Stir welding usually lives behind factory doors, with heavy rigid machines and purpose-built rigs doing the work. Here AvE is on a second attempt at doing it at home, using shop-made tooling held in the spindle of a vertical milling machine and working a thick slab of aluminum. Compared with the usual way of running this process, that is a refreshingly modest setup for something that normally demands serious rigidity and force.
The build itself is pleasingly hands-on. A custom-machined pin gets held in a lathe chuck, and the maker sharpens and polishes the pin profile while the chuck turns, using a handheld power drill for the job. The finished tool then goes into the mill spindle. For the first test, two aluminum strips get clamped flat on the table, and the spinning pin works the seam between them, generating frictional heat. That initial butt-joint clamping fails. Afterward the maker moves to a stacked lap joint held down with four toe clamps, runs the pin through the upper sheet, and stirs aluminum that behaves like a molten mush. A second lap pass follows once the pulley ratio has been changed.
What stands out to me is the weld track, which shows concentric circular swirl patterns inside it, a satisfying sign of genuine stirring, and the stacked sheets do end up joined, with plenty of aluminum squeezed out along the way.
The trade-off sits in the results: the plates come out heavily distorted, pushed upwards, and covered in flash. Pin shoulder geometry, belt pulley speeds, and aluminum building up on the tool all clearly needed attention, and whether a cleaner pass is reachable on this kind of machine still looks like an open question.
Project by AvE. Watch it on their YouTube channel: