The whole project started with a simple problem: two old twelve inch C-clamps had lost their original feet, and the store-bought replacements did not work as-is. Those commercial pads sat too deeply over the ball ends of the screws, and a conical drill-point bottom inside each pad kept the pad from pivoting properly on the ball. Rather than give up on the pads, the maker decided to rework them.
The rework is where this gets interesting. A touch probe centered each pad held in a chuck, and then an end mill cut a flat bottom into the pad cavity, doing away with that cone-shaped floor. On the lathe, round steel stock was turned to diameter to make spacer inserts, and a concave hemispherical socket was machined into each one to seat the ball end. Each finished spacer was parted off with an arbor-mounted slitting saw, with spray lubricant applied during the cut.
Assembly looks satisfying too. The spacer was pressed into the pad using the clamp against a wooden block, and an internal wire retaining ring sits in a groove in the pad to hold everything captive. Snapped onto the clamp screw, the finished assembly showed full swivel action.
One trade-off worth noting: this fix turns a simple pad swap into a multi-part assembly, with a turned spacer and a retaining ring per pad. That seems a fair price for clamps this old getting their feet back.
Project by MakersEase. Watch it on their YouTube channel: