Shop-Made Clamps Hold Tight and Save Money
To build the clamps, cut the jaws to the dimensions shown or choose a size suitable for your needs. Lay out the centerpoints for the dowel holes in the same position on the sliding and fixed jaws, but drill the rear dowel hole for the fixed jaw at a 2° angle as shown. Then, glue the dowels into the holes on the fixed jaw.
The secret to these clamps is in the 2° angle of the rear dowel and the 2° bevel on the clamp pad of the sliding jaw. The sliding jaw will move freely until you place a workpiece between the clamping pads and squeeze the jaws together.
Because the dowels are not parallel, the sliding jaw wedges against the dowels, much like an old-fashioned bench hold-down secures a workpiece when you tap it into a hole in a bench. And the 2° bevel on the clamp pad aligns parallel with the pad on the fixed jaw. To loosen the clamps, just tap the rear of the sliding jaw.
—Carl Rasmussen, Winnipeg, Manitoba