This is a project that I have been working on for 3 years now which is a fully 3D printed and functional Robotic torso I have dubbed PROTO1.
I've published other prototype robotic arms and prosthetics I've designed mainly as a hobby including my "Humanoid Robotic Hand" which was just the arm of Proto1. The publishing of the complete set of files for the robot has been long overdue, but it is finally here. The chest is almost finished as well but I am still working on the designs for it, but I mostly need funding as of now so anything helps. The total cost of this robot between material, electronics, and everything else used is around $300 which can be a bit more or even less depending on where and what kind of materials you get.
The arm features a 3-axis shoulder to obtain full human motion. The elbow uses a large servo connected to it by a grooved belt (the same kind of belt used on most FDM 3D printers), the belt allows the full 180 degree range of the servo to be channeled into the ≈100 degrees that the elbow moves. This is visualized much better in the video provided. The Hand itself is composed of 6 servos. Between those 6 servos, it's able to obtain 180degree wrist motion, an opposable thumb, and individual finger motion for all fingers except the ring and pinky which move as one unit (So you can't do the rock sign with it :'( but you can give the peace sign or flip the bird if it is ever necessary). It is also worth mentioning that the largest piece is 91mmx91mmx127mm so if your printer can print those dimensions it will be able to print every piece.
The full Parts List for a single arm is:
Micro Servo x1
Standard Sized servo x5
60kg.cm Servo x2
Minimum of 100kg.cm torque servo x2, this servo needs to be this type of design to fit in the shoulder piece properly
Servo wire extensionsMethod of control (I use a number of different programs to control the arm such as the arduino and pololu servo board)
My partner Thomas Anderson deals with most of the code for the robot and all his code for the arm can be found at his gifthub page here
I hope you guys like my design, if you have any comments or questions you can leave it down below or email me directly at firstname.lastname@example.org