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Previous post in the sequence:

Walky the Biped Robot - The prequel

Walky the Biped Robot - Power pack


Walky has always had a prominent place around my workspace since it was created.

Unfortunately, yesterday afternoon Walky suffered a pretty major accident.  I was in the process of adding a couple of holes to assist in cable routing, when the drill stuck and 'crack', Walky was in pieces (I know that I should have been using my 'plastic' drill bits, but I was sure I could go slow enough to get a clean cut).  At first I thought, I will be able to re-glue him, but after a bit of reflection, I decided that maybe it is time for Walky II.  'Rest in Pieces Walky'.

I had been working on building a mounting board for attaching the new controller board (adapting the existing hole patter on Walky's top to the new board), when I noticed that the servo wires were going to making some tight bends.  So a couple of side holes seemed like a good idea.  This is where having a 3D printer is so cool.



Here is the new servo controller (blank) attached to the mounting bracket and mated to the power pack board (gently positioned around Walky's broken body.  You might noticed that the power pack is sans battery.  Another interesting story there.  I had attached a 'flying lead' to the positive terminal of the battery on the power pack to allow me to externally monitor the battery voltage during charge/discharge testing.  While I was designing the mounting bracket for the servo controller board, I was using the power pack to capture some dimensional measurements.  At one point in the process I began to smell smoldering plastic.  At first I thought it was the 3D printer.  No, not there.  I kept looking around until I noticed that power pack under my note pad.  Digging it out I noticed the outer sheath of the battery was split and discolored.  Not to mention that the battery was smoking hot!  I found the 'flying lead' welded to the metal housing of the USB connector (ground) and quickly removed it.  I then quickly took the power pack out to the garage where I was able to extract the battery from the power pack (with pliers). Don't do this at home folks.  I later had to explain the burnt smells coming from the office to my wife (who was currently doing a little burning of her own, while roasting some vegetables.  I guess that family that burns together stays together.






Now it was time to start on the body of Walky II.  I ended up with a split case design for the body.


It is kind of cool that I can simply mirror the design of this side to create the other side.  I added some through hole mounting holes inside of bosses to join the two halves.  In retrospect it would have been nice to add some alignment pins/holes to the edges to help keep the case halves together.  I am currently printing the first half, so time will tell as to the correctness of this design. (We have been having some thunderstorms lately and lost power a couple of times.  Since my 3D printer is not on the UPS, I will have to hope that I can couple the 4 hour prints without power interruptions)


I still have not decided if I will continue to re-design Walky, i.e. new legs and feet.  I guess that it will look a little better (more color coordinated) if I do.


Thanks for reading along.  More to come.