opted for what you see in the picture.

Took quite a few tips from the Mythbuster’s episode – (in hindsight not enough as it turns out)

I had the materials laying around the garage so I decided to see what I could come up with. I spent a couple of hours after work in the garage over a few nights & put it together. Originally I was planning on making this a proof of concept and doing a cleaner version with more detailed instructions but too many things going on so this is the best it’s going to get.

Components

Sheet steel for the hand

# 50 chain for the fingers

Copper tubing for the cable guides

Steel cable for the ‘tendons’

½ square steel for the back frame

1” tubing for the grip & finger pulling rings.

3/16 bungee cord for more 'tendons'

3/16 collars to retain the cable (from any decent hobby store for RC planes)

1/8 steel rod for the knuckle stops

Small washers & bailing wire

Tools needed

Weld pack 100 mig welder

Gas torch for soldering the copper guides to the steel

Some tools to cut & grind the steel – (band saw, sheet metal sheers, angle grinder, belt sander, etc)

NOTE #1

If you notice in the Mythbuster video & on my hand I use the 1/8 steel rod on top of the fingers as ‘stops’ to keep the fingers from flexing backwards. You have to watch the Mythbuster video quite a few times to catch this. Also the mythbusters video used a ‘C’ shaped piece of material for this. I didn’t’ and this caused me some grief because I wasn’t able to thread the bungee cord under the guides witihout binding. Something that they did in the video and I didn't catch the first time around.

NOTE #2

With this configuration you cannot have more than two joints move. That’s just how it works. On the longer fingers I originally tried this but had to not use one of the bends/indexes in the fingers. Again in the video you will notice just two joints move on any finger. The thumb & small finger actually work the best. If I were to make another one all of the fingers would have two joints.

NOTE #3

Friction is your enemy. Even with a short a pull as this is, minimize any binding and try to make the smoothest straightest guide for the cables as you can.

NOTE #4

The rings for the fingers were cut from some steel tubing. They are VERY uncomfortable on the fingers. I would suggest buying some steel rings to do the job instead.

NOTE #5

I retained the bungee in the tip of the fingers by threading it through a washer and used a bailing wire to retain it. Using the 3/16 collars is a cleaner idea. Also, dip/coat the bungee ends/tips in super glue to harden them. Works better for the collars to bite on for retention.

NOTE #6

I actually soldiered the copper tube to the steel. I could of silver solder it but soldering it worked fine.

Welding the 1/8 inch rod to #50 chain with a MIG welder is kind of messy.

Also there are only 4 rings. I tied the thumb & forefinger together. I couldn't make 5 cable guides fit.