Thermal Deformation to Warm Up our Winternship

Happy Holidays!

Welcome back to the chronicles of Jag and Elda, who are learning how to produce prosthetic hands under the training of Kassem AlHussein. While the holidays were great, it's time to get back to work.

Our goal for these two weeks is to create two fully mechanical-working prosthesis. Our game plan to achieve this goes through a couple of steps:

     
      -Learn thermal deformation to shape the upper part of the prosthesis
      -Refine the arm by using acetone on ABS filament.
      -Print normally sized prosthetic hands at a scale of 130% , i.e. print in part
      -Assemble the hands with all necessary hardware (fixed and flexible strings, etc)
      -Deal with printer troubles along the way, while we wait for our Atom 2.5 printer to come in.
      -Learn CAD (Solidworks, Fusion) to edit, manipulate and design prosthetics

Thermal Deformation

While PLA melts at 205-220 degrees, at around 80-90 degrees it's just soft enough to manipulate. While people come in different shapes and sizes, we will need arm models in different shapes and sizes. One way we can make our arm model reshape according to the person it is for is to put the PLA filament in hot water.
We started the evening by printing out two long rods. During the printing, Kass explains the process of thermal deformation: the act of reshaping material because of its ability to disfigure in heat.
Soon we noticed that the nozzle of the Ultimaker was not extruding, so we thought that it was clogged. Sure enough, some material was clogged up and we unclogged it by pushing a thing rod through it. Even after that, though, it would not print. We clicked Material >> Change filament, and noticed that the gears in the motor were stuck on the part of the filament seen below - the reason why there was no extrusion.
To recap: small prints should have 100% infill if we want them to be sturdy, while for larger objects it can be a smaller percentage. Normal prints usually go up to 30% though. 
Back to the thermal deformation. We put the material into the hot water for a couple of seconds. The thicker the object, the more we keep it in the water. Theoretically, 80-90 deg works to mould our plastic. However, we found that boiling water works for OUR PLA material. 

Things to buy: Glue, strings, cubicle decorations, material for next week's training sessions.