Developing nations leg

As part of my program we were assigned to create a prosthetic foot that could be used in nations where commercial prosthetic parts were unavailable. I got I to the project and expanded the scope ultimately making a bent knee device that someone who is able bodied could wear. This device could also be worn by an amputee who is very sensitive and cannot end bear at all or a patient who can't ambulate normally on a broken foot or ankle.

I was inspired by an article (http://www.instructables.com/id/Making-Blocks-out-of-HDPE-milk-jugs) on intructables which describes the process of "stewing" waste plastic, milk jugs and shopping bags, in cooking oil until mold-able and then press them into a block. I thought that these would be ubiquitous enough materials to suit my purposes while being robust and weather resistant. I wanted to have a grip surface on the plantar aspect of the foot so I pressed the plastic down onto a piece of old car tire with metal bolts and t-nuts attached to it for a mechanical grip between the plastic and tire. The author of the article suggested a press to squeeze the plastic into the mold and squeeze the oil out of the plastic. I probably should have stuck with a car jack type press but was reminded of a biomass briquette press I had read about. This press (http://home.fuse.net/engineering/ewb_project.htm) is used in places where firewood is scarce to produce briquettes from green waste and paper pulp. I figured if I could make it from scratch I would not need to argue for a source for car jacks or premade presses so I put one together. 

This assignment was presented to us almost two years ago so I have been kicking it around for a long time and got it in my head that I wanted to make a knee to go with my foot. I was talking to one of my professors (https://mobile.twitter.com/cyborgeek) and he has a knee design that he has been trying and refining over the year which he allowed me to use as a starting point. I had trouble with the bar linkages so I added plates to the outside of the knee. I used wood and metal but hope to replace the wood with presses plastic like the foot in future designs. 

Finally I needed an interface between the knee and the user so I made a socket which I made from 4 inch PVC which I cut and heat formed to make it the shape I wanted. I added velcro straps because of a final time contstraint but could replace them with leather or other types of straps. I lined the socket with felt used to cushion items while moving or shipping made from denim scraps. This gave some cushion and protected the wearer from the heads of the rivets used to attach the socket to the knee.

Some pictures:

I hope to make a few refinement to this design before moving to other projects. I would like to make the knee again with plastic instead of the wood. I would like to make the connection between the socket and knee more robust and I would like to add some more adjustability to the overall design to allow for static and dynamic alignment. The original assignment called for a cost of no more than $20 for the foot. This foot totaled $17 but could be made more cheaply. The entire device cost $48 not including the press to make the foot.

I would welcome questions or input about this project.