One of my task was to redesign the fingers. Nathaniel and I liked the original finger shape more or less, but not the actual dimensions. We wanted the the thumb to have a different thickness than the other fingers so that it could pick up smaller objects. 

We had many struggles with this design because we wanted the fingers to do more presicion work, but also wanted to give someone the ability to still toss a ball around with their friends. 

Our first problem was that I did not design the finger around the other part that connects to the knuckle, so when I tried to put the finger and the other part together in a rhino model the hole that were supposed to line up to put the pin through did not line up. I basically had to redesign the finger several times to get it just right, because either the holes were too small to put the string through or many other basic careless interference mistakes.

Because we wanted two different sized fingers, we also had to create a whole other finger from scratch. We  wanted the thumb and the index finger to touch when you clamped we had to measure how long the index finger should be to be able to touch the tip of the thumb.

I learned to always model around pieces as to not mess up any measurments and to think methodically about which pieces to create first so that you did not have to work twice as hard to get the next pice done.

We had also found another problem with the original design of the RoboHand. We did not like how on all of struts there were two, and you had to put like ten pins on each side just to have that piece be pretty flimsy. So Nathaniel and I thought, why not just make it all one piece. The problem in our design for the knuckles though was that the knuckles were slanted, so when we printed the first prototype of the struts, it did not align right. We had to go back into Rhino and go and edit the struts to make one of the pieces longer. 

Another problem we had was the connector piece to the knuckles. This piece was not hard, but I just was not thinking when made it. I made this piece after the finger, which was the wrong choice, because the piece did not give the finger maximum angle to rotate. Also there was interference with the knuckles, and it gave it almost no angle to rotate. Eventually I made the right decision and modeled the connector piece around the knuckles and the fingers.

Using the open source RoboHand prosthetic as a basis for design, students re-envisioned the device to provide functionality beyond the capabilities of a traditional digit-based prosthetic. Students worked with the eNable online community which produces low-cost prosthetics to children for whom a standard prosthetic is cost-prohibitive and impractical due to growth. Students also worked with a local peer in need of such a prosthetic and are currently in the process of organizing a design charette matching users and young designers.

We put together a snap-together prosthetic hand that's designed to move, and started trying to understand the mechanisms inside and how they work. The hand can be downloaded from http://www.thingiverse.com/thing:92937 .

After examining and building the original RoboHand, Sam and I took notes of what needed significant improvements. The RoboHand seemed like a very rough design and was difficult to get working and adjusted the way we wanted it. Main problems that we found were that the original design was difficult to string up and adjust, it could really only grab larger objects, and it was a bit rickety. To solve these problems, we basically re-designed the entire hand.

Starting off with stringing it up, we did away with having to tie knots on the body of the hand. It was basically impossible to string up each finger perfectly. Some of them might have less range of motion, and others would bend all the way. Instead, we took ideas from the Violin. In order to tune a violin, you take out a rod, twist it to your desired setting, and ram it back in. It stays in the hole because the tunnel is tapered as well as the rod. We implemented this idea into our hand and now it is much easier to string it up and make fine adjustments to the fingers. It also looks extremely cool.

The knuckles also got a make over. The original RoboHand had a straight knuckle and didn't allow for a wide array of movement. By angling it, much like a human hand, we could have a wider range of movement and possible more grip. Unfortunately, this meant that we would have to change the side bars so the entire hand could rotate and still have parallel side bars. We also changed the position of the thumb to under the index finger which would make it more like a claw. This would make it easier to grab small objects. At first, we made a lot of mistakes. Our 3D models weren't closed polysurfaces, which became a huge waste of time and was extremely frustrating. But after making sure all of our objects were correct, we were finally able to print.

Sadly, after printing out all of our pieces, and finally getting the change to put it all together, we realized how many mistakes we really made. The pieces all had too tight of tolerances and would either not fit together, or have a lot of friction and not move freely. The only thing that really worked was our solution to stringing it up. It, for the most part, worked perfectly and would be a great design change for all of the other groups "hands".

We're printing 5 new fingers, each with a slot fitted for our pen attachment (or some other) and a new bridge to get rid of all the hot glue. We've removed the front part of the fingers and the rear bridge so we'll be able to add them in when they're finished.