Despite our best efforts, all of our projects don’t get completed. Even when they’re taking a long time or have trailed off, the parts that are finished can still be helpful and that’s the case with Instructables user thejuggler’s Arduino-powered tentacles project. He designed the appendages for a Slenderman costume and went through several versions of the tentacle to get the final design just right. The above photo shows version 1.0 that was made from PVC and MDF discs:
After I had the right size discs, I cut short lengths of PVC to be connected to them, and hot glued the two together. (Hot glue, like duct tape, is a fantastic tool for quick, dirty fixes, but not for robotics. In the final version, I knew I would have to find something a little more precise.)
Next, I had to figure out how to make the PVC vertebrae slide smoothly against each other. I was unable to find any good system for PVC hinges, so I decided to make a ball joint. I made a sphere of approximately the right size in Solidworks, and then 3D printed them into existence. If I were to do this part over, I would have added a hole down the center of each ball before printing them. As it was, I used a drill press and some scrap wood as a jig to drill a hole in each.
I then connected everything down the middle using tent shock cord to keep the tension, and tied/hot glued it off at each end. After running some spare twine down the sides as the control cables, the first draft was complete.
This first “tail” was far from perfect; it was heavy, and didn’t move as it was supposed to.The problem I discovered was that it twisted on itself too much instead of moving directly in the direction it was pulled. This first prototype has been very educational, but it was time to move on to version 2.
He was pleased with third version of the tail (you can read about all of them at Instructables) and moved onto testing adding skin to the tentacle skeleton and figuring out the robotics. He planned to use an Arduino Uno to be the brain and to control movements with a Wii Nunchuk in each hand.
Read more about the progress of the build at Instructables.