How I Made a Mechanical Hand. No Electricity and All From Junk.

Alright so this is right about going to be my first complete project, hope it works perfectly in the end. If you are reading this with hope of trying it out, well do not start till you have completed this Instructable. If not you will only make the same mistakes I did. It's a mechanical arm you can control with yours. It's is all from old and waste materials and does not run on electricity. So the supplies

1. Wood ( that can be easily carved) or any other material that seem suitable
2. Old gloves
3.Razor, ruler, saw, glue (super glue), gum ( top bund) and pins
4. Fishing line
5. Tape
6. Rubber bands
7. Pins
8. Flexible tubes ( I just used old wires and removed the copper. It's not very efficient)
9. Empty biro pipes

So after cutting each section I started carving the end of each piece to make the facets for the joint. For the joint to work one had to be carved so as to fit in another which is also carved so that with a pin, one part can move on the other.

First I started by carving each part as if it was going to be a skeleton. Each portion of the finger (3) and the part that makes the palm. But before that I took the old piece of wood I got from my sister's room and split it into four sections. Then I cut them to the required length and started carving. To get the lengths I used the measurements i got from my own hand. So I am not an expert in carving but the only thing I learnt was to cut along the grains ( or something like that). As can be seen in the picture I only used a saw and a razor blade

So the pin sort of acts as a fulcrum. It is what joins the different sections of the finger and ensures it can turn. In my design I made the upper section free on the pins and made the pin stationary. After joining all the sections on each finger together I then used the pins to join the fingers together to make it more of a hand. Before adding the thumb I cut an angle out of it.

I carved out some flat pieces of wood and glued them to where I chose to be the back of the hand so as to hold everything together. There after I glue every other thing in place including the pins.

So I decided to add more joints. I carved out more parts. I think the picture explains almost everything. For the ability to turn round I had to put an an extra section in between the wrist and elbow. It's a piece of wood with an arc carved under so that the head of the pin can rotate freely. the edge of the pin then goes in the upper section and everything is glued together.

Now I checked to ensure everything moves smoothly. The easier everything moves the better, unless you plan on just making the skeleton. Which to me is still a pretty good ending

OK from here is where things start getting a bit more difficult. I cut some rubber bands and glued them across the joints so that the parts that bend can be elastic. There after I made a small hole on each section close to their base. Then I put the wires in. This is just to ensure the wire does not just pull off when in use.
Next I bore a hole straight through each section ( except the first) large enough to fit a biro pipe. Next I cut a biro pipe into the hole and pass the string through. The next thing I did is a bit unnecessary. I cut another pipe and glued it in to guard the string. This part is a bit hard to see in the picture, sorry about that.
Please note that the sting in enters the wood from the front of the hand not the back.

At this point I noticed that not all the joints could not just so easily take a strip of rubber or two to be elastic.
So I kept working and looking for a way. Eventually I came up with the following:
1. Across the elbow I placed several strips of rubber across the joint and made its resting downwards with gravity
2. Across the wrist I put four strips at the back and at the front two on each edge instead of the centre making the centre position its rest ( so it can bend back and forth)
3. For the turning I made a groove for two strings to be able to go round it. One that then goes down through a pipe downwards to some strips glued stationary. The palm facing up became the rest position. The other string passes through another pipe on the opposite side to be used later.

First I made what is in the first pic. It is what holds the hand to the base and support.
The flexible tubes used are from old wires. I got the wires and pulled the copper out of it. I discovered that wires with one thread were better. The entire process was stressful.

The work of the flexible tube is to guard the wire and ensure that force would equal tension not change in position. As in if I pull without the wire or something to guard the wire the pull would not lead to any motion.
You might notice from the diagram that the first upper two sets of tubes are bent to the sides instead of straight back. This is because I discovered that the less complex the better. And that when I formally made the tubes go straight down the tubes would have to move at certain points and trying to correct that was getting too complex.
Sadly this affected the efficiency of the whole thing.

So after placing the tubes in place, next is to arrange them in order to respect other joints.
1. I continued adjusting the tubes from the fingers until the other finger joints could move freely
2. I carved two wedges ( like right angle triangles and used it to pass the tubes from the wrist across the part that rotates. In such a way the tubes aren't touching the pipes
3. The then curved the tubes from the fingers and glued them together in sets then glued them under the wooden structure I earlier made.