Stop in for a cup of coffee

We use them in oil field for welding and fitting tanks. Of course we use a bit heavier material than posted pix. But basically you put clamp on the low side with screw positioned over high side. You tack inside of the foot and as you screw down tack acts as fulcrum and pushes against foot for leverage when two plates line up you weld it. Unscrew threaded portion pop the clamp with a hammer and bust it off. Move down the seam and rinse and repeat.