Shoulder Double Joint

thingiverse

A double-revolute joint functions effectively as a shoulder joint. It comprises three distinct components: Alpha, Beta, and Charlie. The 'Alpha' component is designed to fit snugly over a piece of wood measuring 29mm in width and 17mm in height, with a socket depth of approximately 15mm. In contrast, the 'Charlie' component is intended to slot over 20x20 aluminum extrusion. With access to CAD software like Fusion 360, users can modify the .STL files for both components to accommodate any desired specifications. The 3DP nut and bolt used in this joint have been adapted from https://www.thingiverse.com/thing:193647 by mike_mattala, but they are relatively weak, particularly when printed with PLA. It is essential not to overtighten the top, as it may snap off the bolt. For optimal results, print the main parts of the joint at 25-30% infill and 0.15mm resolution, then use finer 0.1mm resolution and 50% or higher infill for the nut and bolt to achieve a well-defined thread and maximize the bolt's strength. Ultimately, I plan to replace the 3DP bolts with steel ones in my own model.