Simple Animatronic (robotic hand) made of Chain

This is very similar to:

http://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)

http://www.youtube.com/watch?gl=GB&hl=en-GB&v=phQcTjnmTcw

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. 

 

 

 

 

 

 

Comments

[TheGuerrillaAlchemist]

Could it be possible to stretch the fingers out like 2 feet or more? I want to make waving tentacles like this.

[r570sv]

You could and I think there may be an example of this as another instructable.

I wouldn't use chain to do it, I would use wooden dowels/tubing. You would have to weld every link of the chain in place. would be very heavy to try to hold up

[StiltGuyJoe]

wow, that is beautifully creepy... or creepily beautiful. whichever you prefer.

[cool herc]

Nice, but Stark was able to build this... in a cave... WITH SCRAPS!

[LeviMc]

Hey if i built this i would tweek it a little, what i would do is instead of bungy cords i would use some more cable and conect it to a trameline type spring , one spring of desent size like this would probebly be able to control all the fingers at the same time, it would greatly reduse friction.Also not a big deal if you inspect the hand before each use but if you dont the bungy cords will eventualy get frayed by the friction from the chain and snap whereas the spring wouldn't I really like the idea and think i will build mine out of smaller chain so i can put a glove on it making it more reilistic

[ModderXtrordanare]

Hate to break it to you, but Mythbusters didn't come up with it either.

[jaylove20]

there is a old toy just like that  you would wear it over your hand I forget the name of it

[gurusean]

Watching this video I kept thinking, " I'll Be Back ".

[dramioneforinfinity]

Very cool. I'll have 2 make this 4 skool. It would also b handy during cleaning my room.  :P

[XOIIO]

That spelling is making me cringe! Please use the spell check and full words at least.

[372jpeg]

Wow, it really works,everything i build never works.Great instructable.

[jefletch]

LOL, Sounds like me....

[Cammer]

This is a cool idea and seems to be a very strong and durable design, but one improvement that I immediately notice would be the addition of an opposable thumb.  I think that by increasing the angle that the thumb closes you would get a better grip on things with this device.

[mje]

 Simple and elegant! And easily adaptable to automated control. I'd suggest using bicycle cable and housing instead of the copper tubing- cheaper, and lower friction. 

[r570sv]

Good idea!  Makeing the stops for the cable wouldn't be too complcated either!

[Ststephen7]

 Very nice!!  After seeing that Mythbusters I had to make my own.  It was the first thing I made from steel, so it took me a while.  Here's a link to my youtube video..http://www.youtube.com/watch?v=lwubB9iBPlk

I used an air cylinder to move the fingers, and surgical tubing on the back of the fingers (after many failures with other products).

[r570sv]

VERY cool!  That's close to the one on the show.  very nice!!

[darth2o]

I had a plastic toy exactly like this when I was younger.

[golddigger1559]

it was for iron man wasnt it?

[Lithium Rain]

Very nice. Reminds me of Adam Savage's early "anamitronic" hand.

[Fred82664]

I think I remember that episode ????? it was the one that they tried to catch a arrow in flight ,,,???or was it the one they tried to catch a sward as it was in swing   

[r570sv]

I've included that mytybuster link in the top of my write up.

http://www.youtube.com/watch?gl=GB&hl=en-GB&v=phQcTjnmTcw

[Fred82664]

well I see that It was not the two I thought it was, but they did reuse it in other episodes. cool show any way !   

[erosser]

 Wow, amazing articulation!  Very nicely constructed--looks very durable.

One suggestion: you could use some rubberized tool grip and paint it on the "palm" for extra gripping.  Maybe then you could actually pick up and manipulate glasses and the like.

Also, did you consider welding the chain in place so they would bend more like real fingers?  Then again, I'm sure it's cooler when they bend in wild ways...:)

Again, nice job!

[r570sv]

Some of the links are actually welded in place.  Its kind of hard to see from the pictures. 

Also the 1/8 inch rods on top of the fingers prevent them from moving backward.

[merijnvw]

 very cool! Maybe you could've better placed the thumb more on an angle so it would be easier to grab things