MIG welding isn’t very difficult — at least not until you need to weld something at a weird angle or over a long seam. Those situations will make your welds look like they were done by an inebriated amateur. The best way to handle that is by setting yourself up to maintain stability through the entire weld. For achieving that on round objects, Greenhill Forge constructed a Arduino-controlled custom rotary welding table.

Tables like this have one job: to rotate the workpiece in front of your welding gun, so you can stay in a stable position while it moves. That’s a simple job, but there are a few important “gotchas” that Greenhill Forge cleverly took into account.

Structurally, this is just a mild steel frame with a heavy-duty lazy Susan bearing and a circular mild steel top. That’s the kind of thing even a beginner welder could throw together in an afternoon, assuming you have a way to cut the steel (that circular top might be challenging).

Those “gotchas” relate to the welding process. You want the top to spin at a consistent speed and you want that speed to be adjustable. You also want a good path for current to flow from the ground clamp to the wire.

Greenhill Forge handled the rotation with an Arduino UNO Rev3, a stepper motor with a gear reducer, and a spider coupler mating to a shaft welded to the underside of the tabletop. A rotary encoder lets the user set the rotation speed and a small OLED screen lets them see the speed value (for setting the same speed again later).

For the ground path, Greenhill Forge wrapped a ground strap around the shaft above the spider coupler. So, the current path is ground clamp, to ground strap, to motor shaft, to table, to workpiece, to wire. It lets the top spin freely without tangled cables, and avoids any danger of current going to the electronics.