I designed and analyzed a compound-reverted gear train with 45° helical gears that can transmit 0.4 HP at 1800 rpm in either direction, with a 15:1 gear ratio. Components, such as gears and bearings, were selected from catalogs to meet industry standards. The use of helical gears introduced challenges, such as accounting for axial loads and the effects of the helix angle on gear geometry and force transmission. Additionally, I wrote MATLAB code that plotted shear, moment, slope, and deflection along each shaft profile to identify critical locations. This was the first project I worked on that tested my understanding of GD&T standards, and initially, my part drawings for the shafts lacked a clear datum structure, making it difficult to control runout and gear alignment. To ensure that these features were met, I revisited the ASME Y14.5 principles, corrected the over-constrained tolerances, and redefined the datums. This entire learning process highlighted how neglected proper GD&T application leads to such headaches on the manufacturing side of engineering.