Introduction: Low Cost PVC Prosthetic
In this instructable we will explain how we made a simple prosthetic leg for less than 15 dollars
This prosthetic consists out of 3 major parts.
The first part is an inner liner that is made out of layered fabric glued together with wood glue.
The second part consists out of a shaped PVC pipe
The last part consists out of a printed insert with a steel bolt.
This is not a replacement for a professionally made prosthetic but is an experiment meant to find alternatives for the prosthetic leg production in third world countries.
Step 1: Step 1: Mould
For this step we made a mould out of PU foam.
We used a 3D model of a real mould and took measurements. With this information i shaped a foam block until it corresponded with the measurement of the 3d model.
Step 2: Step 2: Insert
To give the bolt extra durability and strength we use an insert
This insert is 3D printed but could easily be replaced by some metal strips.
Once you have printed the insert its only a matter of placing the bold true the insert.
Step 3: Step 3: Inner Liner
The inner is made by coating strips of fabric in wood glue.
Then you layer the strips on the mould. you can protect your mold ba wrapping it in plastic foil.
Once you have layered about 4 layers you leave it the dry for a few hours.
When the outside of the first few layers is almost dry and still a bit tacky this is when you place the insert.
You simply position the insert into the wright position and use heat gun to shape it to fit the liner.
Once this is done you can continue with layering the fabric and wood glue for at least another four layers.
Ideally you want the thickness of the insert to be have about the circumference of the inside circumference of the inside of the PVC pipe you want to use. This will make everything stronger later on.
Step 4: Step 4: Outer Liner
The outer liner is made out of PVC tubing.
We use the inner liner for the mould.
The PVC pipe is heated in a simple oven once the PVC is flexible enough for the tube to fall into itself it is ready to be moulded.
At this point you can remove the PVC from the oven en simply push it over the inner lining. Once te PVC is in place you quench it in cold water.
This makes sure it will hold its shape and wont change while cooling.
Step 5: Step 5: PVC Shape
To give the connection extra strength but making sure the prostetic does not become to long we shape the lower end of the PVC shape.
This is simply done by cutting the PVC length wise in 6 pieces until 5 cm under where the inner liner stops (not including the bolt).
Once this is done we used a heat gun to make the PVC flexible and folding it into an overlapping pattern. this gives everything extra strength.
Step 6: Step 6: Final Assembly
For the final assembly it is just a matter of placing the inner lining in the PVC pipe and using a nut and washer to fasten everything together.
In the pictures you can see we used some plastic pieces. This is as a replacement because we did not have a nut that was large enough.
you could also use a peice of metal sheeting with a hole drilled into the middle.