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-describe CAD work
-link length sized to desired horizontal rail length
-designing gripper head to be controlled by 1 servo
The first mechanism is based off of a scissor lift, and allows the grabbing head to articulate forward. It's comprised of 8 links which are 3D printed out of ABS plastic. 3D printing the links instead of laser cutting them out of acrylic, allows us to tune the fit of the bearings, allowing a precise press fit. The ABS plastic is also relatively light weight and stiff. Each link has 3 inexpensive RC car bearings, which provide for low friction actuation. In order to prevent the links from rubbing together, they are separated by a 1mm thick ABS spacer. The links are joined together with 5mm stainless steel pins, which were manufactured in the machine shop.
The scissor mechanism is supported by a 3D printed base. The base straps to the users arm and allows the scissor mechanism to open and close via a rail and slider. The scissor mechanism has a special drive link that allows the mechanism to be joined to a high torque RC servo. When the drive link is rotated the mechanism opens and closes.
