Square tube expansion plug

thingiverse

Your Baby-Huey 3D printer project features a unique fixing system inspired by rawlplugs, designed to fit into the end of square tubes. This filleted square plug has a tapered hexagonal hole that secures a nut. The design file is parametric, allowing easy modifications of nut size, tube size, and taper simply through parameter adjustments. As your first freeCAD project, it may not be the most refined design; however, it serves as a solid starting point. This expansion plug, found in the expansion-plug-a.stl file, is specifically tailored for 25mm square tubes with 3mm walls, featuring a nut measuring 13.5mm face to face and a 5-degree taper. Although not intended for extremely heavy-duty applications, it should suffice for constructing a 3D printer frame. The plug was initially designed for ABS material; however, your test print in PLA proved successful with minimal adjustments using a file to widen the round hole. While the hexagonal hole may feel tight, drilling it out slightly should resolve this issue. Currently, the expansion plug remains untested under serious loads, but initial results appear promising for its intended purpose within your Baby-Huey 3D printer project.