This designed gap has functional requirements (being part of a greater assembly) and, for proper operation, the gap size must be such-and-such-a-value with an allowable variation of such-and-such-a-value. The intent is that they will 'stack up' against the side of the cavity, thus leaving a designed gap on the other side. Those blocks were designed to fit side-by-side in contact with each other and within the cavity of the larger part. In that cavity will sit three blocks of the same width (at least they are designed that way). There is one part with a squared-off, U-shaped cavity in the middle. (I would like acknowledge James Ministrelli, DFSS Master Black Belt and GD&T Guru Extraordinaire, for his help & advice in these posts. The explanation begins with probably the most overworked example found in dusty tomes (my apologies in advance). An engineering-centric term in the Tolerance Analysis world would be Tolerance Stacks, usually meaning in a one-dimensional sense. Let us describe the simplest of the three, the Worst Case Analysis (WCA) approach. As stated in my last post, there are three common approaches to performing Tolerance Analysis.
