A drill guide apparatus includes a body providing a workpiece clamping surface. The body includes one or more drill guides, wherein the one or more drill guides pass through the workpiece clamping surface at an acute angle, a first track, and a second track. The drill guide apparatus further comprises a first slider mounted on the first track, and a second slider mounted on the second track. The first slider includes a first extrusion that extends beyond the workpiece clamping surface and is slideable along the first track to adjust the position of the first extrusion relative to the workpiece clamping surface. The second slider includes a second extrusion that extends beyond the workpiece clamping surface and is slideable along the second track to adjust the position of the second extrusion relative to the workpiece clamping surface. The drill guide may also include a removeable clamp retainer.