How do you drill 4 holes in precisely the same location on each of 29 stair treads? You build a jig. Pictured below is a close-up of the jig I fashioned to aid in this task. The stainless steel sleeves act as guides for the 1/2″ drill bit ensuring that the hole is perpendicular to the face of the stair tread and located in exactly the right position. Not shown is the other end of the jig which has two additional guides and a lip to register the entire assembly to the stair tread. Clamps secure the jig to the workpiece during drilling. Fabricating the jig took longer than drilling all 116 holes but it was meant to ensure precision rather than to optimize speed.