row_2 = row_1 + v_margin + 12; row_1 = bottom_row + v_margin + 12; row_2 = row_1 + v_margin + 12; row_1 = v_margin+12; Initial stab at a charge no more than 100k to get proper hole sizes threeUHeight = 133.35; //overall 3u height panelInnerHeight = 110; //rail clearance = ~11.675mm, top and bottom boards. Final work on PCB with.