A fixture for setting rebar at a predetermined distance from the rim of an excavated pit includes elongated first and second legs each having a proximal end and a distal end, the first and second legs rigidly joined at their mutual proximal ends to form an L-shape; an angle adjustment device carried by the first leg, comprising a foot movable towards or away from the first leg along an axis generally parallel to the second leg; a support bracket carried by the first leg at a predetermined offset distance from the proximal end thereof; and a hook extending from the distal end of the second leg, generally parallel to the first leg.