It has taken the better part of two weeks, but I have finally devised a satisfactory method for affixing the stair balusters to the stair treads at the River House. I purchased 150 round 5/8″ diameter hollow metal tubes to fashion the balusters. When they arrived, I discovered they were neither 5/8″ in diameter nor truly round both of which I was counting on to mount them using my original concept. Since then, I have experimented with several different approaches but none provided the lateral stiffness I am looking for. Today, I finally arrived at a robust and cost-effective solution. I predrill and drive a 1/2″ lag screw into the stair tread using a jig to make sure it is normal to the plane of the tread. Next, I cut off the hex head of the screw. Then, I fashion a short piece of 14 gauge wire into the shape shown in the photo and place it over the screw shaft. Finally, I drive the hollow tube over the assembly. This creates an interference fit along three lines (one on each wire and the third on the opposite side of the screw shaft). When I tested the connection it was as if I had set the baluster in concrete.