The Squaring Platform presents a flat surface parallel to the horizontal plane of a grand action. Raise the height of the platform so that its sliding top will extend over the backchecks with the keys at rest. Then, fine-tune each corner to the same height using the Depth/Angel Gauge. Sliding top contracted, use a Shank Traveler from its surface to travel shanks vertically. Then, sliding top extended, support shanks on the support rail to square hammers at strike with a Hammer Square.