C-3PO arm - large printer

thingiverse

This is an arm model created primarily through picture analysis but also incorporating elements from Starbuck Cylon parts and Gordon Tarpley's YouTube tutorials. The forearm is a single piece, while the bicep consists of two separate components to provide a flat surface for assembly. These two pieces are designed to fit together for precise alignment. The arm model is intended for large format printers such as the CR-10, although I've also created another version that might be more suitable for smaller printers. I used 35% infill but acknowledge that it doesn't significantly impact the print quality, given that most of the shaft remains solid. The forearm and bicep cuff are identical on both arms, with the exception of the bicep body which is handed; users will need to reflect it when printing the left arm. A bar located at the bottom of the bicep body serves as a rotational locator for the cuff once the parts are glued together, allowing for easy trimming and sanding to achieve a flush interior surface. Additionally, this feature provides extra adhesion area to secure the part to the printer bed. Update on February 16, 2018: I modified the holes at the elbow from traditional holes to dimples. This change was made in response to issues encountered during printing, where retraction caused weakness at the inside of the elbow when transitioning between sides of a hole. Dimples allow for continuous bead formation throughout each layer and provide a positive feature for drilling clean holes. A small nub was also added on the outside of the elbow for precise location of the piston anchor. Uploading other greeblies and assembly components shortly. Long overdue update: I promised to share details about the piece intended for the piston connector. Below, you'll find a snapshot of the model along with a PDF drawing. The piece is crafted from extruded aluminum, measuring 1"x1" in size and 1/16" thick. To create this component, I printed out the drawing in actual size, cut it to profile using scissors, and then shaped it with a hacksaw and files until it matched the paper template. Once assembled, I secured the piece in place using epoxy.