Sunday, April 21, 2013

Skeleton Hands

Skeleton Hand

Skeleton Hand Tutorial

I had an idea about a year ago to make a fully articulated, poseable skeleton hand.  I thought about it, did a prototype of a bone, thought about it a bit more, saved some parts and thought about it a bit more.  I finally created a prototype last week and felt gratified that it worked out well so I made it's brother last night.  This time I captured the whole process in photos.  Here is the odyssey.

One of the first steps in any project is the research.  I wished to have my hands be as accurate as possible, or at least as credible as possible.  I started with which is a haunt site with some really cool bone proportion calculators.  I also researched hand proportions and found the following, from  I added a few of my own lines and numbers.

Hand proportions diagram

The Skeleton of the Skeleton
I have crafted with clothes hangers for many years.  They are predictable.  I know what they can do and what they cannot do.  I chose clothes hangers to be the superstructure for the skeleton hands.  The toughest part about the superstructure was to design the wire placement to accommodate the carpals, the meta-carpals and phalanges. 

I printed several hands from the Zombietronix page and developed a wire map for the skeleton hand. 

Wire #1 diagram

Wire #2 diagram

Wire #3 diagram

Wire #4 diagram

Mini-wires diagram

The superstructure is made from 3 heavy guage wire coat hangers with the top cut off and straightened.  The next time I make these I will use non-coated coat hangers.  The rubberized coating got in the way sometimes and I had to strip it in places to get the bones to fit.

Cutting off the tops

No top


The next step is to bend the wires and begin attaching them to one another.  This is done entirely by bending.  No external fastener or adhesive is used in this process.  The parts are bent according to the drawings.  These can be made as large or as small as you wish, within reason.  I made my hands about the size of an NBA player.  They're scarier that way. 

The wires that make up the thumb and the middle digit extend to become the radius and ulna bones.  Don't cut them to length until you know how much of the arm you need for your project.  Cut them to length at the end of the project.

To attach the wires to each other, bend small circles with long nose pliers about the diameter of the wire where the wires would intersect on the drawing.  It's important to note that each circle twist takes about 3/4 of an inch of wire, so you must add that much length times how many twists you need for each wire.  That distance stays constant no matter if you are making small hands or large ones.

The thumb bend

Bending the loop

The loop

The middle digit wire inserted in the loop

The second loop around the first loop

The forefinger and the pinky finger wire

The loops.  Next time I'll make these loops going opposite directions, one vertical the other horizontal

More of the forefinger and pinky finger wire with loops

The next time I make this project I will make one of the loop bends on wire #3 vertical instead of both of them being horizontal.  I believe it will make a more stable platform.  As it was, when the final project was done, it was plenty stable.  It would just make it more stable in process.

Before you assemble any more of the armature, you need to create and install some of the carpal bones.  This part of the process is part superstructure and part finish work. 

The carpal bones are made from different size wooden beads with the handles of milk jugs melted onto them with a heat gun.  Make sure you get beads with big enough holes to string on wire coat hangers.

This project takes a lot of milk jugs.  You will need to save them up for awhile until you have enough.  Better yet, have all your sympathetic neighbors and relatives save them for you.  When I get a milk jug, I rinse it and immediately cut off the handle and recycle the rest.  No sense having a ton of milk jugs hanging around.  I store the handles in a box or bucket and build them up until I have enough.  Pretty painless actually.

The humble milk jug

Cutting the handle off

Melting part of the handle to a wooden bead with a heat gun

The gnarly carpal

The first carpal installed

More carpals.  Note the wire from the ring finger wraps around the wire for the middle finger

I'm not as concerned with the carpals being exactly anatomically accurate.  I just need some mass down there that looks kind of legitimate.  The meta-carpals and phalanges are what are going to give this project it's credibility.

When I put this together, I realized I had missed a bead, and so rather than taking it apart and putting it all together again, I added the naked bead on the lower wire as seen above and cut a section of milk jug out, then cut up the inner seam.  Then I wrapped it around not only the bead but also the upper wire.  When the milk jug gets to temp, it becomes transparent and sticky.  I like to have something to poke at it with to move it around when it is in that state.  In this case I used a modified seafood fork.  You can also scab sections of milk jug in areas and heat gun them in place.

Cutting along the inner seam of the milk jug.  (The pink handled scissors belong to my wife)

Wrapping the cut jug handle around the bead and the wire

Heat gunning it to death

The scab

The Bones
Making the bones is pretty simple really.  It's nothing more than heat shrinking the polyethylene plastic from the milk jug around a couple of beads.

I made a jig out of an intact hanger where I straightened the hook part out, then made a stand with the rest of it.  You can make a jig however you wish, I had a hanger on hand, that's what I used.

This is a good time to talk about the size of beads to use in the fingers.  As I look at the joints in my own hand, I see that some of the knuckles are larger than others, some of the joints are larger than others.  This is true from end to end of individual fingers and it is true from finger to finger. 

I put together a string of beads to show the graduation pattern that worked for me.

Graduation pattern for the beads.  The meta-carpal begins on the left and the small bead at the end is the end of the phalange

To make individual bones for the meta-carpals and all but the final stage of the phalanges, take a bead and place it on the jig.  Sleeve a section of milk jug handle over the bead and then add the second bead.  Understand that the plastic will shrink when heat is applied, so cut the milk jug handle longer than it needs to be.  The length of the plastic is something that has to be figured out by trial and error, unfortunately.

When applying the heat, first crimp one end of the bead, then the other.  After that apply heat as evenly as possible along the length of the bone.  I use a seafood fork to move the bone around on the jig.  The plastic will turn transparent when it reaches temperature and will begin to sink in in the middle of the bone.  Gravity also works on the semi-molten plastic and it will begin to deform.  At this point, remove the heat and grasp the end of the bead with the long nosed pliers and hold the other end in place with the seafood fork and pull to the desired length.  When the plastic turns white again, it has become rigid and can be moved and placed.  I'm impatient, so I usually blow on the plastic to try to cool it faster.  I don't know if it actually works, but it makes me feel better so I do it.

Placing the first bead

Trimming the milk jug handle

Placing the milk jug handle

Placing the second bead

Crimping the end with the heat gun, note the seafood fork

Crimping the other end with the heat gun and the seafood fork

Heating the middle, note how it's becoming transparent

Becoming transparent and sagging



The jig is really important, by the way because you need to line up the holes in the beads in order to sleeve them onto the phalange wires.  Which is the next step, by the way.

As you sleeve your bones onto the wires, pay attention to the length of the fingers.  The middle digit is the longest etc...  I paid attention to that moreso on the first hand and less so on the second hand.  The second hand still works, but it isn't as elegant as the first.  Keep that in mind as you bead the wires.  This really is just a beading project actually.

Start with the meta-carpals, then the first two joints of the phalanges.

Meta-carpals installed

First row of phalange joints installed

Second row of phalange joints installed

The last joint is also the device where the beading is held into place.  Take a small bead, place it on the end of the wire, then cut off the excess wire with the side-cut on the pliers.  Leave enough to bend over.  This will lock the bones on the end of the wire and it also gives the foundation for the final bones of the phalanges.

Take a small section of milk jug handle and place on the bead.  Heat crimp the plastic to the bead, then move the heat to the rest of the plastic.  When it becomes transparent, begin shaping and pressing the end of the plastic around the end of the wire.  Try to force some of the plastic inside the hook on the wire before it hardens.

Small bead

Trimming the wire

Bent wire

On the jig

Jug handle on the bead


Crimped and finished

Fill in the remaining holes in the wrist, the carpals with more covered beads and a strand of floral wire.  I don't have any photos of this step, but it's quite simple really.  Just fill in the holes.

I purchased a ten ounce package of wooden beads from Wal-Mart for $4.97.  I did a rough count and determined that within forty beads or so there were about 300 pieces.  That comes out to about 1.66 cents per bead.  This project takes about forty beads so it comes out to about 67 cents of total beadage per hand. 

I purchased a package of floral wire for $1.49.  It had 20 pieces.  I used one strand per hand.  That comes to 8 cents a hand for wire.  That comes to 75 cents out of pocket per hand.  Not bad eh? 

Wal-Mart Beads for $4.97

Floral wire from a craft store for $1.49

A pair of hands

This was a fun project to create.  Know that polyethylene plastic is very difficult to paint.  It rejects almost all paint.  There is a spray paint by Krylon especially formulated for painting on plastics.  I would recommend using that.

I have about four hours total time in these two hands.  I imagine if I made more of them I could knock that back to one hour per hand.

1 comment:

  1. Thanks for the excellent and detailed tutorial. Going to try and make these soon. Just curious, how did you finish (cover) them and what did you use them for (with)? Thanks again.