Difference in Profile Method

When we develop a pattern from elevation view, we have no way to see how far the fitting is leaning front to back. Because of the 2D view, we don’t see the depth of the shape. Since we know the general shape of the fitting, we can assume that there is movement in the element lines. But we need to know how much to find the True Length (TL) of the line. We accomplish this by comparing the profile lines found at each end of an element line, this is called “Difference in Profile”. As you will see in the following fittings, if we take the profile line from each end of any element line and compare them, the difference is how far the fitting is leaning, front to back, at that point. It doesn’t tell us which way, but that doesn’t matter. Only that it is moving is necessary to know. For this process to work though, we must have the top and bottom on a line of symmetry and be centered front to back. Any offset can only be shown left to right in the elevation view. This is the case for all fittings we will develop by this method.