Prosthesis: The Anti Robot

We’ve been plugging way at putting the base together and it is finally taking shape. At this point, the scale of this project begins to sink in. We need to use the crane to flip the huge structure so we can start TIG welding in the finer structure underneath to give it strength and stiffness. Time to teach the team to TIG weld.

With the base well under way and the UBC Engineering Suspension and Hydraulics teams blazing ahead with their designs the pressure is on to have a leg design ready for fabrication. Finding the balance between an elegant and sexy leg, and something that can be built in time by the ever more skillful team becomes critical. This image shows a well well evolved Upper Leg and a very simplified Lower link (the square tubes). Square tubes are not sexy, but they’re easy to fabricate with.

The design is progressing nicely. There is so much engineering and design that goes into producing fabrication ready parts, but it’s not until all the prep work is done that you can finally generate drawings and start cutting metal. It’s like painting a room. Clean the walls, cover the funiature, fill the holes and then, in one busy weekend, the room suddenly changes colour. This CAD rendering represents only what’s ready for painting.

This is my usual position during our intensive build sessions in the eatART Lab. I have a team of dedicated and hungry fabricators that I need to feed parts to. The tight timeline we’re gunning for in order to get the prototype leg built in time for the hard working UBC students means that design and fabrication must take place in parallel. This is a deviation from the ideal of having everything fully designed before the build begins, but with enough focus, and the proper systems in place, parts can be fed out Just-In-Time. Crank.

As the team all learn the basics of wire feed welding the pace picks up.
Left:An attentive group watches how it’s done. Right: Polly takes the torch and lays some beads.

On John’s advice (insistence) we used flux-core wire feed to weld the sizeble members that make up the base of Prosthesis. Dylan is breaking in his “Project Hoodie”. It’s cleanliness will be used as a metric for his shop time as the project progresses.
The flux in flux-core, as John explains, consumes the oxygen and other impurities on the metal’s surface as it vaporizes, allowing lots of metal joining heat to be poured in to the weld and minimal cleaning of the salvaged metal.

Veteran ship builder John Blake lends his decades of experience building large things to the team. With the extent of my intuition topping out at 1″ tubing, this sort of knowledge is just what we need to make sure the huge 4″ x 4″ x 1/4″ tubing for the base goes together properly. Mark and Dylan soak it in.

As a way to entice volunteers to help me build Prosthesis, I have offered to teach a select group of friends who have expressed interest in helping build Prosthesis over the years, what I know about welding and fabrication. I learned most of what I know from my experience building the Mondo Spider. I’ve taken a six week course at BCIT (a local trade school) but once you know the fundamentals, the only thing that can really teach you to TIG weld is practice.

The original plan was to train everyone on the CNC tubing cutter and have them build a project of their own design, like a bike rack, or a coffee table, but with Project Alpha on the critical path, it’s in to the deep end and sink or swim. Luckily, I’m not the only one with some experience on the team. Veteran ship builder, John Blake will be lending his decades of experience and my right-hand man on the Spider legs, Ryan Johnston will be helping people get the feel for the torch. Mark Eijsermans also has foothold on metal fab from his work on the Gramorail and Tim Lukian has been producing some fine brazed CrMo bike racks of late. Polly Tan and Brad Sieber have carpenters hands and the rest of the team all bring focus and dedication to the table. I have a feeling I have a ringer team on hand.