Artistic visions for prosthetic design III - playing with instructions and materials

I started out being surprised by the visual attraction and emotional impact of a primarily artistic (rather than functional) prosthetic arm. I continued to walk in amazement for a while.

Then I tried a simple but very powerful design variation myself - my Red Hand Experiment that started with a mannequin hand that I had painted plain red using glossy acrylic paint. I loved it. I loved the idea of having come up with this myself, of having painted it myself, of having worked on constructing the wrist myself.

Thirdly I feel that I know best what's good for me in terms of artwork. I may be wrong, obviously - there are far better artists that can draft and showcase prosthetic designs. But they don't call me, they do not send me their prototypes, let me wear them, they don't see to it that their designs make it into production - nothing of that kind. Not until recently that is, when Dan started his business. Furthermore, prosthetic artwork is not insurance covered and so price plays a huge role. Otto Bock, Hosmer or TRS do not carry artistically enhanced prosthetic parts - and if they would, I probably could not pay for them.

And so one of the things I consider is doing it myself. Even if other people will never understand it - being able to creatively shape the way I can fill in my own missing part helps greatly to live with it. I find that working on my arm is good just to feel better about it. That creative process feels like a necessary part of healing to me.

So now seems like a good time to look at technical aspects.

Walk through introductions on how to build a prosthetic arm

Tools, mounting parts, check list

Working one-handedly, tools and how to fix or hold objects is a major issue. There are a number of tricks to this though.

A first rule is to first test the failure direction of a device. When my grip fails, when the mount fails - where will the parts go? Will they jam against the table or will little bits be scattered all over my face?

A second rule is to go slow and try out first. The more difficult a particular job is, the more time I spend trying it out first.

A third principle is to make sure I have extra material. With just one hand I find that I use up more material and that I may be what you'd call inefficient. That means to get more sandpaper, more paint, an extra model of a hand, more fabric - just so you have some reserve to play with.

A fourth principle is to make sure I have more than enough time. Twiddling around with tools means - as mentioned just previously - to test this and that, to approach cautiously and more and as all of that uses up time I try to make sure I am not under pressure.

A fifth principle is to make sure to not damage my stump, my hand, my prosthesis. This has a high priority.

And a sixth principle is to make sure you define a boundary, a limit. When will you stop? When will you accept defeat? When is the moment when you need someone to help?

Seven. A good idea is to draft a plan, to devise a strategy or to at least work towards something like that.

Trick eight. I use padding to hold an object between stump and my body. I use padding to protect an object that's screwed into a vice. I use padding to protect an object from an accidental fall. I use extra parts to hold my object in a certain position.

Shape of the arm and material

I realized that one way or another I'd have to start with some substrate. I used the 3D model of a mannequin's hand and tried to get a 3D rubber model from it but that turned out to be real expensive. At that moment, I may as well get that model to be chromed steel and contain the wrist lock mechanism. But 3D scanning and rapid prototyping is just one way to get a substrate - there are definitely other ways.

  • Preproduced commercial hands such as mannequin dummy hands or models for artists; that is what I did for my Red Hand Experiment. The mannequin hand was then filled using foam while embedding a foam anchor to link it to my wrist unit. They may not end up being more functional than a cosmetic prosthesis but they are - compared to medical supplies - dirt cheap.
  • Prosthetic arms or hands. Obviously, there is a number of prosthetic parts out in the market you could try to get and adapt to your own needs. If they are run down, worn out or discarded they could be affordable.
  • Sears CRAFTSMAN COMPUCARVE- this looks like it has huge potential for building parts oneself but this seems to be hard to get over here in Europe.

Painting it

One way to paint something is to get color and apply it, then experience what happens. I'm a real amateur and so this comes to me naturally. Another way is to very carefully plan the painting process. That is where professional knowhow comes in.

Sanding

The surface of the object then has to be prepared properly. Some people say that this is far more crucial than amateurs assume. Also, amateurs do not like to prepare surfaces properly. I remember slathering red thick silicone sealing on a hard glossy surface of my dummy hand. Of course I had just tried that out to see what would happen - but that silicone came off so fast it made my head spin. So: spot on correct!

The first recommendation is to get some fine sand paper (around 200 to 280 grit) and lovingly and carefully sandpaper the surface. Then very thoroughly clean it, it has to be sanded, clean and dry.

Transferring a pattern or shape

Painting

Royal Talens includes some interesting instructions with their product website. They sell acrylic paint as well as other materials such as glossy gel to increase reflectivity and elasticity of the paint:

Then, there are a number of good books about painting or airbrush painting:

List of technical skills to learn and to master

  • Process silicone to build liners
  • Work with plaster, cast, molds
  • Process epoxy and PET to build sockets
  • Include Rapid Prototyping to create mirrored 3D shapes
  • 3D wood work

Cite this article:
Wolf Schweitzer: Technical Below Elbow Amputee Issues - Artistic visions for prosthetic design III - playing with instructions and materials; published May 22, 2009, 11:46; URL: https://www.swisswuff.ch/tech/?p=176.

BibTeX: @MISC{schweitzer_wolf_1575846999, author = {Wolf Schweitzer}, title = {{Technical Below Elbow Amputee Issues - Artistic visions for prosthetic design III - playing with instructions and materials}}, month = {May},year = {2009}, url = {https://www.swisswuff.ch/tech/?p=176}}